Mesa (master): radeonsi: preload PS inputs only if KILL is used

[Marek Olšák]

Module: Mesa
Branch: master
Commit: 59c5da40ed2c6c56e29b562c2ee2c8705f28738b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=59c5da40ed2c6c56e29b562c2ee2c8705f28738b

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Thu Jan 19 13:58:50 2017 +0100

radeonsi: preload PS inputs only if KILL is used

so that most shaders can get lower VGPR usage thanks to lazy input loading.
I think this is a more accurate constraint that prevents the black transitions
in Witcher 2.

Affected shaders (7758):
Max Waves: 57437 -> 58231 (1.38 %)

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

---

 src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
index 8d19a4e..4f355e5 100644
--- a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
+++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
@@ -637,11 +637,15 @@ store_value_to_array(struct lp_build_tgsi_context *bld_base,
 
 /* If this is true, preload FS inputs at the beginning of shaders. Otherwise,
  * reload them at each use. This must be true if the shader is using
- * derivatives, because all inputs should be loaded in the WQM mode.
+ * derivatives and KILL, because KILL can leave the WQM and then a lazy
+ * input load isn't in the WQM anymore.
  */
 static bool si_preload_fs_inputs(struct si_shader_context *ctx)
 {
-	return ctx->shader->selector->info.uses_derivatives;
+	struct si_shader_selector *sel = ctx->shader->selector;
+
+	return sel->info.uses_derivatives &&
+	       sel->info.uses_kill;
 }
 
 static LLVMValueRef