Mesa (staging/20.1): spirv: Skip phis in unreachable blocks in the second phi pass

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Module: Mesa
Branch: staging/20.1
Commit: 8f9e4f9f62697be038dd98402626c4f457fd0316
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=8f9e4f9f62697be038dd98402626c4f457fd0316

Author: Jason Ekstrand <jason at jlekstrand.net>
Date:   Fri Jul 10 16:09:27 2020 -0500

spirv: Skip phis in unreachable blocks in the second phi pass

Closes: #3253
Fixes: 22fdb2f8551 "nir/spirv: Update to the latest revision"
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5855>
(cherry picked from commit 81773b4b441fbd8ec284de78e4dfdcecdca112dc)

---

 .pick_status.json            | 2 +-
 src/compiler/spirv/vtn_cfg.c | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 562d84ddf53..023b4a11808 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -625,7 +625,7 @@
         "description": "spirv: Skip phis in unreachable blocks in the second phi pass",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": "22fdb2f8551330fea308ce9cfe151ec00201e2b1"
     },
diff --git a/src/compiler/spirv/vtn_cfg.c b/src/compiler/spirv/vtn_cfg.c
index 395a5775606..a31047b18b1 100644
--- a/src/compiler/spirv/vtn_cfg.c
+++ b/src/compiler/spirv/vtn_cfg.c
@@ -1003,7 +1003,14 @@ vtn_handle_phi_second_pass(struct vtn_builder *b, SpvOp opcode,
       return true;
 
    struct hash_entry *phi_entry = _mesa_hash_table_search(b->phi_table, w);
-   vtn_assert(phi_entry);
+
+   /* It's possible that this phi is in an unreachable block in which case it
+    * may never have been emitted and therefore may not be in the hash table.
+    * In this case, there's no var for it and it's safe to just bail.
+    */
+   if (phi_entry == NULL)
+      return true;
+
    nir_variable *phi_var = phi_entry->data;
 
    for (unsigned i = 3; i < count; i += 2) {