Mesa (master): ac/nir: split 8-bit SSBO stores on GFX6

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Module: Mesa
Branch: master
Commit: c6bf1597d1e8abf122371118b04a85ee0aa6b3d5
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=c6bf1597d1e8abf122371118b04a85ee0aa6b3d5

Author: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Date:   Wed Jan 29 14:38:55 2020 +0100

ac/nir: split 8-bit SSBO stores on GFX6

Due to possible alignment issues, make sure to split stores of
8-bit vectors.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4339>

---

 src/amd/llvm/ac_nir_to_llvm.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/amd/llvm/ac_nir_to_llvm.c b/src/amd/llvm/ac_nir_to_llvm.c
index be1c599fbb1..84067667ef4 100644
--- a/src/amd/llvm/ac_nir_to_llvm.c
+++ b/src/amd/llvm/ac_nir_to_llvm.c
@@ -1740,6 +1740,15 @@ static void visit_store_ssbo(struct ac_nir_context *ctx,
 			count = 1;
 			num_bytes = 2;
 		}
+
+		/* Due to alignment issues, split stores of 8-bit vectors. */
+		if (ctx->ac.chip_class == GFX6 &&
+                    elem_size_bytes == 1 && count > 1) {
+			writemask |= ((1u << (count - 1)) - 1u) << (start + 1);
+			count = 1;
+			num_bytes = 1;
+		}
+
 		data = extract_vector_range(&ctx->ac, base_data, start, count);
 
 		offset = LLVMBuildAdd(ctx->ac.builder, base_offset,