<div dir="ltr">This RFC describes the data structures to hold the ThinLTO function index/summary used to support function importing. It also describes the high-level APIs for reading and writing this information. As discussed in the high-level ThinLTO RFC <span style="font-size:12.8000001907349px">(</span><a href="http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-May/086211.html" target="_blank" style="font-size:12.8000001907349px">http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-May/086211.html</a><span style="font-size:12.8000001907349px">), we would like to add support for native object wrapped bitcode and ThinLTO information. Based on comments on the mailing list, I am adding support for ThinLTO in both normal bitcode files, as well as native-object wrapped bitcode.</span><div><br></div><div>I've implemented support for the data structures in <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__reviews.llvm.org_D11721&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=Mfk2qtn1LTDThVkh6-oGglNfMADXfJdty4_bhmuhMHA&m=U1ae_Mbki7aQS7EnGnTJvjTiKNxCarCAQznk00v2bmQ&s=QuNJAvRaY1Vtkaj-FX5vJdw9WcDPMu56V3vHsjySWA0&e=" rel="noreferrer" target="_blank" style="font-size:12.8000001907349px">http://reviews.llvm.org/D11721</a>, and support for some of the APIs (not the libLTO API's, but the underlying ThinLTOObjectFile interfaces used by both libLTO and directly by gold) in <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__reviews.llvm.org_D11723&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=Mfk2qtn1LTDThVkh6-oGglNfMADXfJdty4_bhmuhMHA&m=U1ae_Mbki7aQS7EnGnTJvjTiKNxCarCAQznk00v2bmQ&s=rl4CPjxWwTmZbfJjKGk68Tjsm8YB1PUw6k0q9p5Fqpk&e=" rel="noreferrer" target="_blank" style="font-size:12.8000001907349px">http://reviews.llvm.org/D11723</a>.</div><div><br></div><div>The file format is described in a separate RFC I am sending simultaneously, which contains a pointer to the patch implementing the bitcode reading/writing support.</div><div><br></div><div>Looking forward to your feedback. Thanks!</div><div>Teresa</div><div><br></div><div><ul class="ul1">
</ul></div><div><span id="docs-internal-guid-ab3546cd-f44f-efe8-2359-9e5f52108b1d"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:28px;font-family:'Trebuchet MS';color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">RFC: ThinLTO File API and Data Structures</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal" id="docs-internal-guid-ab3546cd-f457-20df-494c-4b3538e2f0b3"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This RFC covers a proposed API for ThinLTO clients (e.g. gold plugin, linkers, llvm-lto) to use when reading and writing ThinLTO information from bitcode files (raw or wrapped). The APIs are meant to hide the underlying format of the files, much as the existing LTOModule and IRObject interfaces hide the format when reading bitcode (i.e. they work transparently on native wrapped bitcode).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">See the following thread for background on ThinLTO and motivation for the APIs:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><a href="http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-June/086310.html">http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-June/086310.html</a></span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><h1 dir="ltr" style="line-height:1.38;margin-top:10pt;margin-bottom:0pt"><span style="font-size:21.333333333333332px;font-family:'Trebuchet MS';color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Current Interfaces</span></h1><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Currently linkers such as ld64, lld and some proprietary linkers (e.g. Sony), as well as the llvm-lto tool, utilize libLTO to read bitcode intermediate files. Specifically, they use the LTOModule class and interfaces, or the C interface to these (lto_module_* routines). The gold plugin performs many of the same steps, but interfaces directly with the underlying IRObjectFile class, encapsulating the following in the IRObjectFile::create static method.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Check if file/mem contains bitcode (including native object wrapped bitcode)</span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static bool LTOModule::isBitcode* and lto_module_is_object* interfaces</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Reads file into a MemoryBuffer and invokes static IRObjectFile::findBitcodeInMemBuffer which:</span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:square;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">If memory buffer is bitcode, return as is</span></p></li><li dir="ltr" style="list-style-type:square;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">If memory buffer is object file, invoke ObjectFile::createObjectFile, then IRObjectFile::findBitcodeInObject to look for .llvmbc section, if found return memory buffer for section contents</span></p></li></ul><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Return true if findBitcodeInMemBuffer returns non-null</span></p></li></ul><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Read and parse bitcode from file/mem, build Module, returning LTOModule/lto_module_t object</span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static LTOModule * LTOModule::createFrom* and lto_module_create_from* interfaces</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Same steps as the isBitcode interface above, but if findBitcodeInMemBuffer returns a memory buffer:</span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:square;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Parse into a new Module object (or get a lazy bitcode parser Module) via BitcodeReader interfaces.</span></p></li><li dir="ltr" style="list-style-type:square;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Create IRObjectFile object (derived from SymbolicFile), save Module here</span></p></li><li dir="ltr" style="list-style-type:square;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Create LTOModule object, save IRObjectFile here</span></p></li></ul><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Return LTOModule object</span></p></li></ul></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The classes referred to above look like (only the relevant members shown):</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">include/llvm/LTO/LTOModule.h:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">struct LTOModule {</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">     ...