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b96976e30d
This extends the same line of reasoning used in EarlyCSE w/http://reviews.llvm.org/D15352 to the DSE implementation in InstCombine. Key points: * We only remove unordered or simple stores. * The loads producing values consumed by dead stores don't influence whether the store is dead. Differential Revision: http://reviews.llvm.org/D15354 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255932 91177308-0d34-0410-b5e6-96231b3b80d8
234 lines
5.6 KiB
LLVM
234 lines
5.6 KiB
LLVM
; RUN: opt < %s -instcombine -S | FileCheck %s
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define void @test1(i32* %P) {
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store i32 undef, i32* %P
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store i32 123, i32* undef
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store i32 124, i32* null
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ret void
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; CHECK-LABEL: @test1(
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; CHECK-NEXT: store i32 123, i32* undef
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; CHECK-NEXT: store i32 undef, i32* null
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; CHECK-NEXT: ret void
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}
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define void @test2(i32* %P) {
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%X = load i32, i32* %P ; <i32> [#uses=1]
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%Y = add i32 %X, 0 ; <i32> [#uses=1]
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store i32 %Y, i32* %P
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ret void
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; CHECK-LABEL: @test2(
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; CHECK-NEXT: ret void
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}
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;; Simple sinking tests
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; "if then else"
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define i32 @test3(i1 %C) {
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%A = alloca i32
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br i1 %C, label %Cond, label %Cond2
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Cond:
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store i32 -987654321, i32* %A
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br label %Cont
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Cond2:
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store i32 47, i32* %A
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br label %Cont
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Cont:
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%V = load i32, i32* %A
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ret i32 %V
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; CHECK-LABEL: @test3(
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; CHECK-NOT: alloca
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; CHECK: Cont:
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; CHECK-NEXT: %storemerge = phi i32 [ -987654321, %Cond ], [ 47, %Cond2 ]
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; CHECK-NEXT: ret i32 %storemerge
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}
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; "if then"
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define i32 @test4(i1 %C) {
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%A = alloca i32
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store i32 47, i32* %A
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br i1 %C, label %Cond, label %Cont
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Cond:
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store i32 -987654321, i32* %A
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br label %Cont
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Cont:
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%V = load i32, i32* %A
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ret i32 %V
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; CHECK-LABEL: @test4(
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; CHECK-NOT: alloca
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; CHECK: Cont:
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; CHECK-NEXT: %storemerge = phi i32 [ -987654321, %Cond ], [ 47, %0 ]
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; CHECK-NEXT: ret i32 %storemerge
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}
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; "if then"
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define void @test5(i1 %C, i32* %P) {
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store i32 47, i32* %P, align 1
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br i1 %C, label %Cond, label %Cont
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Cond:
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store i32 -987654321, i32* %P, align 1
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br label %Cont
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Cont:
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ret void
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; CHECK-LABEL: @test5(
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; CHECK: Cont:
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; CHECK-NEXT: %storemerge = phi i32
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; CHECK-NEXT: store i32 %storemerge, i32* %P, align 1
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; CHECK-NEXT: ret void
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}
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; PR14753 - merging two stores should preserve the TBAA tag.
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define void @test6(i32 %n, float* %a, i32* %gi) nounwind uwtable ssp {
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entry:
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store i32 42, i32* %gi, align 4, !tbaa !0
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br label %for.cond
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for.cond: ; preds = %for.body, %entry
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%storemerge = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%0 = load i32, i32* %gi, align 4, !tbaa !0
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%cmp = icmp slt i32 %0, %n
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br i1 %cmp, label %for.body, label %for.end
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for.body: ; preds = %for.cond
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%idxprom = sext i32 %0 to i64
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%arrayidx = getelementptr inbounds float, float* %a, i64 %idxprom
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store float 0.000000e+00, float* %arrayidx, align 4, !tbaa !3
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%1 = load i32, i32* %gi, align 4, !tbaa !0
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%inc = add nsw i32 %1, 1
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store i32 %inc, i32* %gi, align 4, !tbaa !0
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br label %for.cond
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for.end: ; preds = %for.cond
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ret void
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; CHECK-LABEL: @test6(
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; CHECK: for.cond:
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; CHECK-NEXT: phi i32 [ 42
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; CHECK-NEXT: store i32 %storemerge, i32* %gi, align 4, !tbaa !0
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}
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define void @dse1(i32* %p) {
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; CHECK-LABEL: dse1
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; CHECK-NEXT: store
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; CHECK-NEXT: ret
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store i32 0, i32* %p
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store i32 0, i32* %p
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ret void
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}
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; Slightly subtle: if we're mixing atomic and non-atomic access to the
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; same location, then the contents of the location are undefined if there's
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; an actual race. As such, we're free to pick either store under the
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; assumption that we're not racing with any other thread.
