[TwoAddressInstruction] Track MadeChange when eliminating REG_SEQUENCE (#173535)

TejaX-Alaghari · c-rhodes · commit c4bec64591ef · 2026-01-13T10:18:55.000Z
When `eliminateRegSequence()` is called, the pass modifies the
`MachineFunction` but `MadeChange` was not being set to true.
This causes the pass to incorrectly return `PreservedAnalyses::all()`
even though changes were made.
diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1865,8 +1865,10 @@ bool TwoAddressInstructionImpl::run() {
 
       // Expand REG_SEQUENCE instructions. This will position mi at the first
       // expanded instruction.
-      if (mi->isRegSequence())
+      if (mi->isRegSequence()) {
         eliminateRegSequence(mi);
+        MadeChange = true;
+      }
 
       DistanceMap.insert(std::make_pair(&*mi, ++Dist));
 
