[llvm] [LoopFusion] Fix sink instructions (PR #147501)

[Madhur Amilkanthwar via llvm-commits]

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@@ -1176,9 +1176,31 @@ struct LoopFuser {
     return true;
   }
 
+  void fixPHINodes(SmallVector<Instruction *, 4> &SafeToSink,
+                   const FusionCandidate &FC0,
+                   const FusionCandidate &FC1) const {
+    // Iterate over SafeToSink instructions and update PHI nodes
+    // to take values from the latch block of FC0 if they are taking
+    // from the latch block of FC1.
+    for (Instruction *Inst : SafeToSink) {
+      LLVM_DEBUG(dbgs() << "UPDATING: Instruction: " << *Inst << "\n");
+      // Continue if the instruction is not a PHI node.
+      if (!isa<PHINode>(Inst))
+        continue;
+      PHINode *Phi = dyn_cast<PHINode>(Inst);
+      LLVM_DEBUG(dbgs() << "UPDATING: PHI node: " << *Phi << "\n");
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madhur13490 wrote:

They are different.

https://github.com/llvm/llvm-project/pull/147501