[llvm-dev] SROA and volatile memcpy/memset

[Krzysztof Parzyszek via llvm-dev]

On 11/11/2015 8:53 AM, Hal Finkel wrote:
>
> SROA seems to be doing a number of things here. What about if we prevented SROA from generating multiple slices splitting volatile accesses? There might be a significant difference between that and something like this test (test/Transforms/SROA/basictest.ll):
>
> define i32 @test6() {
> ; CHECK-LABEL: @test6(
> ; CHECK: alloca i32
> ; CHECK-NEXT: store volatile i32
> ; CHECK-NEXT: load i32, i32*
> ; CHECK-NEXT: ret i32
>
> entry:
>    %a = alloca [4 x i8]
>    %ptr = getelementptr [4 x i8], [4 x i8]* %a, i32 0, i32 0
>    call void @llvm.memset.p0i8.i32(i8* %ptr, i8 42, i32 4, i32 1, i1 true)
>    %iptr = bitcast i8* %ptr to i32*
>    %val = load i32, i32* %iptr
>    ret i32 %val
> }
>


Yes, that would work.

-Krzysztof

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