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Don't look past volatile loads. 

A volatile load should block us from trying to coalesce stores.
PR18023

llvm-svn: 195599
This commit is contained in:
Bill Wendling 2013-11-25 05:01:21 +00:00
parent 89d0335a5c
commit e3c48709ed
2 changed files with 34 additions and 0 deletions
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5
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -8703,6 +8703,11 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode* St) {
Index = STn;
break;
} else if (LoadSDNode *Ldn = dyn_cast<LoadSDNode>(NextInChain)) {
if (Ldn->isVolatile()) {
Index = NULL;
break;
}
// Save the load node for later. Continue the scan.
AliasLoadNodes.push_back(Ldn);
NextInChain = Ldn->getChain().getNode();

29
llvm/test/CodeGen/X86/pr18023.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: llc < %s -mtriple x86_64-apple-macosx10.9.0 | FileCheck %s
; PR18023
; CHECK: movl $1, 4(%rax)
; CHECK: movl $1, 4(%rax)
; CHECK: movl $1, 4(%rax)
@c = common global i32 0, align 4
@a = common global [3 x i32] zeroinitializer, align 4
@b = common global i32 0, align 4
@.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
define void @func() {
store i32 1, i32* getelementptr inbounds ([3 x i32]* @a, i64 0, i64 1), align 4
store i32 0, i32* getelementptr inbounds ([3 x i32]* @a, i64 0, i64 0), align 4
%1 = load volatile i32* @b, align 4
store i32 1, i32* getelementptr inbounds ([3 x i32]* @a, i64 0, i64 1), align 4
store i32 0, i32* getelementptr inbounds ([3 x i32]* @a, i64 0, i64 1), align 4
%2 = load volatile i32* @b, align 4
store i32 1, i32* getelementptr inbounds ([3 x i32]* @a, i64 0, i64 1), align 4
store i32 0, i32* getelementptr inbounds ([3 x i32]* @a, i64 0, i64 2), align 4
%3 = load volatile i32* @b, align 4
store i32 3, i32* @c, align 4
%4 = load i32* getelementptr inbounds ([3 x i32]* @a, i64 0, i64 1), align 4
%call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([4 x i8]* @.str, i64 0, i64 0), i32 %4)
ret void
}
declare i32 @printf(i8*, ...)