radv: do nir_lower_bit_size after algebraic optimizations

There are too many algebraic optimizations to be certain that one of them
couldn't create instructions which need lowering. It also creates better
code for some reason.

fossil-db (parallel-rdp, Navi):
Totals from 217 (31.77% of 683) affected shaders:
VGPRs: 7716 -> 7672 (-0.57%)
CodeSize: 1516152 -> 1510688 (-0.36%); split: -0.38%, +0.02%
MaxWaves: 3964 -> 3982 (+0.45%)
Instrs: 269445 -> 268508 (-0.35%); split: -0.36%, +0.02%
Cycles: 37963416 -> 37912592 (-0.13%); split: -0.15%, +0.01%

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4791>

diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
index 7585829..61ec858 100644 (file)
--- a/src/amd/vulkan/radv_pipeline.c
+++ b/src/amd/vulkan/radv_pipeline.c
@@ -3147,9 +3147,6 @@ VkResult radv_create_shaders(struct radv_pipeline *pipeline,
                        if (!radv_use_llvm_for_stage(device, i))
                                nir_lower_int64(nir[i]);
 
-                       if (nir_lower_bit_size(nir[i], lower_bit_size_callback, NULL))
-                               nir_copy_prop(nir[i]); /* allow nir_opt_idiv_const() to optimize lowered divisions */
-
                        /* TODO: Implement nir_op_uadd_sat with LLVM. */
                        if (!radv_use_llvm_for_stage(device, i))
                                nir_opt_idiv_const(nir[i], 32);
@@ -3181,6 +3178,12 @@ VkResult radv_create_shaders(struct radv_pipeline *pipeline,
                                NIR_PASS_V(nir[i], nir_opt_cse);
                        }
 
+                       if (nir_lower_bit_size(nir[i], lower_bit_size_callback, NULL)) {
+                               nir_lower_idiv(nir[i], nir_lower_idiv_precise);
+                               nir_opt_constant_folding(nir[i]);
+                               nir_opt_dce(nir[i]);
+                       }
+
                        /* cleanup passes */
                        nir_lower_load_const_to_scalar(nir[i]);
                        nir_move_options move_opts = (nir_move_options)(