The UBO push analysis pass incorrectly assumed that all values would fit
within a 32B chunk, and only recorded a bit for the 32B chunk containing
the starting offset.
For example, if a UBO contained the following, tightly packed:
vec4 a; // [0, 16)
float b; // [16, 20)
vec4 c; // [20, 36)
then, c would start at offset 20 / 32 = 0 and end at 36 / 32 = 1,
which means that we ought to record two 32B chunks in the bitfield.
Similarly, dvec4s would suffer from the same problem.
v2: Rewrite the accounting, my calculations were wrong.
Reviewed-by: Rafael Antognolli <rafael.antogno...@intel.com> [v1]
---
src/intel/compiler/brw_nir_analyze_ubo_ranges.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/intel/compiler/brw_nir_analyze_ubo_ranges.c
b/src/intel/compiler/brw_nir_analyze_ubo_ranges.c
index d58fe3dd2e3..31026ca65ba 100644
--- a/src/intel/compiler/brw_nir_analyze_ubo_ranges.c
+++ b/src/intel/compiler/brw_nir_analyze_ubo_ranges.c
@@ -141,10 +141,17 @@ analyze_ubos_block(struct ubo_analysis_state *state,
nir_block *block)
if (offset >= 64)
continue;
+ /* The value might span multiple 32-byte chunks. */
+ const int bytes = nir_intrinsic_dest_components(intrin) *
+ (nir_dest_bit_size(intrin->dest) / 8);
+ const int start = ROUND_DOWN_TO(offset_const->u32[0], 32);
+ const int end = ALIGN(offset_const->u32[0] + bytes, 32);
+ const int chunks = (end - start) / 32;
+
/* TODO: should we count uses in loops as higher benefit? */
struct ubo_block_info *info = get_block_info(state, block);
- info->offsets |= 1ull << offset;
+ info->offsets |= ((1ull << chunks) - 1) << offset;
info->uses[offset]++;
}
}
--
2.17.0
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