</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">     std::unique_ptr<object::IRObjectFile> IRFile;</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">     …</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">include/llvm/Object/IRObjectFile.h:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">class IRObjectFile : public SymbolicFile {</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">  std::unique_ptr<Module> M;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">  ...</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">include/llvm/Object/ObjectFile.h:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">/// ObjectFile - This class is the base class for all object file types.</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">/// Concrete instances of this object are created by createObjectFile, which</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">/// figures out which type to create.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">class ObjectFile : public SymbolicFile {</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">  ...</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">include/llvm/IR/Module.h:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">class Module {</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">  …</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><h1 dir="ltr" style="line-height:1.38;margin-top:10pt;margin-bottom:0pt"><span style="font-size:21.333333333333332px;font-family:'Trebuchet MS';color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">New Interfaces for ThinLTO</span></h1><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><h2 dir="ltr" style="line-height:1.38;margin-top:10pt;margin-bottom:0pt"><span style="font-size:17.333333333333332px;font-family:'Trebuchet MS';color:#000000;background-color:transparent;font-weight:bold;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">High-level API Descriptions</span></h2><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The following main interfaces (e.g. in libLTO) will be needed to support ThinLTO (detailed interface descriptions and data structures can be found further down):</span></p><ol style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Write per-module index/summary to intermediate file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface writes the ThinLTO function index/summary for a module to the intermediate file containing its bitcode (either bitcode only or native object wrapped), and is invoked by the compiler during intermediate object emission.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre"> </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output stream to write it into</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="2"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Write combined index/summary file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface writes the combined function index/summary to a file. This is the combined index/summary created by the plugin step from all modules. The output file format will depend on the format of the intermediate files (bitcode only or native object wrapped).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">   </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output file path</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"><br class="kix-line-break"></span></p></li></ul><ol style="margin-top:0pt;margin-bottom:0pt" start="3"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">ThinLTO intermediate file identification</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface checks if an file or memory buffer contains a ThinLTO function index/summary. File (possibly in memory buffer) can contain either bitcode only or native object wrapped bitcode.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">        </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Input:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">File or memory buffer to check</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">  </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Boolean</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="4"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Read per-module index/summary from intermediate file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface will read and parse the ThinLTO function index/summary from an intermediate file for a module (either bitcode only or native object wrapped).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">        </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">File or memory buffer to check</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre"> </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary for module (format discussed below)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="5"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Read entire combined index/summary file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface will read and parse the combined function index/summary file. The file format will depend on the format of the intermediate files (bitcode only or native object wrapped).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">     </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Combined index/summary file path</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">       </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary object (format discussed below)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="6"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Read given function from combined index/summary file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface will read and parse the combined function index/summary file, parsing and populating the summary information for a single given function. The file format will depend on the format of the intermediate files (bitcode only or native object wrapped).