Module: Mesa
Branch: main
Commit: 67e6ca1924e2cba6f8b72483be3854cd40fa13d7
URL:
http://cgit.freedesktop.org/mesa/mesa/commit/?id=67e6ca1924e2cba6f8b72483be3854cd40fa13d7
Author: Faith Ekstrand <faith.ekstr...@collabora.com>
Date: Mon Nov 27 21:13:48 2023 -0600
nak/nir: Handle CBuf alignment rules
The NIR lowering is more complete and lets us properly handle 16-bit
loads which, weirdly, require a 4B alignment.
Fixes: bda208665f99 ("nak: Handle non-DW-aligned UBO loads")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26412>
---
src/nouveau/compiler/nak_nir.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/src/nouveau/compiler/nak_nir.c b/src/nouveau/compiler/nak_nir.c
index 034c2f92916..d3551571e84 100644
--- a/src/nouveau/compiler/nak_nir.c
+++ b/src/nouveau/compiler/nak_nir.c
@@ -989,7 +989,28 @@ nak_mem_access_size_align(nir_intrinsic_op intrin,
if (intrin == nir_intrinsic_load_ubo)
chunk_bytes = MIN2(chunk_bytes, 8);
- if (chunk_bytes < 4) {
+ if (intrin == nir_intrinsic_load_ubo && align < 4) {
+ /* CBufs require 4B alignment unless we're doing a ldc.u8 or ldc.i8.
+ * In particular, this applies to ldc.u16 which means we either have to
+ * fall back to two ldc.u8 or use ldc.u32 and shift stuff around to get
+ * the 16bit value out. Fortunately, nir_lower_mem_access_bit_sizes()
+ * can handle over-alignment for reads.
+ */
+ if (align == 2 || offset_is_const) {
+ return (nir_mem_access_size_align) {
+ .bit_size = 32,
+ .num_components = 1,
+ .align = 4,
+ };
+ } else {
+ assert(align == 1);
+ return (nir_mem_access_size_align) {
+ .bit_size = 8,
+ .num_components = 1,
+ .align = 1,
+ };
+ }
+ } else if (chunk_bytes < 4) {
return (nir_mem_access_size_align) {
.bit_size = chunk_bytes * 8,
.num_components = 1,
