[Mesa-dev] [PATCH] llvmpipe: Tighten check for alpha-only formats

[Richard Sandiford]

The AoS version of ld_build_blend_factor was assuming that if the first
channel was alpha, there were no rgb components.

Fixes several piglit tests on System z.  No piglit regressions on x86_64.
The shortcut is still used in tests like spec/ARB_framebuffer_object/
fbo-alpha.

Signed-off-by: Richard Sandiford <rsandifo at linux.vnet.ibm.com>
---
 src/gallium/drivers/llvmpipe/lp_bld_blend_aos.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gallium/drivers/llvmpipe/lp_bld_blend_aos.c b/src/gallium/drivers/llvmpipe/lp_bld_blend_aos.c
index c4d04a2..7c485e7 100644
--- a/src/gallium/drivers/llvmpipe/lp_bld_blend_aos.c
+++ b/src/gallium/drivers/llvmpipe/lp_bld_blend_aos.c
@@ -245,7 +245,7 @@ lp_build_blend_factor(struct lp_build_blend_aos_context *bld,
    LLVMValueRef rgb_factor_, alpha_factor_;
    enum lp_build_blend_swizzle rgb_swizzle;
 
-   if (alpha_swizzle == 0) {
+   if (alpha_swizzle == UTIL_FORMAT_SWIZZLE_X && num_channels == 1) {
       return lp_build_blend_factor_unswizzled(bld, alpha_factor, TRUE);
    }
 
-- 
1.7.11.7