[Mesa-dev] [PATCH] ac: Use old kill intrinsics for LLVM 6.

[Samuel Pitoiset]

On 01/30/2018 12:03 AM, Bas Nieuwenhuizen wrote:
> llvm.amdgcn.kill is currently broken for SGPRs. The old intrinsic
> had that issue too, but did not fold the preceding comparison into
> the machine instruction in LLVM. As the preceding comparison is
> often a float comparison, this results in a VGPR, essentially hiding
> the issue.
> 
> I have a fix outstanding for LLVM to make the new intrinsic work,
> but as getting stuff reviewed, committed and cherry-picked in LLVM
> takes quite a while, I'd like to be safe and disable the new
> intrinsic with LLVM 6.
> 
> We can always revert when the fix is in LLVM.

Yes, I do agree.

Reviewed-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>

> 
> Fixes: ad2b3b2a9c "ac: replace llvm.AMDGPU.kilp by llvm.amdgcn.kill with LLVM 6"
> ---
> 
> The LLVM fix is available at https://reviews.llvm.org/D42302
> 
>   src/amd/common/ac_llvm_build.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
> index 5e08508fed..a34eda1037 100644
> --- a/src/amd/common/ac_llvm_build.c
> +++ b/src/amd/common/ac_llvm_build.c
> @@ -1479,7 +1479,7 @@ LLVMValueRef ac_build_wqm_vote(struct ac_llvm_context *ctx, LLVMValueRef i1)
>   
>   void ac_build_kill_if_false(struct ac_llvm_context *ctx, LLVMValueRef i1)
>   {
> -	if (HAVE_LLVM >= 0x0600) {
> +	if (HAVE_LLVM >= 0x0700) {
>   		ac_build_intrinsic(ctx, "llvm.amdgcn.kill", ctx->voidt,
>   				   &i1, 1, 0);
>   		return;
>