It looks the original indirect mask was probably copied from
ANV.
Here we drop lowering locals altogether and allow indirects
on inputs where supported.
Sascha Willems demo results:
tessellation ~4000 -> ~4200 fps
---
Radeonsi also does a couple of other things.
1. It sets the following llvm falg:
sscreen->llvm_has_working_vgpr_indexing ? "" : ",-promote-alloca"
2. Lowers indirect outputs on certain hardware:
return sscreen->llvm_has_working_vgpr_indexing ||
/* TCS stores outputs directly to memory. */
shader == PIPE_SHADER_TESS_CTRL;
I'm not sure if we should be doing these things also. Comments?
src/amd/vulkan/radv_shader.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/src/amd/vulkan/radv_shader.c b/src/amd/vulkan/radv_shader.c
index 055787a705..819d33b1ad 100644
--- a/src/amd/vulkan/radv_shader.c
+++ b/src/amd/vulkan/radv_shader.c
@@ -238,23 +238,39 @@ radv_shader_compile_to_nir(struct radv_device *device,
NIR_PASS_V(nir, nir_lower_constant_initializers, ~0);
NIR_PASS_V(nir, nir_lower_system_values);
NIR_PASS_V(nir, nir_lower_clip_cull_distance_arrays);
}
/* Vulkan uses the separate-shader linking model */
nir->info.separate_shader = true;
nir_shader_gather_info(nir, entry_point->impl);
+ /* While it would be nice not to have this flag, we are constrained
+ * by the reality that LLVM 5.0 doesn't have working VGPR indexing
+ * on GFX9.
+ */
+ bool llvm_has_working_vgpr_indexing =
+ device->physical_device->rad_info.chip_class <= VI;
+
+ /* TODO: Indirect indexing of GS inputs is unimplemented.
+ *
+ * TCS and TES load inputs directly from LDS or offchip memory, so
+ * indirect indexing is trivial.
+ */
nir_variable_mode indirect_mask = 0;
- indirect_mask |= nir_var_shader_in;
- indirect_mask |= nir_var_local;
+ if (nir->stage == MESA_SHADER_GEOMETRY ||
+ (nir->stage != MESA_SHADER_TESS_CTRL &&
+ nir->stage != MESA_SHADER_TESS_EVAL &&
+ !llvm_has_working_vgpr_indexing)) {
+ indirect_mask |= nir_var_shader_in;
+ }
nir_lower_indirect_derefs(nir, indirect_mask);
static const nir_lower_tex_options tex_options = {
.lower_txp = ~0,
};
nir_lower_tex(nir, &tex_options);
nir_lower_vars_to_ssa(nir);
--
2.13.6
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