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<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Yes, sorry that I wasn’t very clear about that, but the hack in opt.cpp only works when using opt. We are doing the “early rewrites” when using another frontend than clang, and in that
case we are running the opt/llc binaries standalone after the frontend.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">I’m not sure, but maybe it is possible to do something similar in EmitAssemblyHelper::CreatePasses (in clang/lib/CodeGen/BackendUtil.cpp), if you want to do it in clang.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">/Björn<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Son Tuan VU <sontuan.vu119@gmail.com>
<br>
<b>Sent:</b> den 12 juni 2018 19:54<br>
<b>To:</b> Björn Pettersson A <bjorn.a.pettersson@ericsson.com><br>
<b>Subject:</b> Re: [llvm-dev] ModulePass cannot be registered as EarlyAsPossible<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Thanks Björn for your answer.<o:p></o:p></p>
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<p class="MsoNormal">So your way of doing this implies that we have to use opt, what if we want to use clang instead? I mean, instead of
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<b>clang -O0 -emit-llvm -S foo.c -o foo.ll</b><o:p></o:p></p>
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<p class="MsoNormal"><b>opt -O1 -S foo.ll -o foo_opt.ll</b><o:p></o:p></p>
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<p class="MsoNormal">we would have<o:p></o:p></p>
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<p class="MsoNormal"><b>clang -O1 -emit-llvm -S foo.c -o foo_opt.ll</b><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I guess this requires me to find the right place in clang to add the same code as yours in opt?<br>
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<o:p></o:p></p>
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<p class="MsoNormal">Son Tuan Vu<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 Tue, Jun 12, 2018 at 6:11 PM, Björn Pettersson A <<a href="mailto:bjorn.a.pettersson@ericsson.com" target="_blank">bjorn.a.pettersson@ericsson.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 lang="EN-US">I let someone else answer about if it is a bug or not.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Anyway, in our out-of-tree-target we have some module passes that we want to run early in opt.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Our way of doing it is to use a hack in tools/opt/opt.cpp like this:</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">index 43771d5d75b..2a08ce1a448 100644</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">--- a/tools/opt/opt.cpp</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+++ b/tools/opt/opt.cpp</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">@@ -608,6 +608,16 @@ int main(int argc, char **argv) {</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> OptCustomPassManager Passes;</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> bool AddOneTimeDebugifyPasses = EnableDebugify && !DebugifyEach;</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ // EarlyRewriter must run very early. Since we made it a</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ // ModulePass, there is no standard way to make this happen (the standard ways</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ // only work for FunctionPasses). Run the pass in a separate Passmanager</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ // before any other pass.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ if (TM && TM->runEarlyModulePasses()) {</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ legacy::PassManager FirstPasses;</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ addPass(FirstPasses, static_cast<ModulePass*>(createEarlyRewriterPass()));</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ FirstPasses.run(*M);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+ }</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">+</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> // Add an appropriate TargetLibraryInfo pass for the module's triple.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> TargetLibraryInfoImpl TLII(ModuleTriple);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Note the FirstPasses.run(*M), which means that those first passes are run directly.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">And then we have added the runEarlyModulePasses() hook in TargetMachine that will make sure we add and run the FirstPasses pass manager when compiling for our
target.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Regards,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Björn</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><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 lang="EN-US">From:</span></b><span lang="EN-US"> llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>>
<b>On Behalf Of </b>Son Tuan VU via llvm-dev<br>
<b>Sent:</b> den 12 juni 2018 15:46<br>
<b>To:</b> llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>><br>
<b>Subject:</b> [llvm-dev] ModulePass cannot be registered as EarlyAsPossible</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>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hello all,<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">I've followed the example in <a href="https://github.com/CompilerTeaching/SimplePass/blob/master/SimplePass.cc" target="_blank">https://github.com/CompilerTeaching/SimplePass/blob/master/SimplePass.cc</a>
in order to create a custom pass.<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">The pass needs to be added before any transformation, so I used EP_EarlyAsPossible extension point to register it. Furthermore, I need to access to every GlobalVariable in the
IR, so my pass has to be a ModulePass, like this:<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"> struct MyPass : public ModulePass {<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> static char ID;<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> MyPass(): ModulePass(ID) {}<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> virtual bool runOnModule(Module &M) {...}<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">However, every time I try to access to the Module object M inside runOnModule(), clang just crashes. Even a debug message like
<b>outs() << M.getName() << '\n';</b> would cause a segfault. So am I doing something wrong, like EP_EarlyAsPossible is really not to be used with ModulePasses, or is this rather a bug?<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">In case this is not a bug, what would be the best way to manipulate an IR Module as it is coming right out of the frontend?<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">Thanks for your help,<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">Son Tuan Vu<o:p></o:p></p>
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