Mesa (main): tgsi: Extend array lengths when merging usage_masks.

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Module: Mesa
Branch: main
Commit: 337b3dabc0ee1b31343e76a316f4d0443552650d
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=337b3dabc0ee1b31343e76a316f4d0443552650d

Author: Emma Anholt <emma at anholt.net>
Date:   Tue Apr 19 16:21:02 2022 -0700

tgsi: Extend array lengths when merging usage_masks.

With nir-to-tgsi, virgl saw a case where a previous declaration of array
.x and scalar .y (turning into an array with .xy) ended up being a
declaration of scalar .x and array .y (turning into a scalar with .xy).
Make sure we extend the declared array length as well.

One might think that the fix would be to union the .first/.last between
the two declarations being merged, but note that ureg_DECL_output() passes
in the current nr_output_regs as the index, so the .last would end up
getting extended for those callers (such as nir_to_tgsi fs outputs) every
time you merged.

Reviewed-by: Gert Wollny <gert.wollny at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13295>

---

 src/gallium/auxiliary/tgsi/tgsi_ureg.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/gallium/auxiliary/tgsi/tgsi_ureg.c b/src/gallium/auxiliary/tgsi/tgsi_ureg.c
index 76c1bd9f47f..398d59b957b 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_ureg.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_ureg.c
@@ -308,6 +308,8 @@ ureg_DECL_fs_input_centroid_layout(struct ureg_program *ureg,
          assert(ureg->input[i].interp_location == interp_location);
          if (ureg->input[i].array_id == array_id) {
             ureg->input[i].usage_mask |= usage_mask;
+            ureg->input[i].last = MAX2(ureg->input[i].last, ureg->input[i].first + array_size - 1);
+            ureg->nr_input_regs = MAX2(ureg->nr_input_regs, ureg->input[i].last + 1);
             goto out;
          }
          assert((ureg->input[i].usage_mask & usage_mask) == 0);
@@ -445,6 +447,8 @@ ureg_DECL_output_layout(struct ureg_program *ureg,
           ureg->output[i].semantic_index == semantic_index) {
          if (ureg->output[i].array_id == array_id) {
             ureg->output[i].usage_mask |= usage_mask;
+            ureg->output[i].last = MAX2(ureg->output[i].last, ureg->output[i].first + array_size - 1);
+            ureg->nr_output_regs = MAX2(ureg->nr_output_regs, ureg->output[i].last + 1);
             goto out;
          }
          assert((ureg->output[i].usage_mask & usage_mask) == 0);