Mesa (staging/22.0): nir: Handle register sources in lower_phis_to_regs_block

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Module: Mesa
Branch: staging/22.0
Commit: 0392fcf3c43e260a71f92a9030a82a5175cfc9f4
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=0392fcf3c43e260a71f92a9030a82a5175cfc9f4

Author: Jason Ekstrand <jason.ekstrand at collabora.com>
Date:   Fri Apr 22 16:37:37 2022 -0500

nir: Handle register sources in lower_phis_to_regs_block

During certain control-flow manipulation passes, we go out-of-SSA
temporarily in certain areas of the code to make control-flow
manipulation easier.  This can result in registers being in phi sources
temporarily.  If two sub-passes run before we get a chance to do
clean-up, we can end up doing some out-of-SSA and then a bit more
out-of-SSA and trigger this case.  It's easy enough to handle.

Fixes: a620f66872c2 ("nir: Add a couple quick-and-dirty out-of-SSA helpers")
Fixes: 79a987ad2a1e ("nir/opt_if: also merge break statements with ones after the branch")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6370
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16111>
(cherry picked from commit 4a4d6cdc80bb4e153bf263d1fed919a5026cff2a)

---

 .pick_status.json               |  2 +-
 src/compiler/nir/nir_from_ssa.c | 14 ++++++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index d8c5793bdf3..3de34717359 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -836,7 +836,7 @@
         "description": "nir: Handle register sources in lower_phis_to_regs_block",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "because_sha": "a620f66872c27fa24a1ccdd1d0a6e563eefbaad6"
     },
     {
diff --git a/src/compiler/nir/nir_from_ssa.c b/src/compiler/nir/nir_from_ssa.c
index 707e670cc15..9ad45cb1a8c 100644
--- a/src/compiler/nir/nir_from_ssa.c
+++ b/src/compiler/nir/nir_from_ssa.c
@@ -1006,10 +1006,16 @@ nir_lower_phis_to_regs_block(nir_block *block)
       nir_ssa_def_rewrite_uses(&phi->dest.ssa, def);
 
       nir_foreach_phi_src(src, phi) {
-         assert(src->src.is_ssa);
-         _mesa_set_add(visited_blocks, src->src.ssa->parent_instr->block);
-         place_phi_read(&b, reg, src->src.ssa, src->pred, visited_blocks);
-         _mesa_set_clear(visited_blocks, NULL);
+         if (src->src.is_ssa) {
+            _mesa_set_add(visited_blocks, src->src.ssa->parent_instr->block);
+            place_phi_read(&b, reg, src->src.ssa, src->pred, visited_blocks);
+            _mesa_set_clear(visited_blocks, NULL);
+         } else {
+            b.cursor = nir_after_block_before_jump(src->pred);
+            nir_ssa_def *src_ssa =
+               nir_ssa_for_src(&b, src->src, phi->dest.ssa.num_components);
+            nir_store_reg(&b, reg, src_ssa, ~0);
+         }
       }
 
       nir_instr_remove(&phi->instr);