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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">>
</span>Sounds good. Please let me know how your experiments go. I'm keen to improve the Orc APIs further, so your feedback would be very welcome.<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">LLILC is using ORC now, and it was a remarkably smooth transition / small change (https://github.com/dotnet/llilc/commit/47513add13980e7a32f9b0ec3d2da3db0911bca2).
The CoreCLR execution engine handles laziness (and symbol resolution) for us, so a straightforward application of IRCompileLayer using SimpleCompiler and ObjectLinkingLayer along the lines of the "initial" orc kaleidoscope example covered our current functionality
neatly.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">There were just two spots that I found myself writing some boilerplate:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">One was in constructing the TargetMachine (to pass to the SimpleCompiler constructor). With MCJit, the EngineBuilder took care of creating the TargetMachine,
and the code to set up the EngineBuilder looked like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> std::unique_ptr<Module> M = ..;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> M->setTargetTriple(LLILC_TARGET_TRIPLE);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> EngineBuilder Builder(std::move(M)); // Builder takes ownership of module<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> std::string ErrStr;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> Builder.setErrorStr(&ErrStr);</span><span style="font-size:8.0pt;font-family:Consolas;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas;color:black">
<span style="background:white;mso-highlight:white">Builder.setOptLevel(/* value depending on what the CLR EE requests */);</span><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> Builder.setTargetOptions(/* value depending on what the CLR EE requests */);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> ExecutionEngine *NewEngine = Builder.create();<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I noticed you used "</span><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">EngineBuilder</span><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">().selectTarget()</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">"
in the kaleidoscope sample, but I couldn't do exactly that for LLILC since we're threading the triple through the module that the builder wants to own, and also it seemed to make sense that we shouldn't need an EngineBuilder if we're not building an Engine,
so I looked at what our Builder had been doing and wound up with this code to instead create the TargetMachine directly:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> std::string ErrStr;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> const llvm::Target *TheTarget =<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> TargetRegistry::lookupTarget(LLILC_TARGET_TRIPLE, ErrStr);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> TargetOptions Options = /* value depending on what the CLR EE requests */;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> CodeGenOpt::Level OptLevel = /* value depending on what the CLR EE requests */;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> TargetMachine *TM = TheTarget->createTargetMachine(<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> LLILC_TARGET_TRIPLE, "", "", Options, Reloc::Default, CodeModel::Default,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> OptLevel);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This tiny amount of boilerplate that I ended up with for creating the TargetMachine seems entirely reasonable, but going through the exercise and looking at
EngineBuilder code (which of course has several more paths than reflected above) made me wonder how much of its logic is for building the TargetMachine and whether pulling it out into a TargetMachineBuilder would be useful to give ORC clients the support that
EngineBuilder gives MCJit clients.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The second spot where I needed some code was getting a SymbolResolver to pass to the ObjectLinkingLayer. In LLILC we actually don't need cross-module symbols
resolved because the CoreCLR execution engine resolves them and gives the Jit raw addresses. So I simply defined a NullResolver like so (I felt it was more readable this way than building an equivalent LambdaResolver):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">/// \brief Stub \p SymbolResolver expecting no resolution requests<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">///<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">/// The ObjectLinkingLayer takes a SymbolResolver ctor parameter.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">/// The CLR EE resolves tokens to addresses for the Jit during IL reading,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">/// so no symbol resolution is actually needed at ObjLinking time.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">class NullResolver : public llvm::RuntimeDyld::SymbolResolver {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">public:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> llvm::RuntimeDyld::SymbolInfo findSymbol(const std::string &Name) final {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> llvm_unreachable("Reader resolves tokens directly to addresses");<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> llvm::RuntimeDyld::SymbolInfo<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> findSymbolInLogicalDylib(const std::string &Name) final {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> llvm_unreachable("Reader resolves tokens directly to addresses");<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">};<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">It occurs to me that if any other ORC clients are in the same boat, they'll need a resolver that look a lot like this, but I think perhaps we're in an unusual
