[Mesa-dev] [PATCH] Revert "radeon/llvm: enable unsafe math for graphics shaders"

[Grigori Goronzy]

Hi,

AFAIR not enabling this makes LLVM generate really slow code in some
common cases. Maybe this is just a bug in LLVM/R600 triggered by unsafe
FP math optimization or some optimization is too eager. Other drivers do
fine with these types of optimization.

What's the impact on performance with unsafe FP math disabled at this time?

Best regards
Grigori

On 17.02.2015 09:15, Michel Dänzer wrote:
> From: Michel Dänzer <michel.daenzer at amd.com>
> 
> This reverts commit 0e9cdedd2e3943bdb7f3543a3508b883b167e427.
> 
> It caused the grass to disappear in The Talos Principle.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89069
> Signed-off-by: Michel Dänzer <michel at daenzer.net>
> ---
>  src/gallium/drivers/radeon/radeon_llvm_emit.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/src/gallium/drivers/radeon/radeon_llvm_emit.c b/src/gallium/drivers/radeon/radeon_llvm_emit.c
> index 0f9dbab..624077c 100644
> --- a/src/gallium/drivers/radeon/radeon_llvm_emit.c
> +++ b/src/gallium/drivers/radeon/radeon_llvm_emit.c
> @@ -80,10 +80,6 @@ void radeon_llvm_shader_type(LLVMValueRef F, unsigned type)
>  	sprintf(Str, "%1d", llvm_type);
>  
>  	LLVMAddTargetDependentFunctionAttr(F, "ShaderType", Str);
> -
> -	if (type != TGSI_PROCESSOR_COMPUTE) {
> -		LLVMAddTargetDependentFunctionAttr(F, "unsafe-fp-math", "true");
> -	}
>  }
>  
>  static void init_r600_target()
> 


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