[Mesa-dev] [PATCH 04/21] glsl: Use a single bit for the dual-source blend index

[Ian Romanick]

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

The only values allowed are 0 and 1, and the value is checked before
assigning.

With the previous changes, reduces the peak ir_variable memory usage in
a trimmed apitrace of dota2 by 204KiB on 64-bit.

Before: IR MEM: variable usage / name / total: 6374280 1439077 7813357
After:  IR MEM: variable usage / name / total: 6164976 1439077 7604053

Reduces the peak ir_variable memory usage in a trimmed apitrace of dota2
by 102KiB on 32-bit.

Before: IR MEM: variable usage / name / total: 4850844 915817 5766661
After:  IR MEM: variable usage / name / total: 4746192 915817 5662009

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/glsl/ir.h | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index 93d5aef..3767f2a 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -651,6 +651,15 @@ public:
       unsigned from_named_ifc_block_array:1;
 
       /**
+       * Output index for dual source blending.
+       *
+       * \note
+       * The GLSL spec only allows the values 0 or 1 for the index in \b dual
+       * source blending.
+       */
+      unsigned index:1;
+
+      /**
        * \brief Layout qualifier for gl_FragDepth.
        *
        * This is not equal to \c ir_depth_layout_none if and only if this
@@ -679,11 +688,6 @@ public:
       int location;
 
       /**
-       * output index for dual source blending.
-       */
-      int index;
-
-      /**
        * Initial binding point for a sampler, atomic, or UBO.
        *
        * For array types, this represents the binding point for the first element.
-- 
1.8.1.4