1 files changed, 23 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index 623a8b711ed8..2e459c9a64d4 100644
--- a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -104,6 +104,21 @@ static bool mergeEmptyReturnBlocks(Function &F) {
       continue;
     }
 
+    // Skip merging if this would result in a CallBr instruction with a
+    // duplicate destination. FIXME: See note in CodeGenPrepare.cpp.
+    bool SkipCallBr = false;
+    for (pred_iterator PI = pred_begin(&BB), E = pred_end(&BB);
+         PI != E && !SkipCallBr; ++PI) {
+      if (auto *CBI = dyn_cast<CallBrInst>((*PI)->getTerminator()))
+        for (unsigned i = 0, e = CBI->getNumSuccessors(); i != e; ++i)
+          if (RetBlock == CBI->getSuccessor(i)) {
+            SkipCallBr = true;
+            break;
+          }
+    }
+    if (SkipCallBr)
+      continue;
+
     // Otherwise, we found a duplicate return block.  Merge the two.
     Changed = true;
 
@@ -266,6 +281,14 @@ struct CFGSimplifyPass : public FunctionPass {
       return false;
 
     Options.AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+    if (F.hasFnAttribute(Attribute::OptForFuzzing)) {
+      Options.setSimplifyCondBranch(false)
+             .setFoldTwoEntryPHINode(false);
+    } else {
+      Options.setSimplifyCondBranch(true)
+             .setFoldTwoEntryPHINode(true);
+    }
+
     auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
     return simplifyFunctionCFG(F, TTI, Options);
   }