[Mesa-dev] [PATCH 11/14] i965: Don't calculate masks of used FS inputs

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

This previously enabled some optimizations in the fragment shader
(interpolation, etc.) if some input components were always 0.0 or
1.0.  However, this data was generated by analyzing Mesa IR.  The
next patch in this series removes generation of Mesa IR for GLSL
paths.  When we detect that case, just set the used mask to ~0 and
circumvent the optimizations.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/mesa/drivers/dri/i965/brw_vs_constval.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_vs_constval.c b/src/mesa/drivers/dri/i965/brw_vs_constval.c
index 9ce5ab3..5b26c7a 100644
--- a/src/mesa/drivers/dri/i965/brw_vs_constval.c
+++ b/src/mesa/drivers/dri/i965/brw_vs_constval.c
@@ -195,6 +195,21 @@ static void calc_wm_input_sizes( struct brw_context *brw )
    GLuint insn;
    GLuint i;
 
+   /* Mesa IR is not generated for GLSL vertex shaders.  If there's no Mesa
+    * IR, the code below cannot determine which output components are
+    * written.  So, skip it and assume everything is written.  This
+    * circumvents some optimizations in the fragment shader, but it guarantees
+    * that correct code is generated.
+    */
+   if (vp->program.Base.NumInstructions == 0) {
+      brw->wm.input_size_masks[0] = ~0;
+      brw->wm.input_size_masks[1] = ~0;
+      brw->wm.input_size_masks[2] = ~0;
+      brw->wm.input_size_masks[3] = ~0;
+      return;
+   }
+
+
    memset(&t, 0, sizeof(t));
 
    /* _NEW_LIGHT | _NEW_PROGRAM */
-- 
1.7.6.4