[PATCH] D18636: [PGO] Avoid instrumenting constants at value sites

[Betul Buyukkurt via cfe-commits]

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Value profiling should not profile constants and/or constant expressions when they appear as callees in call instructions. Constant expressions form when a direct callee has bitcasts or inttoptr(ptrtint (callee)) nests surrounding it. Value profiling should avoid instrumenting such cases. Mostly NFC.


Repository:
  rL LLVM

http://reviews.llvm.org/D18636

Files:
  lib/CodeGen/CodeGenPGO.cpp
  test/Profile/c-avoid-direct-call.c

Index: test/Profile/c-avoid-direct-call.c
===================================================================
--- /dev/null
+++ test/Profile/c-avoid-direct-call.c
@@ -0,0 +1,11 @@
+// Check the value profiling instrinsics emitted by instrumentation.
+
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.9 -main-file-name c-avoid-direct-call.c %s -o - -emit-llvm -fprofile-instrument=clang -mllvm -enable-value-profiling | FileCheck %s
+
+void foo();
+
+int main(void) {
+// CHECK-NOT: call void @__llvm_profile_instrument_target(i64 ptrtoint (void (...)* @foo to i64), i8* bitcast ({{.*}}* @__profd_main to i8*), i32 0)
+  foo(21);
+  return 0;
+}
Index: lib/CodeGen/CodeGenPGO.cpp
===================================================================
--- lib/CodeGen/CodeGenPGO.cpp
+++ lib/CodeGen/CodeGenPGO.cpp
@@ -755,6 +755,9 @@
   if (!ValuePtr || !ValueSite || !Builder.GetInsertBlock())
     return;
 
+  if (dyn_cast<llvm::Constant>(ValuePtr))
+    return;
+
   bool InstrumentValueSites = CGM.getCodeGenOpts().hasProfileClangInstr();
   if (InstrumentValueSites && RegionCounterMap) {
     auto BuilderInsertPoint = Builder.saveIP();


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