Mesa (staging/20.1): freedreno/ir3: Fix register allocation assertion failures.

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Module: Mesa
Branch: staging/20.1
Commit: 3bcb1c50e13213231c5d26bd82f7ad8a7c0bb732
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=3bcb1c50e13213231c5d26bd82f7ad8a7c0bb732

Author: Eric Anholt <eric at anholt.net>
Date:   Tue Apr 21 13:26:14 2020 -0700

freedreno/ir3: Fix register allocation assertion failures.

We were failing to tell the allocator about the restriction that scalar
texture instructions (allocated as scalar regs) couldn't be allocated such
that the start of the full unwritemasked vector started before r0.  There
was a patch in select_reg_callback on a6xx that tried to work around that,
but you could still end up backed into a corner you shouldn't be because
we didn't tell the RA what it needed.

Fixes compiler assertion failures on a300-a400's blit_z shader, used for
Z32F gmem blits.

Looks like as a result we get tighter register allocation but more nops:

instructions in affected programs: 757945 -> 760356 (0.32%)
nops in affected programs: 317983 -> 320468 (0.78%)
non-nops in affected programs: 27525 -> 27451 (-0.27%)
mov in affected programs: 3098 -> 3023 (-2.42%)
dwords in affected programs: 109664 -> 110656 (0.90%)
last-baryf in affected programs: 112701 -> 112847 (0.13%)
full in affected programs: 4326 -> 4011 (-7.28%)
sstall in affected programs: 120550 -> 120836 (0.24%)
(ss) in affected programs: 13939 -> 13918 (-0.15%)
(sy) in affected programs: 3006 -> 2786 (-7.32%)

(cherry picked from commit b420d04e1f744d15622f89180d1e3e511d92a8ba)

Signed-off-by: Rob Clark <robdclark at chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5612>

---

 .pick_status.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.pick_status.json b/.pick_status.json
index 090f3fb2e63..ef557653c56 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -18517,7 +18517,7 @@
         "description": "freedreno/ir3: Fix register allocation assertion failures.",
         "nominated": false,
         "nomination_type": null,
-        "resolution": 4,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": null
     },