From 0ba457138d181f0e9f6770e4750184d3eb8697a5 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo@fhahn.com>
Date: Fri, 23 May 2025 13:48:00 +0100
Subject: [PATCH] [Local] Verify opcodes match for all insts passed to
 mergeFlags (NFC).

---
 llvm/include/llvm/Transforms/Utils/Local.h | 6 ++++++
 llvm/lib/Transforms/Utils/Local.cpp        | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/llvm/include/llvm/Transforms/Utils/Local.h b/llvm/include/llvm/Transforms/Utils/Local.h
index 9214aad4e6aec..6162557496405 100644
--- a/llvm/include/llvm/Transforms/Utils/Local.h
+++ b/llvm/include/llvm/Transforms/Utils/Local.h
@@ -565,6 +565,12 @@ struct OverflowTracking {
   bool HasNSW = true;
   bool IsDisjoint = true;
 
+#ifndef NDEBUG
+  /// Opcode of merged instructions. All instructions passed to mergeFlags must
+  /// have the same opcode.
+  std::optional<unsigned> Opcode;
+#endif
+
   // Note: At the moment, users are responsible to manage AllKnownNonNegative
   // and AllKnownNonZero manually. AllKnownNonNegative can be true in a case
   // where one of the operands is negative, but one the operators is not NSW.
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 69dcd30d1af99..fe1391a501b43 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -4364,6 +4364,13 @@ bool llvm::inferAttributesFromOthers(Function &F) {
 }
 
 void OverflowTracking::mergeFlags(Instruction &I) {
+#ifndef NDEBUG
+  if (Opcode)
+    assert(Opcode == I.getOpcode() &&
+           "can only use mergeFlags on instructions with matching opcodes");
+  else
+    Opcode = I.getOpcode();
+#endif
   if (isa<OverflowingBinaryOperator>(&I)) {
     HasNUW &= I.hasNoUnsignedWrap();
     HasNSW &= I.hasNoSignedWrap();