From 9476d4543f4336a66308e55f722b0b0b2bd69dd2 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Thu, 16 Mar 2023 23:46:14 -0700
Subject: Fix Phi simplification bug. (#2710)

* Fix Phi simplification bug.

* Fix up.

* Fix.

* Fix.

* Fix.

* Fix.

* Fix.

* Fix test.

* Fix test.

---------

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/slang-ir-dominators.cpp | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'source/slang/slang-ir-dominators.cpp')

diff --git a/source/slang/slang-ir-dominators.cpp b/source/slang/slang-ir-dominators.cpp
index 5f606092b..e03ae9425 100644
--- a/source/slang/slang-ir-dominators.cpp
+++ b/source/slang/slang-ir-dominators.cpp
@@ -616,6 +616,9 @@ struct DominatorTreeComputationContext
 
     RefPtr<IRDominatorTree> createDominatorTree(IRGlobalValueWithCode* code)
     {
+        if (code->getFirstBlock() == nullptr)
+            return nullptr;
+
         // We first run the Cooper et al. algorithm to compute the `doms` array
         // which encodes immediate dominators.
         //
-- 
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