[Mesa-dev] [PATCH 1/4] radeon/ac: add ac_emit_imsb helper.

[Edward O'Callaghan]

This series is,
Reviewed-by: Edward O'Callaghan <funfunctor at folklore1984.net>

On 02/16/2017 02:48 PM, Dave Airlie wrote:
> From: Dave Airlie <airlied at redhat.com>
> 
> We want to use a different intrinsic on newer llvm, so move this
> code to a shared area.
> 
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>  src/amd/common/ac_llvm_build.c | 24 ++++++++++++++++++++++++
>  src/amd/common/ac_llvm_build.h |  4 ++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
> index 20216a7..180fd24 100644
> --- a/src/amd/common/ac_llvm_build.c
> +++ b/src/amd/common/ac_llvm_build.c
> @@ -763,3 +763,27 @@ ac_emit_sendmsg(struct ac_llvm_context *ctx,
>  	ac_emit_llvm_intrinsic(ctx, intr_name, ctx->voidt,
>  			       args, 2, 0);
>  }
> +
> +LLVMValueRef
> +ac_emit_imsb(struct ac_llvm_context *ctx,
> +	     LLVMValueRef arg,
> +	     LLVMTypeRef dst_type)
> +{
> +	LLVMValueRef msb = ac_emit_llvm_intrinsic(ctx, "llvm.AMDGPU.flbit.i32",
> +						  dst_type, &arg, 1,
> +						  AC_FUNC_ATTR_READNONE);
> +
> +	/* The HW returns the last bit index from MSB, but NIR/TGSI wants
> +	 * the index from LSB. Invert it by doing "31 - msb". */
> +	msb = LLVMBuildSub(ctx->builder, LLVMConstInt(ctx->i32, 31, false),
> +			   msb, "");
> +
> +	LLVMValueRef all_ones = LLVMConstInt(ctx->i32, -1, true);
> +	LLVMValueRef cond = LLVMBuildOr(ctx->builder,
> +					LLVMBuildICmp(ctx->builder, LLVMIntEQ,
> +						      arg, LLVMConstInt(ctx->i32, 0, 0), ""),
> +					LLVMBuildICmp(ctx->builder, LLVMIntEQ,
> +						      arg, all_ones, ""), "");
> +
> +	return LLVMBuildSelect(ctx->builder, cond, all_ones, msb, "");
> +}
> diff --git a/src/amd/common/ac_llvm_build.h b/src/amd/common/ac_llvm_build.h
> index e88874a..0ff04e4 100644
> --- a/src/amd/common/ac_llvm_build.h
> +++ b/src/amd/common/ac_llvm_build.h
> @@ -182,6 +182,10 @@ void ac_emit_sendmsg(struct ac_llvm_context *ctx,
>  		     uint32_t msg,
>  		     LLVMValueRef wave_id);
>  
> +LLVMValueRef ac_emit_imsb(struct ac_llvm_context *ctx,
> +			  LLVMValueRef arg,
> +			  LLVMTypeRef dst_type);
> +
>  #ifdef __cplusplus
>  }
>  #endif
> 

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