[Mesa-dev] [PATCH] radeonsi: disable sinking common instructions down to the end block

[Marek Olšák]

On Wed, Mar 15, 2017 at 1:21 AM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
> Initially this was a workaround for a bug introduced in LLVM 4.0
> in the SimplifyCFG pass that caused image instrinsics to disappear
> (because they were badly sunk). Finally, this is a win because it
> decreases SGPR spilling and increases the number of waves a bit.
>
> Although, shader-db results are good I think we might want to
> remove it in the future once the issue is fixed. For now, enable
> it for LLVM >= 4.0.
>
> This also fixes a rendering issue with the speedometer in Dirt Rally.
>
> More information can be found here https://reviews.llvm.org/D26348.
>
> Thanks to Dave Airlie for the patch.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99484
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>
> For those interested, here's the full shader-db report:
>
> https://hastebin.com/osepehehat.pas
>
>  src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
> index 5c63b732b3..4fb7a126e4 100644
> --- a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
> +++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
> @@ -40,6 +40,7 @@
>  #include <stdio.h>
>  #include <llvm-c/Transforms/IPO.h>
>  #include <llvm-c/Transforms/Scalar.h>
> +#include <llvm-c/Support.h>
>
>  /* Data for if/else/endif and bgnloop/endloop control flow structures.
>   */
> @@ -124,6 +125,11 @@ static void init_amdgpu_target()
>         LLVMInitializeAMDGPUTarget();
>         LLVMInitializeAMDGPUTargetMC();
>         LLVMInitializeAMDGPUAsmPrinter();
> +
> +#if HAVE_LLVM >= 0x0400
> +       const char *argv[2] = {"mesa", "-simplifycfg-sink-common=false"};
> +       LLVMParseCommandLineOptions(2, argv, NULL);
> +#endif

Would it possible to do:
if (HAVE_LLVM >= 0x0400) {
...
}

Also, Cc stable?

With those done:
Reviewed-by: Marek Olšák <marek.olsak at amd.com>

Marek



>  }
>
>  static once_flag init_amdgpu_target_once_flag = ONCE_FLAG_INIT;
> --
> 2.12.0
>
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