From: Justin Bogner <mail@justinbogner.com>
Date: Fri, 25 Apr 2014 07:20:05 +0000 (+0000)
Subject: CodeGen: Avoid instrumenting implicit Decls more effectively
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2196195a2a825cf60a455337133969c9870672c1;p=clang

CodeGen: Avoid instrumenting implicit Decls more effectively

We don't assign counters for implicit Decls, but we were emitting code
to increment the (non-existent) counters and adding empty counter
lists in the output. This fixes the checks in assignRegionCounters and
emitInstrumentationData to do the right thing, and adds an assert for
the pathological case of emitting zero counters.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@207203 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CodeGenPGO.cpp b/lib/CodeGen/CodeGenPGO.cpp
index 6991e40f97..9d4aaff888 100644
--- a/lib/CodeGen/CodeGenPGO.cpp
+++ b/lib/CodeGen/CodeGenPGO.cpp
@@ -146,7 +146,7 @@ llvm::GlobalVariable *CodeGenPGO::buildDataVar() {
 }
 
 void CodeGenPGO::emitInstrumentationData() {
-  if (!CGM.getCodeGenOpts().ProfileInstrGenerate)
+  if (!RegionCounters)
     return;
 
   // Build the data.
@@ -803,7 +803,7 @@ void CodeGenPGO::assignRegionCounters(const Decl *D, llvm::Function *Fn) {
   llvm::IndexedInstrProfReader *PGOReader = CGM.getPGOReader();
   if (!InstrumentRegions && !PGOReader)
     return;
-  if (!D)
+  if (D->isImplicit())
     return;
   setFuncName(Fn);
 
@@ -845,6 +845,7 @@ void CodeGenPGO::mapRegionCounters(const Decl *D) {
     Walker.TraverseDecl(const_cast<BlockDecl *>(BD));
   else if (const CapturedDecl *CD = dyn_cast_or_null<CapturedDecl>(D))
     Walker.TraverseDecl(const_cast<CapturedDecl *>(CD));
+  assert(Walker.NextCounter > 0 && "no entry counter mapped for decl");
   NumRegionCounters = Walker.NextCounter;
   FunctionHash = Walker.Hash.finalize();
 }
@@ -920,6 +921,7 @@ void CodeGenPGO::destroyRegionCounters() {
   RegionCounterMap.reset();
   StmtCountMap.reset();
   RegionCounts.reset();
+  RegionCounters = nullptr;
 }
 
 /// \brief Calculate what to divide by to scale weights.
diff --git a/test/Profile/cxx-implicit.cpp b/test/Profile/cxx-implicit.cpp
new file mode 100644
index 0000000000..79840ad938
--- /dev/null
+++ b/test/Profile/cxx-implicit.cpp
@@ -0,0 +1,17 @@
+// Ensure that implicit methods aren't instrumented.
+
+// RUN: %clang_cc1 -x c++ %s -triple %itanium_abi_triple -main-file-name cxx-implicit.cpp -o - -emit-llvm -fprofile-instr-generate | FileCheck %s
+
+// An implicit constructor is generated for Base. We should not emit counters
+// for it.
+// CHECK-NOT: @__llvm_profile_counters__ZN4BaseC2Ev =
+
+struct Base {
+  virtual void foo();
+};
+
+struct Derived : public Base {
+  Derived();
+};
+
+Derived::Derived() {}