[Mesa-stable] [Mesa-dev] [PATCH] radeonsi: fix an off-by-one error in the bounds check for max_vertices

[Edward O'Callaghan]

Reviewed-by: Edward O'Callaghan <funfunctor at folklore1984.net>

On 12/07/2016 07:06 AM, Nicolai Hähnle wrote:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
> 
> The spec actually says that calling EmitStreamVertex is undefined when
> you exceed max_vertices. But we do need to avoid trampling over memory
> outside the GSVS ring.
> 
> Cc: mesa-stable at lists.freedesktop.org
> --
> One more thing I noticed on top of all the other GS changes...
> ---
>  src/gallium/drivers/radeonsi/si_shader.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
> index dee2a17..749823d 100644
> --- a/src/gallium/drivers/radeonsi/si_shader.c
> +++ b/src/gallium/drivers/radeonsi/si_shader.c
> @@ -5181,21 +5181,21 @@ static void si_llvm_emit_vertex(
>  				       "");
>  
>  	/* If this thread has already emitted the declared maximum number of
>  	 * vertices, skip the write: excessive vertex emissions are not
>  	 * supposed to have any effect.
>  	 *
>  	 * If the shader has no writes to memory, kill it instead. This skips
>  	 * further memory loads and may allow LLVM to skip to the end
>  	 * altogether.
>  	 */
> -	can_emit = LLVMBuildICmp(gallivm->builder, LLVMIntULE, gs_next_vertex,
> +	can_emit = LLVMBuildICmp(gallivm->builder, LLVMIntULT, gs_next_vertex,
>  				 lp_build_const_int32(gallivm,
>  						      shader->selector->gs_max_out_vertices), "");
>  
>  	bool use_kill = !info->writes_memory;
>  	if (use_kill) {
>  		kill = lp_build_select(&bld_base->base, can_emit,
>  				       lp_build_const_float(gallivm, 1.0f),
>  				       lp_build_const_float(gallivm, -1.0f));
>  
>  		lp_build_intrinsic(gallivm->builder, "llvm.AMDGPU.kill",
> 

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