On Wed, Aug 13, 2014 at 10:07 AM, <ville.syrj...@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrj...@linux.intel.com>
>
> 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;
> }
>
> This was tested on a PNV.
>
> Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> ---
> src/mesa/drivers/dri/i915/i915_context.h | 14 ++---
> src/mesa/drivers/dri/i915/i915_fragprog.c | 86
> +++++++++++++++++++++++++------
> 2 files changed, 74 insertions(+), 26 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i915/i915_context.h
> b/src/mesa/drivers/dri/i915/i915_context.h
> index 34af202..2615bd6 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;
I see idr committed this. Coverity is warning about "p->wpos_tex !=
-1" always being true, but I'm not sure why it wouldn't have
recognized that before -- wpos_tex was still unsigned.
It dates back to commit fceda4342cad.
Not sure if it's worth fixing.
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