From 453683bf44f2112719802eaac2b332d49eebd640 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Mon, 19 Aug 2024 15:03:56 -0700
Subject: Tuple swizzling, concat, comparison and `countof`. (#4856)

* Tuple swizzling and element access.

* Update proposal status.

* Cleanup.

* Fix merrge error.

* Address review.
---
 source/slang/slang-ir-redundancy-removal.cpp | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

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

diff --git a/source/slang/slang-ir-redundancy-removal.cpp b/source/slang/slang-ir-redundancy-removal.cpp
index b679d8438..fa3cd444a 100644
--- a/source/slang/slang-ir-redundancy-removal.cpp
+++ b/source/slang/slang-ir-redundancy-removal.cpp
@@ -8,6 +8,19 @@ namespace Slang
 struct RedundancyRemovalContext
 {
     RefPtr<IRDominatorTree> dom;
+    bool isSingleIterationLoop(IRLoop* loop)
+    {
+        int useCount = 0;
+        for (auto use = loop->getBreakBlock()->firstUse; use; use = use->nextUse)
+        {
+            if (use->getUser() == loop)
+                continue;
+            useCount++;
+            if (useCount > 1)
+                return false;
+        }
+        return true;
+    }
 
     bool tryHoistInstToOuterMostLoop(IRGlobalValueWithCode* func, IRInst* inst)
     {
@@ -17,7 +30,8 @@ struct RedundancyRemovalContext
              parentBlock = dom->getImmediateDominator(parentBlock))
         {
             auto terminatorInst = parentBlock->getTerminator();
-            if (terminatorInst->getOp() == kIROp_loop)
+            if (terminatorInst->getOp() == kIROp_loop &&
+                !isSingleIterationLoop(as<IRLoop>(terminatorInst)))
             {
                 // Consider hoisting the inst into this block.
                 // This is only possible if all operands of the inst are dominating `parentBlock`.
-- 
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