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">        </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Combined index/summary file path</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Function name</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">   </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary object (format discussed below)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Some design considerations for the new interfaces:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interfaces 1, 5 and 6 are used internally by the compiler.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interfaces 2, 3 and 4 are used by the linker, and therefore are callable via libLTO and from the gold-plugin.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Just as the bitcode file format is transparently handled by the existing interfaces described above, the new ThinLTO interfaces should be similarly independent of the underlying format (bitcode only vs native object wrapped). </span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interfaces 5 and 6 are similar, and may not both be needed eventually, depending on tradeoffs investigated when tuning the ThinLTO implementation.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The interfaces for reading and writing the function index/summary should look very similar regardless of whether we are doing the per-module versions (1, 4) or the combined index/summary file (2, 5, 6). This is both for consistency and to allow the implementation to share as much code as possible. This design goal also means the format of the index/summary in the module and in the combined file should be similar.</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><h2 dir="ltr" style="line-height:1.38;margin-top:10pt;margin-bottom:0pt"><span style="font-size:17.333333333333332px;font-family:'Trebuchet MS';color:#000000;background-color:transparent;font-weight:bold;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO Function Index/Summary Data Structures</span></h2><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">In order to save time and memory in the plugin step, we don’t want to parse the entire bitcode for a module during the plugin step (which only needs to read the function index/summary for merging into a combined index/summary). We also don’t need to parse the ThinLTO information out of the module’s IR when constructing the Module object during the backend compile step (the ThinLTO importing step will read the combined index file, not the module’s own ThinLTO index).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Therefore any data structure created to encapsulate ThinLTO function index and summary information should be independent of LTOModule and IRObjectFile, as those structures are created when we read/parse the module’s normal (non-ThinLTO) bitcode, and result in the creation of a Module object. This also simplifies the implementation of reading/writing interfaces that can be shared between bitcode only and native object wrapped bitcode formats, since the latter will represent the ThinLTO information in a separate section and in the object’s symbol table.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">For a description of the bitcode and native-wrapped file formats, see the separate “ThinLTO File Format” RFC.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The proposed new data structures are outlined below. As mentioned earlier in the interface design considerations, they are totally independent of where the function index/summary sits in the intermediate file (whether in a bitcode block or a native wrapped section/symtab):</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTOModulePathStringTable: String table to hold/own module path strings, which additionally holds the module ID assigned to each module during the plugin step. This can simply be a typedef StringMap<uint64_t>, since the StringMap makes a copy of and owns inserted strings. </span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTOFunctionInfo: Class to hold function’s bitcode index and summary info. Includes:</span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Module path StringRefs (module strings owned by ThinLTOModulePathStringTable)</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Bitcode index of function in the module</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTOFunctionSummary: Function summary information to aid in importing decisions (e.g. instruction count, profile count).</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Transient information used while reading/writing function summary from file (specifically the function’s offset into encoded function summary section) </span></p></li></ul><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTOFunctionMap: Mapping from function name to corresponding ThinLTOFunctionInfo(s)</span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Implemented via StringMap class, which makes a copy of and owns inserted (function name) strings.</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">There may be more than one ThinLTOFunctionInfo for a given function name in the combined function index/summary map due to COMDATs. While the plugin step that creates the combined function map may decide to select one representative COMDAT instance, we don’t want the design to preclude holding multiple as it may be advantageous to import a particular COMDAT from different modules in different backend instances.</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Therefore, use StringMap< std::vector<ThinLTOFunctionInfo> ></span></p></li></ul><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTOFunctionSummaryIndex: Class to hold ThinLTOModulePathStringTable and ThinLTOFunctionMap and encapsulate methods for operating on them</span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Includes method for combining from another given ThinLTOFunctionSummaryIndex instance (used when creating combined index/summary map.</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Used to hold both per-module and combined function index/summary.</span></p></li></ul><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Class ThinLTOObjectFile </span></p></li><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Analogous to IRObjectFile, but holds ThinLTOFunctionSummaryIndex instead of Module</span></p></li><li dir="ltr" style="list-style-type:circle;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Derived from SymbolicFile</span></p></li></ul><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">New libLTO class ThinLTO</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The new classes referred to above will look like (only the relevant members shown):</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">include/llvm/LTO/LTOThinLTO.h:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">struct ThinLTO {</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">     ...