From 736423af53d707e097a174c3a91b75132b8dc6b1 Mon Sep 17 00:00:00 2001
From: Jon Roelofs <jonathan_roelofs@apple.com>
Date: Mon, 27 Jul 2020 12:34:36 -0600
Subject: [PATCH] [OldPM] Print out a bit more when passes lie about changing
 IR

https://reviews.llvm.org/D84686
---
 llvm/lib/IR/LegacyPassManager.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/IR/LegacyPassManager.cpp b/llvm/lib/IR/LegacyPassManager.cpp
index c01696e..96434ae 100644
--- a/llvm/lib/IR/LegacyPassManager.cpp
+++ b/llvm/lib/IR/LegacyPassManager.cpp
@@ -1586,9 +1586,12 @@ bool FPPassManager::runOnFunction(Function &F) {
 #endif
       LocalChanged |= FP->runOnFunction(F);
 
-#ifdef EXPENSIVE_CHECKS
-      assert((LocalChanged || (RefHash == StructuralHash(F))) &&
-             "Pass modifies its input and doesn't report it.");
+#if defined(EXPENSIVE_CHECKS) && !defined(NDEBUG)
+      if (!LocalChanged && (RefHash != StructuralHash(F))) {
+        llvm::errs() << "Pass modifies its input and doesn't report it: "
+                     << FP->getPassName() << "\n";
+        assert(false && "Pass modifies its input and doesn't report it.");
+      }
 #endif
 
       if (EmitICRemark) {
-- 
2.7.4