[Mesa-dev] [PATCH] amd/common: run the EarlyCSEMemSSA LLVM pass

[Bas Nieuwenhuizen]

r-b

On Thu, Oct 12, 2017 at 4:39 PM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
> It's recommended by the instruction combining pass, and
> RadeonSI also runs it. The code size should decrease but
> the number of register might increase a little bit.
>
> Though, after comparing the shader stats with DOW3, it
> appears that the number of registers has been decreased and
> it gives a very minor boost (~+1%).
>
> It also improves the raytracing Vulkan demo, 233->245 FPS
> and doesn't seem to affect any other demos.
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  src/amd/common/ac_nir_to_llvm.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
> index 11ba487f37..a700c0c875 100644
> --- a/src/amd/common/ac_nir_to_llvm.c
> +++ b/src/amd/common/ac_nir_to_llvm.c
> @@ -6168,6 +6168,10 @@ static void ac_llvm_finalize_module(struct nir_to_llvm_context * ctx)
>         LLVMAddLICMPass(passmgr);
>         LLVMAddAggressiveDCEPass(passmgr);
>         LLVMAddCFGSimplificationPass(passmgr);
> +#if HAVE_LLVM >= 0x0400
> +       /* This is recommended by the instruction combining pass. */
> +       LLVMAddEarlyCSEMemSSAPass(passmgr);
> +#endif
>         LLVMAddInstructionCombiningPass(passmgr);
>
>         /* Run the pass */
> --
> 2.14.2
>
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