[LLVMdev] Is this a missed (simple) optimization?

[Tim Northover]

Hi,

If the function was called Test(&B) then the first store would affect
the second load.

Tim.

On Fri, Nov 16, 2012 at 11:58 AM, AnonW <wayne.phillips at gmail.com> wrote:
> I think this is a missed optimization, but maybe I'm missing some significant
> piece of knowledge(!) as to why this might not be optimizable :)  Test
> case...
>
>    int A;  // some global
>    int B;  // some global
>
>    void Test(int *Out)
>    {
>       *Out = A;   // Can't this be optimized away?
>       *Out = B;
>    };
>
> The LLVM backend (tested 3.1 and 3.0 online demo) doesn't optimize away the
> first store, even with O3 level compiling in clang.  Is there some valid
> reason for this?
>
> Any insight appreciated.  Thanks.
>
>
>
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