r296245 - Retry: [profiling] Fix profile counter increment when emitting selects (PR32019)
Vedant Kumar via cfe-commits
cfe-commits at lists.llvm.org
Fri Feb 24 22:35:45 PST 2017
Author: vedantk
Date: Sat Feb 25 00:35:45 2017
New Revision: 296245
URL: http://llvm.org/viewvc/llvm-project?rev=296245&view=rev
Log:
Retry: [profiling] Fix profile counter increment when emitting selects (PR32019)
2nd attempt: the first was in r296231, but it had a use after lifetime
bug.
Clang has logic to lower certain conditional expressions directly into llvm
select instructions. However, it does not emit the correct profile counter
increment as it does this: it emits an unconditional increment of the counter
for the 'then branch', even if the value selected is from the 'else branch'
(this is PR32019).
That means, given the following snippet, we would report that "0" is selected
twice, and that "1" is never selected:
int f1(int x) {
return x ? 0 : 1;
^2 ^0
}
f1(0);
f1(1);
Fix the problem by using the instrprof_increment_step intrinsic to do the
proper increment.
Added:
cfe/trunk/test/Profile/c-ternary.c
Modified:
cfe/trunk/lib/CodeGen/CGExprScalar.cpp
cfe/trunk/lib/CodeGen/CodeGenFunction.h
cfe/trunk/lib/CodeGen/CodeGenPGO.cpp
cfe/trunk/lib/CodeGen/CodeGenPGO.h
Modified: cfe/trunk/lib/CodeGen/CGExprScalar.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprScalar.cpp?rev=296245&r1=296244&r2=296245&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprScalar.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprScalar.cpp Sat Feb 25 00:35:45 2017
@@ -3414,9 +3414,11 @@ VisitAbstractConditionalOperator(const A
// safe to evaluate the LHS and RHS unconditionally.
if (isCheapEnoughToEvaluateUnconditionally(lhsExpr, CGF) &&
isCheapEnoughToEvaluateUnconditionally(rhsExpr, CGF)) {
- CGF.incrementProfileCounter(E);
-
llvm::Value *CondV = CGF.EvaluateExprAsBool(condExpr);
+ llvm::Value *StepV = Builder.CreateZExtOrBitCast(CondV, CGF.Int64Ty);
+
+ CGF.incrementProfileCounter(E, StepV);
+
llvm::Value *LHS = Visit(lhsExpr);
llvm::Value *RHS = Visit(rhsExpr);
if (!LHS) {
Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=296245&r1=296244&r2=296245&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Sat Feb 25 00:35:45 2017
@@ -1127,10 +1127,11 @@ private:
uint64_t LoopCount);
public:
- /// Increment the profiler's counter for the given statement.
- void incrementProfileCounter(const Stmt *S) {
+ /// Increment the profiler's counter for the given statement by \p StepV.
+ /// If \p StepV is null, the default increment is 1.
+ void incrementProfileCounter(const Stmt *S, llvm::Value *StepV = nullptr) {
if (CGM.getCodeGenOpts().hasProfileClangInstr())
- PGO.emitCounterIncrement(Builder, S);
+ PGO.emitCounterIncrement(Builder, S, StepV);
PGO.setCurrentStmt(S);
}
Modified: cfe/trunk/lib/CodeGen/CodeGenPGO.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenPGO.cpp?rev=296245&r1=296244&r2=296245&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenPGO.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenPGO.cpp Sat Feb 25 00:35:45 2017
@@ -739,7 +739,8 @@ CodeGenPGO::applyFunctionAttributes(llvm
Fn->setEntryCount(FunctionCount);
}
-void CodeGenPGO::emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S) {
+void CodeGenPGO::emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S,
+ llvm::Value *StepV) {
if (!CGM.getCodeGenOpts().hasProfileClangInstr() || !RegionCounterMap)
return;
if (!Builder.GetInsertBlock())
@@ -747,11 +748,18 @@ void CodeGenPGO::emitCounterIncrement(CG
unsigned Counter = (*RegionCounterMap)[S];
auto *I8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
- Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::instrprof_increment),
- {llvm::ConstantExpr::getBitCast(FuncNameVar, I8PtrTy),
- Builder.getInt64(FunctionHash),
- Builder.getInt32(NumRegionCounters),
- Builder.getInt32(Counter)});
+
+ llvm::Value *Args[] = {llvm::ConstantExpr::getBitCast(FuncNameVar, I8PtrTy),
+ Builder.getInt64(FunctionHash),
+ Builder.getInt32(NumRegionCounters),
+ Builder.getInt32(Counter), StepV};
+ if (!StepV)
+ Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::instrprof_increment),
+ makeArrayRef(Args, 4));
+ else
+ Builder.CreateCall(
+ CGM.getIntrinsic(llvm::Intrinsic::instrprof_increment_step),
+ makeArrayRef(Args));
}
// This method either inserts a call to the profile run-time during
Modified: cfe/trunk/lib/CodeGen/CodeGenPGO.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenPGO.h?rev=296245&r1=296244&r2=296245&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenPGO.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenPGO.h Sat Feb 25 00:35:45 2017
@@ -105,7 +105,8 @@ private:
void emitCounterRegionMapping(const Decl *D);
public:
- void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S);
+ void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S,
+ llvm::Value *StepV);
/// Return the region count for the counter at the given index.
uint64_t getRegionCount(const Stmt *S) {
Added: cfe/trunk/test/Profile/c-ternary.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Profile/c-ternary.c?rev=296245&view=auto
==============================================================================
--- cfe/trunk/test/Profile/c-ternary.c (added)
+++ cfe/trunk/test/Profile/c-ternary.c Sat Feb 25 00:35:45 2017
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.11.0 -x c %s -o - -emit-llvm -fprofile-instrument=clang | FileCheck %s
+
+// PR32019: Clang can lower some ternary operator expressions to select
+// instructions. Make sure we only increment the profile counter for the
+// condition when the condition evaluates to true.
+// CHECK-LABEL: define i32 @f1
+int f1(int x) {
+// CHECK: [[TOBOOL:%.*]] = icmp ne i32 %1, 0
+// CHECK-NEXT: [[STEP:%.*]] = zext i1 [[TOBOOL]] to i64
+// CHECK-NEXT: [[COUNTER:%.*]] = load i64, i64* getelementptr inbounds ([2 x i64], [2 x i64]* @__profc_f1, i64 0, i64 1)
+// CHECK-NEXT: add i64 [[COUNTER]], [[STEP]]
+// CHECK: [[COND:%.*]] = select i1 [[TOBOOL]], i32 0, i32 1
+ return x ? 0 : 1;
+// CHECK: ret i32 [[COND]]
+}
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