</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">     std::unique_ptr<object::ThinLTOObjectFile> ThinLTOFile;</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">     …</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"><br class="kix-line-break"></span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">include/llvm/Object/ThinLTOObjectFile.h:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">class ThinLTOObjectFile : public SymbolicFile {</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">  std::unique_ptr<ThinLTOFunctionSummaryIndex> Index;</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">  ...</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">include/llvm/IR/ThinLTOInfo.h:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">    </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">typedef std::vector<ThinLTOFunctionInfo> ThinLTOFunctionInfoList;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">      </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">typedef StringMap<ThinLTOFunctionInfoList> ThinLTOFunctionMap;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">typedef StringMap<uint64_t> ThinLTOModulePathStringTable;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">class ThinLTOFunctionSummaryIndex {</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   ThinLTOFunctionMap FunctionMap;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   ThinLTOModulePathStringTable ModulePathStringTable;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">    ...</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">class ThinLTOFunctionInfo {</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   StringRef ModulePath;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   uint64_t BitcodeIndex;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   ThinLTOFunctionSummary *FunctionSummary;</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   uint64_t FunctionSummarySecOffset; // Used during parsing</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   uint64_t FunctionSummarySecSize; // Used during parsing</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   ...</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">class ThinLTOFunctionSummary {</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">   // TBD (includes function size, hotness, …)</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">};</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br><br></b></p><h2 dir="ltr" style="line-height:1.38;margin-top:10pt;margin-bottom:0pt"><span style="font-size:17.333333333333332px;font-family:'Trebuchet MS';color:#000000;background-color:transparent;font-weight:bold;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Detailed API Descriptions</span></h2><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">With the above data structures in mind, this section shows the refined and more detailed interface specifications.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Note that the bitcode reader interfaces are not shown here, since this document focuses on the higher-level API and data structures. But this will use a new ThinLTOBitcodeReader class which will save and populate the newly created ThinLTOFunctionSummaryIndex object (similar to how the BitcodeReader class saves and populates a Module object). The ThinLTOBitcodeReader class contains methods for parsing the ThinLTO bitcode blocks in a bitcode-only file, as well as the bitcode-encoded ThinLTO summary and module string table sections in the native-wrapped case. This is also discussed in the separate “ThinLTO File Format” RFC.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">API Details:</span></p><ol style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Write per-module index/summary to intermediate file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface writes the ThinLTO function index/summary for a module to the intermediate file containing its bitcode (either bitcode only or native object wrapped), and is invoked by the compiler during intermediate object emission (so no libLTO interfaces).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">       </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary object</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output stream to write it into</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">       </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Interfaces:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static void WriteThinLTOBlock(const ThinLTOFunctionSummaryIndex *Index, BitstreamWriter &Stream)</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">void llvm::WriteThinLTOToStreamer(const ThinLTOFunctionSummaryIndex *Index, MCStreamer &MCS)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">   </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Notes:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The former (taking a BitstreamWriter) is used when we are writing bitcode-only (invoked from WriteModule under the appropriate option) and the latter (taking MCStreamer) indicates we are writing wrapped to the given native object streamer.</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="2"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Write combined index/summary file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface writes the combined function index/summary to a file. This is the combined index/summary created by the plugin step from all modules. The output file format will depend on the format of the intermediate files (bitcode only or native object wrapped).