radeonsi: do not kill GS with memory writes
Vertex emits beyond the specified maximum number of vertices are supposed to
have no effect, which is why we used to always kill GS that reached the limit.
However, if the GS also writes to memory (SSBO, atomics, shader images), then
we must keep going and only skip the vertex emit itself.
Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index 9560baf..8827643 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -5256,6 +5256,7 @@
struct si_shader *shader = ctx->shader;
struct tgsi_shader_info *info = &shader->selector->info;
struct gallivm_state *gallivm = bld_base->base.gallivm;
+ struct lp_build_if_state if_state;
LLVMValueRef soffset = LLVMGetParam(ctx->main_fn,
SI_PARAM_GS2VS_OFFSET);
LLVMValueRef gs_next_vertex;
@@ -5273,19 +5274,28 @@
"");
/* If this thread has already emitted the declared maximum number of
- * vertices, kill it: excessive vertex emissions are not supposed to
- * have any effect, and GS threads have no externally observable
- * effects other than emitting vertices.
+ * 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,
lp_build_const_int32(gallivm,
shader->selector->gs_max_out_vertices), "");
- 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",
- ctx->voidt, &kill, 1, 0);
+ 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",
+ ctx->voidt, &kill, 1, 0);
+ } else {
+ lp_build_if(&if_state, gallivm, can_emit);
+ }
for (i = 0; i < info->num_outputs; i++) {
LLVMValueRef *out_ptr =
@@ -5311,6 +5321,7 @@
1, 0, 1, 1, 0);
}
}
+
gs_next_vertex = lp_build_add(uint, gs_next_vertex,
lp_build_const_int32(gallivm, 1));
@@ -5321,6 +5332,9 @@
args[1] = LLVMGetParam(ctx->main_fn, SI_PARAM_GS_WAVE_ID);
lp_build_intrinsic(gallivm->builder, "llvm.SI.sendmsg",
ctx->voidt, args, 2, 0);
+
+ if (!use_kill)
+ lp_build_endif(&if_state);
}
/* Cut one primitive from the geometry shader */
