From: Wei Mi <wmi@google.com>
Date: Wed, 23 Sep 2015 22:40:45 +0000 (+0000)
Subject: Put profile variables of COMDAT functions to it's own COMDAT group.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2f1d7a4c890b42b40a3102029074cd465b70dbb7;p=oota-llvm.git

Put profile variables of COMDAT functions to it's own COMDAT group.

In -fprofile-instr-generate compilation, to remove the redundant profile
variables for the COMDAT functions, these variables are placed in the same
COMDAT group as its associated function. This way when the COMDAT function
is not picked by the linker, those profile variables will also not be
output in the final binary. This may cause warning when mix link objects
built w and wo -fprofile-instr-generate.

This patch puts the profile variables for COMDAT functions to its own COMDAT
group to avoid the problem.

Patch by xur.
Differential Revision: http://reviews.llvm.org/D12248


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248440 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Instrumentation/InstrProfiling.cpp b/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 712bf8edc7e..8ecfda64f1d 100644
--- a/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -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);
diff --git a/test/Instrumentation/InstrProfiling/PR23499.ll b/test/Instrumentation/InstrProfiling/PR23499.ll
index 5aae735120b..8988a9aa3be 100644
--- a/test/Instrumentation/InstrProfiling/PR23499.ll
+++ b/test/Instrumentation/InstrProfiling/PR23499.ll
@@ -8,9 +8,9 @@ $_Z3barIvEvv = comdat any
 
 @__llvm_profile_name__Z3barIvEvv = linkonce_odr hidden constant [11 x i8] c"_Z3barIvEvv", align 1
 
-; CHECK: @__llvm_profile_name__Z3barIvEvv = linkonce_odr hidden constant [11 x i8] c"_Z3barIvEvv", section "{{.*}}__llvm_prf_names", comdat($_Z3barIvEvv), align 1
-; CHECK: @__llvm_profile_counters__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}__llvm_prf_cnts", comdat($_Z3barIvEvv), align 8
-; CHECK: @__llvm_profile_data__Z3barIvEvv = linkonce_odr hidden constant { i32, i32, i64, i8*, i64* } { i32 11, i32 1, i64 0, i8* getelementptr inbounds ([11 x i8], [11 x i8]* @__llvm_profile_name__Z3barIvEvv, i32 0, i32 0), i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__llvm_profile_counters__Z3barIvEvv, i32 0, i32 0) }, section "{{.*}}__llvm_prf_data", comdat($_Z3barIvEvv), align 8
+; CHECK: @__llvm_profile_name__Z3barIvEvv = linkonce_odr hidden constant [11 x i8] c"_Z3barIvEvv", section "{{.*}}__llvm_prf_names", comdat($__llvm_profile_vars__Z3barIvEvv), align 1
+; CHECK: @__llvm_profile_counters__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}__llvm_prf_cnts", comdat($__llvm_profile_vars__Z3barIvEvv), align 8
+; CHECK: @__llvm_profile_data__Z3barIvEvv = linkonce_odr hidden constant { i32, i32, i64, i8*, i64* } { i32 11, i32 1, i64 0, i8* getelementptr inbounds ([11 x i8], [11 x i8]* @__llvm_profile_name__Z3barIvEvv, i32 0, i32 0), i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__llvm_profile_counters__Z3barIvEvv, i32 0, i32 0) }, section "{{.*}}__llvm_prf_data", comdat($__llvm_profile_vars__Z3barIvEvv), align 8
 
 declare void @llvm.instrprof.increment(i8*, i64, i32, i32) #1