From 2b0e424b2f7131d7f099708c9ddc208f2ba5a751 Mon Sep 17 00:00:00 2001 From: Honggyu Kim Date: Thu, 1 Sep 2016 11:29:21 +0000 Subject: [Frontend] Fix mcount inlining bug Since some profiling tools, such as gprof, ftrace, and uftrace, use -pg option to generate a mcount function call at the entry of each function. Function invocation can be detected by this hook function. But mcount insertion is done before function inlining phase in clang, sometime a function that already has a mcount call can be inlined in the middle of another function. This patch adds an attribute "counting-function" to each function rather than emitting the mcount call directly in frontend so that this attribute can be processed in backend. Then the mcount calls can be properly inserted in backend after all the other optimizations are completed. Link: https://llvm.org/bugs/show_bug.cgi?id=28660 Reviewers: hans, rjmccall, hfinkel, rengolin, compnerd Subscribers: shenhan, cfe-commits Differential Revision: https://reviews.llvm.org/D22666 llvm-svn: 280355 --- clang/lib/CodeGen/CodeGenFunction.cpp | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) (limited to 'clang/lib/CodeGen/CodeGenFunction.cpp') diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp index 94c9fd7ec6c..1cf068fd388 100644 --- a/clang/lib/CodeGen/CodeGenFunction.cpp +++ b/clang/lib/CodeGen/CodeGenFunction.cpp @@ -428,14 +428,6 @@ void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) { EmitNounwindRuntimeCall(F, args); } -void CodeGenFunction::EmitMCountInstrumentation() { - llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); - - llvm::Constant *MCountFn = - CGM.CreateRuntimeFunction(FTy, getTarget().getMCountName()); - EmitNounwindRuntimeCall(MCountFn); -} - // OpenCL v1.2 s5.6.4.6 allows the compiler to store kernel argument // information in the program executable. The argument information stored // includes the argument name, its type, the address and access qualifiers used. @@ -794,8 +786,12 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, if (ShouldInstrumentFunction()) EmitFunctionInstrumentation("__cyg_profile_func_enter"); + // Since emitting the mcount call here impacts optimizations such as function + // inlining, we just add an attribute to insert a mcount call in backend. + // The attribute "counting-function" is set to mcount function name which is + // architecture dependent. if (CGM.getCodeGenOpts().InstrumentForProfiling) - EmitMCountInstrumentation(); + Fn->addFnAttr("counting-function", getTarget().getMCountName()); if (RetTy->isVoidType()) { // Void type; nothing to return. -- cgit v1.2.3