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ir3: Align TCS per-patch output to 64 bytes to prevent stale reads

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Empirically, TCS outputs have to be aligned to 64 bytes,
otherwise stale data may be read in rare cases. The exact
reason is not clear, but tests and proprietary driver behavior
strongly point at the need for 64 byte alignment.

Fixes tesselation issues in at least "Conan Exiles" but likely in many
more cases.

CC: mesa-stable

Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39890>
This commit is contained in:
Danylo Piliaiev 2026-02-12 19:56:35 +01:00 • committed by Marge Bot
parent e111422f7f
commit 47251b2e2d
1 changed files with 7 additions and 1 deletions
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8
src/freedreno/ir3/ir3_nir_lower_tess.c
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@ -662,7 +662,13 @@ ir3_nir_lower_tess_ctrl(nir_shader *shader, struct ir3_shader_variant *v,
build_primitive_map(shader, &state.map);
memcpy(v->output_loc, state.map.loc, sizeof(v->output_loc));
v->output_size = state.map.stride;
/* Empirically, TCS outputs have to be aligned to 64 bytes,
* otherwise stale data may be read in rare cases. The exact
* reason is not clear, but tests and proprietary driver behavior
* strongly point at the need for 64 byte alignment.
*/
v->output_size = ALIGN_POT(state.map.stride, 16);
nir_function_impl *impl = nir_shader_get_entrypoint(shader);
assert(impl);