[Mesa-dev] [PATCH] ac: fix 16-bit shifts

[Bas Nieuwenhuizen]

On Thu, Mar 21, 2019 at 11:59 AM Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
> This fixes the following LLVM error when ckeckir is set:
> Type too small for ZExt
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  src/amd/common/ac_nir_to_llvm.c | 33 +++++++++++++++++++++------------
>  1 file changed, 21 insertions(+), 12 deletions(-)
>
> diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
> index 3681c07c364..925073efb85 100644
> --- a/src/amd/common/ac_nir_to_llvm.c
> +++ b/src/amd/common/ac_nir_to_llvm.c
> @@ -671,22 +671,31 @@ static void visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
>                 result = LLVMBuildXor(ctx->ac.builder, src[0], src[1], "");
>                 break;
>         case nir_op_ishl:
> -               result = LLVMBuildShl(ctx->ac.builder, src[0],
> -                                     LLVMBuildZExt(ctx->ac.builder, src[1],
> -                                                   LLVMTypeOf(src[0]), ""),
> -                                     "");
> +               if (ac_get_elem_bits(&ctx->ac, LLVMTypeOf(src[1])) < ac_get_elem_bits(&ctx->ac, LLVMTypeOf(src[0])))
> +                       src[1] = LLVMBuildZExt(ctx->ac.builder, src[1],
> +                                              LLVMTypeOf(src[0]), "");
> +               else

Maybe make this an "else if" with the reverse check so we don't do
anything in the == case, for all three instructions?

Otherwise, r-b
> +                       src[1] = LLVMBuildTrunc(ctx->ac.builder, src[1],
> +                                               LLVMTypeOf(src[0]), "");
> +               result = LLVMBuildShl(ctx->ac.builder, src[0], src[1], "");
>                 break;
>         case nir_op_ishr:
> -               result = LLVMBuildAShr(ctx->ac.builder, src[0],
> -                                      LLVMBuildZExt(ctx->ac.builder, src[1],
> -                                                    LLVMTypeOf(src[0]), ""),
> -                                      "");
> +               if (ac_get_elem_bits(&ctx->ac, LLVMTypeOf(src[1])) < ac_get_elem_bits(&ctx->ac, LLVMTypeOf(src[0])))
> +                       src[1] = LLVMBuildZExt(ctx->ac.builder, src[1],
> +                                              LLVMTypeOf(src[0]), "");
> +               else
> +                       src[1] = LLVMBuildTrunc(ctx->ac.builder, src[1],
> +                                               LLVMTypeOf(src[0]), "");
> +               result = LLVMBuildAShr(ctx->ac.builder, src[0], src[1], "");
>                 break;
>         case nir_op_ushr:
> -               result = LLVMBuildLShr(ctx->ac.builder, src[0],
> -                                      LLVMBuildZExt(ctx->ac.builder, src[1],
> -                                                    LLVMTypeOf(src[0]), ""),
> -                                      "");
> +               if (ac_get_elem_bits(&ctx->ac, LLVMTypeOf(src[1])) < ac_get_elem_bits(&ctx->ac, LLVMTypeOf(src[0])))
> +                       src[1] = LLVMBuildZExt(ctx->ac.builder, src[1],
> +                                              LLVMTypeOf(src[0]), "");
> +               else
> +                       src[1] = LLVMBuildTrunc(ctx->ac.builder, src[1],
> +                                               LLVMTypeOf(src[0]), "");
> +               result = LLVMBuildLShr(ctx->ac.builder, src[0], src[1], "");
>                 break;
>         case nir_op_ilt32:
>                 result = emit_int_cmp(&ctx->ac, LLVMIntSLT, src[0], src[1]);
> --
> 2.21.0
>
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