Mesa (staging/21.2): ir3/ra: Fix available bitset for live-through collect srcs

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Module: Mesa
Branch: staging/21.2
Commit: 106b5764aee2baa331140727229eff9530c4b98e
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=106b5764aee2baa331140727229eff9530c4b98e

Author: Connor Abbott <cwabbott0 at gmail.com>
Date:   Fri Jul 23 11:56:14 2021 +0200

ir3/ra: Fix available bitset for live-through collect srcs

When we mark live-through sources that are merged with the destination
as killed, we kept the bitsets in sync, but we forgot to keep them in
sync when unmarking them after allocating the destination. The result
was that "available" wasn't correct for any instruction afterwards. This
resulted in a bad register allocation with IR3_SHADER_DEBUG=spillall for
a dEQP-VK test.

While we're changing this, use ra_foreach_src().

Fixes: 0ffcb19b9d9 ("ir3: Rewrite register allocation")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12033>
(cherry picked from commit 70c22d38945223fbdef699c8af60f8be95b178c8)

---

 .pick_status.json          |  2 +-
 src/freedreno/ir3/ir3_ra.c | 33 +++++++++++++++++++--------------
 2 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index b420d4fb839..fa1929c482d 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -661,7 +661,7 @@
         "description": "ir3/ra: Fix available bitset for live-through collect srcs",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "0ffcb19b9d9fbe902224542047c389a661fbf816"
     },
diff --git a/src/freedreno/ir3/ir3_ra.c b/src/freedreno/ir3/ir3_ra.c
index 6463b62ed2a..60eab79971f 100644
--- a/src/freedreno/ir3/ir3_ra.c
+++ b/src/freedreno/ir3/ir3_ra.c
@@ -548,6 +548,18 @@ ra_file_mark_killed(struct ra_file *file, struct ra_interval *interval)
    interval->is_killed = true;
 }
 
+static void
+ra_file_unmark_killed(struct ra_file *file, struct ra_interval *interval)
+{
+   assert(!interval->interval.parent);
+
+   for (physreg_t i = interval->physreg_start; i < interval->physreg_end; i++) {
+      BITSET_CLEAR(file->available, i);
+   }
+
+   interval->is_killed = false;
+}
+
 static physreg_t
 ra_interval_get_physreg(const struct ra_interval *interval)
 {
@@ -1311,15 +1323,11 @@ handle_collect(struct ra_ctx *ctx, struct ir3_instruction *instr)
     */
    physreg_t dst_fixed = (physreg_t)~0u;
 
-   for (unsigned i = 0; i < instr->srcs_count; i++) {
-      if (!ra_reg_is_src(instr->srcs[i]))
-         continue;
-
-      if (instr->srcs[i]->flags & IR3_REG_FIRST_KILL) {
-         mark_src_killed(ctx, instr->srcs[i]);
+   ra_foreach_src (src, instr) {
+      if (src->flags & IR3_REG_FIRST_KILL) {
+         mark_src_killed(ctx, src);
       }
 
-      struct ir3_register *src = instr->srcs[i];
       struct ra_interval *interval = &ctx->intervals[src->def->name];
 
       if (src->def->merge_set != dst_set || interval->is_killed)
@@ -1347,11 +1355,7 @@ handle_collect(struct ra_ctx *ctx, struct ir3_instruction *instr)
       allocate_dst(ctx, instr->dsts[0]);
 
    /* Remove the temporary is_killed we added */
-   for (unsigned i = 0; i < instr->srcs_count; i++) {
-      if (!ra_reg_is_src(instr->srcs[i]))
-         continue;
-
-      struct ir3_register *src = instr->srcs[i];
+   ra_foreach_src (src, instr) {
       struct ra_interval *interval = &ctx->intervals[src->def->name];
       while (interval->interval.parent != NULL) {
          interval = ir3_reg_interval_to_ra_interval(interval->interval.parent);
@@ -1359,8 +1363,9 @@ handle_collect(struct ra_ctx *ctx, struct ir3_instruction *instr)
 
       /* Filter out cases where it actually should be killed */
       if (interval != &ctx->intervals[src->def->name] ||
-          !(src->flags & IR3_REG_KILL))
-         interval->is_killed = false;
+          !(src->flags & IR3_REG_KILL)) {
+         ra_file_unmark_killed(ra_get_file(ctx, src), interval);
+      }
    }
 
    ra_foreach_src_rev (src, instr) {