Mesa (master): llvmpipe: only read 0 for channels being read

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Module: Mesa
Branch: master
Commit: 430e3310e2aed924dc4e0729644e629007d73ef7
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=430e3310e2aed924dc4e0729644e629007d73ef7

Author: Dave Airlie <airlied at redhat.com>
Date:   Wed Aug 12 15:48:42 2020 +1000

llvmpipe: only read 0 for channels being read

KHR-GL45.robust_buffer_access_behavior.vertex_buffer_objects
on the CTS 4.6.0 branch and this fixes it.

Roland identified that if the vertex format doesn't contain channels
then we shouldn't be overriding them to 0, so RGB fetch out of bounds
should return 0 for RGB, but the A channel should still be getting back
1.

Cc: <mesa-stable at lists.freedesktop.org>
Reviewed-by: Roland Scheidegger <sroland at vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6287>

---

 src/gallium/auxiliary/draw/draw_llvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gallium/auxiliary/draw/draw_llvm.c b/src/gallium/auxiliary/draw/draw_llvm.c
index 845ed6242b1..22644aa5eab 100644
--- a/src/gallium/auxiliary/draw/draw_llvm.c
+++ b/src/gallium/auxiliary/draw/draw_llvm.c
@@ -1128,7 +1128,7 @@ fetch_vector(struct gallivm_state *gallivm,
    }
 
    /* out-of-bound fetches return all zeros */
-   for (i = 0; i < TGSI_NUM_CHANNELS; i++) {
+   for (i = 0; i < format_desc->nr_channels; i++) {
       inputs[i] = LLVMBuildBitCast(builder, inputs[i], blduivec.vec_type, "");
       inputs[i] = LLVMBuildAnd(builder, inputs[i], valid_mask, "");
       inputs[i] = LLVMBuildBitCast(builder, inputs[i],