glsl: Create a field to store fractional varying locations.

Currently, the location of each varying is recorded in ir_variable as
a multiple of the size of a vec4.  In order to pack varyings, we need
to be able to record, e.g. that a vec2 is stored in the second half of
a varying slot rather than the first half.

This patch introduces a field ir_variable::location_frac, which
represents the offset within a vec4 where a varying's value is stored.
Varyings that are not subject to packing will always have a
location_frac value of zero.

Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index e2ecb3d9dfd..85fc5ce95da 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -446,6 +446,15 @@ public:
    unsigned is_unmatched_generic_inout:1;
 
    /**
+    * If non-zero, then this variable may be packed along with other variables
+    * into a single varying slot, so this offset should be applied when
+    * accessing components.  For example, an offset of 1 means that the x
+    * component of this variable is actually stored in component y of the
+    * location specified by \c location.
+    */
+   unsigned location_frac:2;
+
+   /**
     * \brief Layout qualifier for gl_FragDepth.
     *
     * This is not equal to \c ir_depth_layout_none if and only if this