llvm-6502/test/CodeGen/X86/2012-11-28-merge-store-alias.ll
Akira Hatanaka 522877813a [DAGCombine] Fix a bug in MergeConsecutiveStores.
The bug manifests when there are two loads and two stores chained as follows in
a DAG,

(ld v3f32) -> (st f32) -> (ld v3f32) -> (st f32)

and the stores' values are extracted from the preceding vector loads.

MergeConsecutiveStores would replace the first store in the chain with the
merged vector store, which would create a cycle between the merged store node
and the last load node that appears in the chain.

This commits fixes the bug by replacing the last store in the chain instead.

rdar://problem/20275084

Differential Revision: http://reviews.llvm.org/D8849


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234430 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-08 20:34:53 +00:00

53 lines
1.6 KiB
LLVM

; RUN: llc < %s -march=x86-64 -mcpu=corei7 -mtriple=x86_64-pc-win64 | FileCheck %s
; CHECK: merge_stores_can
; CHECK: callq foo
; CHECK: xorps %xmm0, %xmm0
; CHECK-NEXT: movups %xmm0
; CHECK: callq foo
; CHECK: ret
declare i32 @foo([10 x i32]* )
define i32 @merge_stores_can() nounwind ssp {
%object1 = alloca [10 x i32]
%ret0 = call i32 @foo([10 x i32]* %object1) nounwind
%O1_1 = getelementptr [10 x i32], [10 x i32]* %object1, i64 0, i32 1
%O1_2 = getelementptr [10 x i32], [10 x i32]* %object1, i64 0, i32 2
%O1_3 = getelementptr [10 x i32], [10 x i32]* %object1, i64 0, i32 3
%O1_4 = getelementptr [10 x i32], [10 x i32]* %object1, i64 0, i32 4
%ld_ptr = getelementptr [10 x i32], [10 x i32]* %object1, i64 0, i32 9
store i32 0, i32* %O1_1
store i32 0, i32* %O1_2
%ret = load i32, i32* %ld_ptr ; <--- does not alias.
store i32 0, i32* %O1_3
store i32 0, i32* %O1_4
%ret1 = call i32 @foo([10 x i32]* %object1) nounwind
ret i32 %ret
}
; CHECK: merge_stores_cant
; CHECK-NOT: xorps %xmm0, %xmm0
; CHECK-NOT: movups %xmm0
; CHECK: ret
define i32 @merge_stores_cant([10 x i32]* %in0, [10 x i32]* %in1) nounwind ssp {
%O1_1 = getelementptr [10 x i32], [10 x i32]* %in1, i64 0, i32 1
%O1_2 = getelementptr [10 x i32], [10 x i32]* %in1, i64 0, i32 2
%O1_3 = getelementptr [10 x i32], [10 x i32]* %in1, i64 0, i32 3
%O1_4 = getelementptr [10 x i32], [10 x i32]* %in1, i64 0, i32 4
%ld_ptr = getelementptr [10 x i32], [10 x i32]* %in0, i64 0, i32 2
store i32 0, i32* %O1_1
store i32 0, i32* %O1_2
%ret = load i32, i32* %ld_ptr ; <--- may alias
store i32 0, i32* %O1_3
store i32 0, i32* %O1_4
ret i32 %ret
}