i915: Fix texcoord vs. varying collision in fragment programs

i915 fragment programs utilize the texture coordinate registers
for both texture coordinates and varyings. Unfortunately the
code doesn't check if the same index might be in use for both.
It just naively uses the index to pick a texture unit, which
could lead to collisions.

Add an extra mapping step to allocate non conflicting texture
units for both uses.

The issue can be reproduced with a pair of simple shaders like
these:
 attribute vec4 in_mod;
 varying vec4 mod;
 void main() {
   mod = in_mod;
   gl_TexCoord[0] = gl_MultiTexCoord0;
   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
 }

 varying vec4 mod;
 uniform sampler2D tex;
 void main() {
   gl_FragColor = texture2D(tex, vec2(gl_TexCoord[0])) * mod;
 }

Fixes many piglit tests on i915:

    glsl-link-varyings-2
    glsl-orangebook-ch06-bump
    interpolation-none-gl_frontcolor-smooth-fixed
    interpolation-none-gl_frontcolor-smooth-none
    interpolation-none-gl_frontcolor-smooth-vertex
    interpolation-none-gl_frontsecondarycolor-smooth-fixed
    interpolation-none-gl_frontsecondarycolor-smooth-vertex
    interpolation-none-gl_frontsecondarycolor-smooth-none
    interpolation-none-other-flat-fixed
    interpolation-none-other-flat-none
    interpolation-none-other-flat-vertex
    interpolation-none-other-smooth-fixed
    interpolation-none-other-smooth-none
    interpolation-none-other-smooth-vertex

v2 [idr]: Minor formatting tweaks.

Signed-off-by: Ville Syrjälä <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
Cc: "11.0" <[email protected]>

1 files changed, 4 insertions, 10 deletions

diff --git a/src/mesa/drivers/dri/i915/i915_context.h b/src/mesa/drivers/dri/i915/i915_context.h
index fa58ecb8165..d8f592bcb9f 100644
--- a/src/mesa/drivers/dri/i915/i915_context.h
+++ b/src/mesa/drivers/dri/i915/i915_context.h
@@ -115,6 +115,8 @@ enum {
    I915_RASTER_RULES_SETUP_SIZE,
 };
 
+#define I915_TEX_UNITS 8
+
 #define I915_MAX_CONSTANT      32
 #define I915_CONSTANT_SIZE     (2+(4*I915_MAX_CONSTANT))
 
@@ -194,7 +196,8 @@ struct i915_fragment_program
 
    /* Helpers for i915_fragprog.c:
     */
-   GLuint wpos_tex;
+   uint8_t texcoord_mapping[I915_TEX_UNITS];
+   uint8_t wpos_tex;
    bool depth_written;
 
    struct
@@ -205,15 +208,6 @@ struct i915_fragment_program
    GLuint nr_params;
 };
 
-
-
-
-
-
-
-#define I915_TEX_UNITS 8
-
-
 struct i915_hw_state
 {
    GLuint Ctx[I915_CTX_SETUP_SIZE];