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Do not optimize atomic load to non-atomic memcmp 

Differential Revision: https://reviews.llvm.org/D51998

llvm-svn: 342498
This commit is contained in:
Christy Lee 2018-09-18 17:02:42 +00:00
parent f5a2848376
commit c85da8bd9a
2 changed files with 50 additions and 2 deletions
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5
llvm/lib/Transforms/Scalar/MergeICmps.cpp
View File

@ -81,8 +81,9 @@ BCEAtom visitICmpLoadOperand(Value *const Val) {
LLVM_DEBUG(dbgs() << "used outside of block\n");
return {};
}
if (LoadI->isVolatile()) {
LLVM_DEBUG(dbgs() << "volatile\n");
// Do not optimize atomic loads to non-atomic memcmp
if (!LoadI->isSimple()) {
LLVM_DEBUG(dbgs() << "volatile or atomic\n");
return {};
}
Value *const Addr = LoadI->getOperand(0);

47
llvm/test/Transforms/MergeICmps/X86/atomic.ll Normal file
View File

@ -0,0 +1,47 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s
%"struct.std::pair" = type { i32, i32 }
define zeroext i1 @opeq(
; CHECK-LABEL: @opeq(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[FIRST_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A:%.*]], i64 0, i32 0
; CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* [[FIRST_I]], align 4
; CHECK-NEXT: [[FIRST1_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B:%.*]], i64 0, i32 0
; CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* [[FIRST1_I]], align 4
; CHECK-NEXT: [[CMP_I:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
; CHECK-NEXT: br i1 [[CMP_I]], label [[LAND_RHS_I:%.*]], label [[OPEQ1_EXIT:%.*]]
; CHECK: land.rhs.i:
; CHECK-NEXT: [[SECOND_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A]], i64 0, i32 1
; CHECK-NEXT: [[TMP2:%.*]] = load atomic i32, i32* [[SECOND_I]] seq_cst, align 4
; CHECK-NEXT: [[SECOND2_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B]], i64 0, i32 1
; CHECK-NEXT: [[TMP3:%.*]] = load i32, i32* [[SECOND2_I]], align 4
; CHECK-NEXT: [[CMP3_I:%.*]] = icmp eq i32 [[TMP2]], [[TMP3]]
; CHECK-NEXT: br label [[OPEQ1_EXIT]]
; CHECK: opeq1.exit:
; CHECK-NEXT: [[TMP4:%.*]] = phi i1 [ false, [[ENTRY:%.*]] ], [ [[CMP3_I]], [[LAND_RHS_I]] ]
; CHECK-NEXT: ret i1 [[TMP4]]
;
%"struct.std::pair"* nocapture readonly dereferenceable(8) %a,
%"struct.std::pair"* nocapture readonly dereferenceable(8) %b) local_unnamed_addr #0 {
entry:
%first.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 0
%0 = load i32, i32* %first.i, align 4
%first1.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 0
%1 = load i32, i32* %first1.i, align 4
%cmp.i = icmp eq i32 %0, %1
br i1 %cmp.i, label %land.rhs.i, label %opeq1.exit
land.rhs.i:
%second.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 1
%2 = load atomic i32, i32* %second.i seq_cst, align 4
%second2.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 1
%3 = load i32, i32* %second2.i, align 4
%cmp3.i = icmp eq i32 %2, %3
br label %opeq1.exit
opeq1.exit:
%4 = phi i1 [ false, %entry ], [ %cmp3.i, %land.rhs.i ]
ret i1 %4
}