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define void @dse2(i32* %p) {
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; CHECK-LABEL: dse2
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; CHECK-NEXT: store i32 0, i32* %p
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; CHECK-NEXT: ret
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store atomic i32 0, i32* %p unordered, align 4
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store i32 0, i32* %p
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ret void
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}
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define void @dse3(i32* %p) {
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; CHECK-LABEL: dse3
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; CHECK-NEXT: store atomic i32 0, i32* %p unordered, align 4
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; CHECK-NEXT: ret
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store i32 0, i32* %p
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store atomic i32 0, i32* %p unordered, align 4
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ret void
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}
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define void @dse4(i32* %p) {
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; CHECK-LABEL: dse4
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; CHECK-NEXT: store atomic i32 0, i32* %p unordered, align 4
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; CHECK-NEXT: ret
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store atomic i32 0, i32* %p unordered, align 4
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store atomic i32 0, i32* %p unordered, align 4
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ret void
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}
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; Implementation limit - could remove unordered store here, but
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; currently don't.
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define void @dse5(i32* %p) {
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; CHECK-LABEL: dse5
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; CHECK-NEXT: store
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; CHECK-NEXT: store
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; CHECK-NEXT: ret
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store atomic i32 0, i32* %p unordered, align 4
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store atomic i32 0, i32* %p seq_cst, align 4
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ret void
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}
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define void @write_back1(i32* %p) {
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; CHECK-LABEL: write_back1
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; CHECK-NEXT: ret
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%v = load i32, i32* %p
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store i32 %v, i32* %p
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ret void
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}
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define void @write_back2(i32* %p) {
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; CHECK-LABEL: write_back2
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; CHECK-NEXT: ret
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%v = load atomic i32, i32* %p unordered, align 4
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store i32 %v, i32* %p
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ret void
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}
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define void @write_back3(i32* %p) {
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; CHECK-LABEL: write_back3
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; CHECK-NEXT: ret
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%v = load i32, i32* %p
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store atomic i32 %v, i32* %p unordered, align 4
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ret void
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}
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define void @write_back4(i32* %p) {
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; CHECK-LABEL: write_back4
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; CHECK-NEXT: ret
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%v = load atomic i32, i32* %p unordered, align 4
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store atomic i32 %v, i32* %p unordered, align 4
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ret void
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}
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; Can't remove store due to ordering side effect
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define void @write_back5(i32* %p) {
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; CHECK-LABEL: write_back5
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; CHECK-NEXT: load
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; CHECK-NEXT: store
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; CHECK-NEXT: ret
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%v = load atomic i32, i32* %p unordered, align 4
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store atomic i32 %v, i32* %p seq_cst, align 4
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ret void
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}
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define void @write_back6(i32* %p) {
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; CHECK-LABEL: write_back6
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; CHECK-NEXT: load
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; CHECK-NEXT: ret
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%v = load atomic i32, i32* %p seq_cst, align 4
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store atomic i32 %v, i32* %p unordered, align 4
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ret void
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}
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define void @write_back7(i32* %p) {
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; CHECK-LABEL: write_back7
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; CHECK-NEXT: load
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; CHECK-NEXT: ret
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%v = load atomic volatile i32, i32* %p seq_cst, align 4
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store atomic i32 %v, i32* %p unordered, align 4
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ret void
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}
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!0 = !{!4, !4, i64 0}
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!1 = !{!"omnipotent char", !2}
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!2 = !{!"Simple C/C++ TBAA"}
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!3 = !{!"float", !1}
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!4 = !{!"int", !1}
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