The pattern of calling opt algebraic first seems to have originated in i965. The order in OpenGL drivers generally doesn't matter because the GLSL IR optimisations do constant folding before opt algebraic.
However in Vulkan drivers calling opt algebraic first can result in missed constant folding opportunities. vkpipeline-db results (VEGA64): Totals from affected shaders: SGPRS: 3160 -> 3176 (0.51 %) VGPRS: 3588 -> 3580 (-0.22 %) Spilled SGPRs: 52 -> 44 (-15.38 %) Spilled VGPRs: 0 -> 0 (0.00 %) Private memory VGPRs: 0 -> 0 (0.00 %) Scratch size: 12 -> 12 (0.00 %) dwords per thread Code Size: 261812 -> 261036 (-0.30 %) bytes LDS: 7 -> 7 (0.00 %) blocks Max Waves: 346 -> 348 (0.58 %) Wait states: 0 -> 0 (0.00 %) --- src/amd/vulkan/radv_shader.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/amd/vulkan/radv_shader.c b/src/amd/vulkan/radv_shader.c index cd5a9f2afb4..ad7b2439735 100644 --- a/src/amd/vulkan/radv_shader.c +++ b/src/amd/vulkan/radv_shader.c @@ -162,8 +162,8 @@ radv_optimize_nir(struct nir_shader *shader, bool optimize_conservatively, NIR_PASS(progress, shader, nir_opt_dead_cf); NIR_PASS(progress, shader, nir_opt_cse); NIR_PASS(progress, shader, nir_opt_peephole_select, 8, true, true); - NIR_PASS(progress, shader, nir_opt_algebraic); NIR_PASS(progress, shader, nir_opt_constant_folding); + NIR_PASS(progress, shader, nir_opt_algebraic); NIR_PASS(progress, shader, nir_opt_undef); NIR_PASS(progress, shader, nir_opt_conditional_discard); if (shader->options->max_unroll_iterations) { -- 2.20.1 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev