From 2196195a2a825cf60a455337133969c9870672c1 Mon Sep 17 00:00:00 2001
From: Justin Bogner <mail@justinbogner.com>
Date: Fri, 25 Apr 2014 07:20:05 +0000
Subject: [PATCH] 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
---
 lib/CodeGen/CodeGenPGO.cpp    |  6 ++++--
 test/Profile/cxx-implicit.cpp | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 test/Profile/cxx-implicit.cpp

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() {}
-- 
2.40.0