[PGO] Eliminate prof data register calls on FreeBSD platform

[oota-llvm.git] / lib / Transforms / Instrumentation / InstrProfiling.cpp

diff --git a/lib/Transforms/Instrumentation/InstrProfiling.cpp b/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 05a9c8a5dfe549afab3b960be747f8806a289156..a68fd3db6c2e9238ae04bec683a68c38b73f6d1a 100644 (file)
--- a/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -144,7 +144,7 @@ bool InstrProfiling::runOnModule(Module &M) {
 void InstrProfiling::lowerIncrement(InstrProfIncrementInst *Inc) {
   GlobalVariable *Counters = getOrCreateRegionCounters(Inc);
 
-  IRBuilder<> Builder(Inc->getParent(), *Inc);
+  IRBuilder<> Builder(Inc);
   uint64_t Index = Inc->getIndex()->getZExtValue();
   Value *Addr = Builder.CreateConstInBoundsGEP2_64(Counters, 0, Index);
   Value *Count = Builder.CreateLoad(Addr, "pgocount");
@@ -196,13 +196,17 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
   if (It != RegionCounters.end())
     return It->second;
 
-  // Move the name variable to the right section. Make sure it is placed in the
-  // same comdat as its associated function. Otherwise, we may get multiple
-  // counters for the same function in certain cases.
+  // Move the name variable to the right section. Place them in a COMDAT group
+  // if the associated function is a COMDAT. This will make sure that
+  // only one copy of counters of the COMDAT function will be emitted after
+  // linking.
   Function *Fn = Inc->getParent()->getParent();
+  Comdat *ProfileVarsComdat = nullptr;
+  if (Fn->hasComdat())
+    ProfileVarsComdat = M->getOrInsertComdat(StringRef(getVarName(Inc, "vars")));
   Name->setSection(getNameSection());
   Name->setAlignment(1);
-  Name->setComdat(Fn->getComdat());
+  Name->setComdat(ProfileVarsComdat);
 
   uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
   LLVMContext &Ctx = M->getContext();
@@ -215,7 +219,7 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
   Counters->setVisibility(Name->getVisibility());
   Counters->setSection(getCountersSection());
   Counters->setAlignment(8);
-  Counters->setComdat(Fn->getComdat());
+  Counters->setComdat(ProfileVarsComdat);
 
   RegionCounters[Inc->getName()] = Counters;
 
@@ -240,7 +244,7 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
   Data->setVisibility(Name->getVisibility());
   Data->setSection(getDataSection());
   Data->setAlignment(8);
-  Data->setComdat(Fn->getComdat());
+  Data->setComdat(ProfileVarsComdat);
 
   // Mark the data variable as used so that it isn't stripped out.
   UsedVars.push_back(Data);
@@ -253,6 +257,11 @@ void InstrProfiling::emitRegistration() {
   if (Triple(M->getTargetTriple()).isOSDarwin())
     return;
 
+  // Use linker script magic to get data/cnts/name start/end.
+  if (Triple(M->getTargetTriple()).isOSLinux() ||
+      Triple(M->getTargetTriple()).isOSFreeBSD())
+    return;
+
   // Construct the function.
   auto *VoidTy = Type::getVoidTy(M->getContext());
   auto *VoidPtrTy = Type::getInt8PtrTy(M->getContext());
@@ -362,7 +371,7 @@ void InstrProfiling::emitInitialization() {
         Function::Create(SetNameTy, GlobalValue::ExternalLinkage,
                          "__llvm_profile_override_default_filename", M);
 
-    // Create variable for profile name
+    // Create variable for profile name.
     Constant *ProfileNameConst =
         ConstantDataArray::getString(M->getContext(), InstrProfileOutput, true);
     GlobalVariable *ProfileName =