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">        </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output file path</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output triple</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">      </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Outputs:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Error status (message or boolean)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">        </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interfaces:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">void ThinLTO::writeToFile(const char* path, const char* triple, std::string &errMsg) /* libLTO C++ */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">lto_bool_t lto_thinlto_write_to_file(const char* path, const char* triple) /* libLTO C */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">std::error_code ThinLTOObjectFile::writeToFile(const char* path, const char* triple)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">  </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Notes:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The triple is non-null in the case where we are writing native-wrapped bitcode, and is used to construct the appropriate MCStreamer object.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The gold plugin will interact directly with ThinLTOObjectFile instead of the libLTO ThinLTO class, as it does with IRObjectFile.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The libLTO interfaces will invoke the ThinLTOObjectFile method</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Leverages the same underlying writers as #1</span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="kix-line-break"><br class="kix-line-break"></span></p></li></ul><ol style="margin-top:0pt;margin-bottom:0pt" start="3"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">ThinLTO intermediate file identification</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface checks if an file or memory buffer contains a ThinLTO function index/summary. File (possibly in memory buffer) can contain either bitcode only or native object wrapped bitcode.</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">     </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Input:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">File or memory buffer to check</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">  </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Boolean</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">   </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interfaces:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static bool ThinLTO::hasThinLTOIndexInFile(const char *path) /* libLTO C++ */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static bool ThinLTO::hasThinLTOIndexInFile(const void *mem, size_t length)  /* libLTO C++ */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">lto_bool_t lto_has_thinlto_index(const char *path) /* libLTO C */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">lto_bool_t lto_has_thinlto_index_in_memory(const void *mem, size_t length) /* libLTO C */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static bool ThinLTOObjectFile::hasThinLTOInMemBuffer(MemoryBufferRef Object)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br></span></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">      </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;white-space:pre-wrap;background-color:transparent">Notes:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The libLTO routines invoke the ThinLTOObjectFile function that checks for ThinLTO function index/summary information using format-specific readers.</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The gold plugin will interact directly with ThinLTOObjectFile instead of the libLTO ThinLTO class, as it does with IRObjectFile.</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="4"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Read per-module index/summary from intermediate file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface will read and parse the ThinLTO function index/summary from an intermediate file (possibly in memory) for a module (either bitcode only or native object wrapped).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">  </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">File or memory buffer to check</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre"> </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary for module (format discussed below)</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Error status (libLTO C interfaces set sLastErrorString)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">  </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interfaces:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static ThinLTO * ThinLTO::createFromFile(const char *path, std::string &errMsg) /* libLTO C++ */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static ThinLTO * ThinLTO::createFromOpenFile(int fd, const char *path, size_t size, std::string &errMsg) /* libLTO C++ */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static ThinLTO * ThinLTO::createFromBuffer(const void *mem, const char *path, size_t length, std::string &errMsg) /* libLTO C++ */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">thin_lto_t lto_thinlto_create(const char *path) /* libLTO C */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">thin_lto_t lto_thinlto_create_from_fd(int fd, const char *path, size_t size) /* libLTO C */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">thin_lto_t lto_thinlto_create_from_memory(const void *mem, const char *path, size_t length) /* libLTO C */</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static ErrorOr<std::unique_ptr<ThinLTOObjectFile>> object::ThinLTOObjectFile::create(MemoryBufferRef Object, bool ReadFuncSummaryData = true)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre"> </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Notes:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The optional ReadFuncSummaryData boolean flag to ThinLTOObjectFile::create is used to support the interface discussed below in #6, but is true in this context.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The libLTO routines invoke the ThinLTOObjectFile function that reads the given function index/summary by invoking format-specific readers/parsers. The resulting ThinLTOObjectFile is saved in new ThinLTO object.