[Mesa-dev] [PATCH] radv: enable lowering of fpow to fexp2 and flog2

[Samuel Pitoiset]

There is no fpow in hardware, so it's always lowered somewhere,
but it appears that lowering at NIR level is better. Figured while
comparing compute shaders between RadeonSI and RADV.

Polaris10:
Totals from affected shaders:
SGPRS: 18936 -> 18904 (-0.17 %)
VGPRS: 12240 -> 12220 (-0.16 %)
Spilled SGPRs: 2809 -> 2809 (0.00 %)
Code Size: 718116 -> 719848 (0.24 %) bytes
Max Waves: 1409 -> 1410 (0.07 %)

Vega10:
Totals from affected shaders:
SGPRS: 18392 -> 18392 (0.00 %)
VGPRS: 12008 -> 11920 (-0.73 %)
Spilled SGPRs: 3001 -> 2981 (-0.67 %)
Code Size: 777444 -> 778788 (0.17 %) bytes
Max Waves: 1503 -> 1504 (0.07 %)

Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
---
 src/amd/vulkan/radv_shader.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/amd/vulkan/radv_shader.c b/src/amd/vulkan/radv_shader.c
index af094e6220..769e991f93 100644
--- a/src/amd/vulkan/radv_shader.c
+++ b/src/amd/vulkan/radv_shader.c
@@ -67,6 +67,7 @@ static const struct nir_shader_compiler_options nir_options = {
 	.lower_extract_byte = true,
 	.lower_extract_word = true,
 	.lower_ffma = true,
+	.lower_fpow = true,
 	.vs_inputs_dual_locations = true,
 	.max_unroll_iterations = 32
 };
-- 
2.16.1