boat.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">One general comment I have is that I wish it were more easily discoverable what the constraints are on the various template parameters in ORC code, both from
the client side (e.g. realizing that SymbolResolverPtrT should be a naked/unique/etc pointer to RuntimeDyld::SymbolResolver or a derived class) and the consumer side (e.g. realizing that an ObjSetHandleT needs to be moved rather than assigned). The comment
on IRCompileLayer mentions that BaseLayerT "</span><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">must implement the object layer concept</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">",
for example, but I wasn't sure what exactly constitutes the object layer concept. I had to dig into that one, as I went on to implement an object layer to satisfy the CoreCLR's requirements on EH frame reporting that started this thread. I figured that implementing
the methods on ObjectLinkingLayer would be a good bet, but approached it by starting with just addObjectSet and adding method implementations as the compiler complained they were missing. With that approach, I never did need to implement findSymbolIn, mapSectionAddress,
or emitAndFinalize, for reasons I haven't dug in to understand. The object layer class I produced in this way was itself mostly boilerplate:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">class ReserveSpaceLayerT {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">public:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> typedef LLILCJit::LoadLayerT::ObjSetHandleT ObjSetHandleT;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> ReserveSpaceLayerT(LLILCJit::LoadLayerT *Loader, llilc::EEMemoryManager *MM) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> this->Loader = Loader;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> this->MM = MM;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> template <typename ObjSetT, typename MemoryManagerPtrT, typename SymbolResolverPtrT><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> ObjSetHandleT addObjectSet(const ObjSetT &Objects,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> MemoryManagerPtrT MemMgr,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> SymbolResolverPtrT Resolver) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> for (const auto& Obj : Objects) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> MM->reserveUnwindSpace(*Obj);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> return Loader->addObjectSet(Objects, MemMgr, Resolver);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> void removeObjectSet(ObjSetHandleT H) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> Loader->removeObjectSet(std::move(H));<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> orc::JITSymbol findSymbol(StringRef Name, bool ExportedSymbolsOnly) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> return Loader->findSymbol(Name, ExportedSymbolsOnly);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> template <typename OwningMBSet><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> void takeOwnershipOfBuffers(ObjSetHandleT H, OwningMBSet MBs) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> Loader->takeOwnershipOfBuffers(std::move(H), std::move(MBs));<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">private:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> LLILCJit::LoadLayerT *Loader;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"> llilc::EEMemoryManager *MM;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white">};<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:8.0pt;font-family:Consolas;color:black;background:white;mso-highlight:white"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I could imagine that abstracting this might make a useful utility -- what I wanted was to call MM->reserveUnwindSpace on each ObjectFile as it passes through,
and otherwise forward everything on to the base layer. Perhaps a LambdaObjectLayer that takes a function<void(const ObjectFile*)> would be appropriate? Let me know if you'd like to see a patch along those lines; I'm happy to contribute back, but don't have
much context on what would be useful for other clients.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-Joseph<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></a></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Lang Hames [mailto:lhames@gmail.com]
<br>
<b>Sent:</b> Monday, June 1, 2015 1:41 PM<br>
<b>To:</b> Joseph Tremoulet<br>
<b>Cc:</b> Russell Hadley; llvmdev@cs.uiuc.edu<br>
<b>Subject:</b> Re: [LLVMdev] MCJit interface question<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Russell, Joseph,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">> <span style="font-size:11.5pt;font-family:"Calibri","sans-serif";color:#993366"> I'll look into moving LLILC to ORC.</span><o:p></o:p></p>
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<p class="MsoNormal">Sounds good. Please let me know how your experiments go. I'm keen to improve the Orc APIs further, so your feedback would be very welcome. <o:p></o:p></p>
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<p class="MsoNormal">Cheers,<o:p></o:p></p>
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<p class="MsoNormal">Lang.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Sat, May 30, 2015 at 11:14 AM, Joseph Tremoulet <<a href="mailto:jotrem@microsoft.com" target="_blank">jotrem@microsoft.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#993366">Agreed, that sounds like the best plan. I'll look into moving LLILC to ORC.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#993366"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#993366">Thanks</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#993366">-Joseph</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="14da608b2f52bd94__MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#993366"> </span></a><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Russell Hadley
