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

[Nicolai Hähnle]

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",
-- 
2.7.4