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The gold plugin will interact directly with ThinLTOObjectFile instead of the libLTO ThinLTO class, as it does with IRObjectFile</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="5"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Read entire combined index/summary file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface will read and parse the combined function index/summary file. The file format will depend on the format of the intermediate files (bitcode only or native object wrapped). Invoked from compiler during ThinLTO importing (so no libLTO interfaces).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">        </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Combined index/summary file in memory buffer</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Boolean indicating whether to read function summary data (in addition to symbol table), true by default and in this context.</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">        </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTO function index/summary object (wrapped in ErrorOr)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">        </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interface:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static ErrorOr<std::unique_ptr<ThinLTOObjectFile>> object::ThinLTOObjectFile::create(MemoryBufferRef Object, bool ReadFuncSummaryData = true)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">      </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Notes:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This is the same ThinLTOObjectFile interface shown above in #4.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The optional ReadFuncSummaryData boolean flag is used to support the interface discussed below in #6, but is true in this context.</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><ol style="margin-top:0pt;margin-bottom:0pt" start="6"><li dir="ltr" style="list-style-type:decimal;font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><h4 dir="ltr" style="line-height:1.38;margin-top:8pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:'Trebuchet MS';color:#666666;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">Read given function from combined index/summary file</span></h4></li></ol><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt;margin-left:36pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This interface will read and parse the combined function index/summary file, parsing and populating the summary information for a single given function. The file format will depend on the format of the intermediate files (bitcode only or native object wrapped).</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">       </span><span style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666666666667px;line-height:1.38;text-indent:36pt;white-space:pre-wrap;background-color:transparent">Inputs:</span><br><ul style="margin-top:0pt;margin-bottom:0pt"><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Combined index/summary file in memory buffer</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Function name</span></p></li><li style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ThinLTOObjectFile object (partially populated)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">  </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Output:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Error status</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">   </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Side Effect:</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">The ThinLTOFunctionInfo entry for the given function is populated in the given ThinLTOObjectFile</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">     </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Interfaces (2 steps):</span></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">static ErrorOr<std::unique_ptr<ThinLTOObjectFile>> object::ThinLTOObjectFile::create(MemoryBufferRef Object, false /*bool ReadFuncSummaryData = true*/)</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">std::error_code ThinLTOObjectFile::findThinLTOFunctionInfoInMemBuffer(MemoryBufferRef Object, StringRef FunctionName)</span></p></li></ul><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><b style="font-weight:normal"><br></b></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><span class="Apple-tab-span" style="white-space:pre">     </span></span><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Notes:</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"></p><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">This usage model requires first reading the ThinLTO symbol table information using the first interface ThinLTOObjectFile::create (same interface as in #5/#6), but with ReadFuncSummaryData=false. In that case the resulting ThinLTOObjectFile object is not fully populated. Specifically, the ThinLTOFunctionInfo entries are not yet populated with the bitcode index and function summary information.</span></p></li><li dir="ltr" style="list-style-type:disc;font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline"><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:14.666666666666666px;font-family:Arial;color:#000000;background-color:transparent;font-weight:normal;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Subsequent invocations to read specific function summaries use the second interface.</span></p></li></ul></span></div><div></div><div><div><span class="Apple-tab-span" style="color:rgb(0,0,0);font-family:Arial;font-size:14.6666669845581px;line-height:20.2399997711182px;white-space:pre">        </span><br></div>-- <br><div class="gmail_signature"><span style="font-family:Times;font-size:medium"><table cellspacing="0" cellpadding="0"><tbody><tr style="color:rgb(85,85,85);font-family:sans-serif;font-size:small"><td nowrap style="border-top-style:solid;border-top-color:rgb(213,15,37);border-top-width:2px">Teresa Johnson |</td><td nowrap style="border-top-style:solid;border-top-color:rgb(51,105,232);border-top-width:2px"> Software Engineer |</td><td nowrap style="border-top-style:solid;border-top-color:rgb(0,153,57);border-top-width:2px"> <a href="mailto:tejohnson@google.com" target="_blank">tejohnson@google.com</a> |</td><td nowrap style="border-top-style:solid;border-top-color:rgb(238,178,17);border-top-width:2px"> 408-460-2413</td></tr></tbody></table></span></div>
</div></div>