<br>
<b>Sent:</b> Friday, May 29, 2015 8:13 PM<br>
<b>To:</b> Lang Hames; Joseph Tremoulet<br>
<b>Cc:</b> <a href="mailto:llvmdev@cs.uiuc.edu" target="_blank">llvmdev@cs.uiuc.edu</a><br>
<b>Subject:</b> RE: [LLVMdev] MCJit interface question</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hey Joseph,
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">What Lang said made me wonder. Is it the right time for us (LLILC) to move to ORC? The long term
plan was to go there but this could be our forcing function.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-R</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">
<a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank">llvmdev-bounces@cs.uiuc.edu</a> [<a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank">mailto:llvmdev-bounces@cs.uiuc.edu</a>]
<b>On Behalf Of </b>Lang Hames<br>
<b>Sent:</b> Friday, May 29, 2015 2:23 PM<br>
<b>To:</b> Joseph Tremoulet<br>
<b>Cc:</b> <a href="mailto:llvmdev@cs.uiuc.edu" target="_blank">llvmdev@cs.uiuc.edu</a><br>
<b>Subject:</b> Re: [LLVMdev] MCJit interface question</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi Joseph,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">There are several reasons that a client might want to access the object before it's loaded, so a general API like #2 seems like the way to go.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">To support this in MCJIT you can add this to the event listener API. Orc clients can already do this by adding a custom object-file layer.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">- Lang.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Fri, May 29, 2015 at 9:05 AM, Joseph Tremoulet <<a href="mailto:jotrem@microsoft.com" target="_blank">jotrem@microsoft.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I think I need to make a small change to the MCJit interface, and would like some feedback on what the most appropriate option would be.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I'm working on LLILC (a jit for the CoreCLR built on MCJit, which creates one module for each MSIL method, containing the main function and zero or more EH handler functions extracted
from the MSIL method). The CoreCLR requires the jit to notify it of the size of the unwind info descriptors for each function in the module
<i>before</i> reserving the memory it will be loaded into. So we need a call (or calls) from the Jit/loader into the MemoryManager that runs at-or-before reserveAllocationSpace, is conceptually similar to registerEHFrames in that it's reserving EH frames,
but that additionally needs to separate out the per-function information.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">A few options come to mind:<o:p></o:p></p>
<p>1.<span style="font-size:7.0pt"> </span>Add a needsToReserveEHFrames callback on MemoryManager (to parallel needsToReserveAllocationSpace), and a reserveEHFrames callback (parallel to registerEHFrames) that the loader would use to notify the memory
manager if needsToReserveEHFrames() is true. This seems at a high-level the most straightforward fit for the LLILC requirement, but I don't know if for other targets it would even be possible to move the identification of EH frames (which depends on the 'LocalSections'
computed in loadObjectImpl) to before calling reserveAllocationSpace. I also don't know if that would be an undesirable "tight coupling" of RuntimeDyld with CoreCLR's particular interface. (and note that this is really two options, in that the code to separate
out the per-function EH frame contribution could go in either the client memory manager or in the loader.)<o:p></o:p></p>
<p>2.<span style="font-size:7.0pt"> </span>Add a notification similar to NotifyObjectEmitted, but which runs just
<i>before</i> the call to Dyld.loadObject. Something like NotifyObjectPreLoaded. The LLILC-specific MemoryManager could use this hook to scan the object::ObjectFile and pass whatever it needs to the CoreCLR. This seems like a decent option to me, but I don't
know if it would be considered a bad loss of encapsulation to passs out the object::ObjectFile in the state where it's been 'created' but not yet 'loaded'.<o:p></o:p></p>
<p>3.<span style="font-size:7.0pt"> </span>Similar to #2, the existing reserveAllocationSpace callback on MemoryManager could simply take an additional parameter which is the object::ObjectFile. This would be a more minimal change than #2 in terms of
how much surface area it adds to the MCJit interface, but also a more invasive change in that all MemoryManager implementations would need to be updated with the reserveAllocationSpace signature change (though they could just ignore the new parameter).<o:p></o:p></p>
<p>4.<span style="font-size:7.0pt"> </span>We could avoid needing to crack the object file for this information altogether; MCJit could add a hook where a client could insert passes into the PassManager used in emitObject; LLILC could attach a pass that
would consult the MachineModuleInfo, where this information could be stored (it's similar to what's stored in the WinEHFuncInfos hanging off the MMI today). But adding hooks for client passes might be opening a can of worms…<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">My inclination would be #2 or #3, but I would love some feedback on which of the tradeoffs seem most agreeable (and/or what options I've overlooked).<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#888888">-Joseph</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#888888"> </span><o:p></o:p></p>
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