[SimplifyCFG] simplifySingleResume(): FoldReturnIntoUncondBranch() already knows...

... so just ensure that we pass DomTreeUpdater it into it.

Apparently, there were no dedicated tests just for that functionality,
so i'm adding one here.

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index fec2a67..5a70bca 100644 (file)
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -4424,7 +4424,7 @@ bool SimplifyCFGOpt::simplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) {
       BasicBlock *Pred = UncondBranchPreds.pop_back_val();
       LLVM_DEBUG(dbgs() << "FOLDING: " << *BB
                         << "INTO UNCOND BRANCH PRED: " << *Pred);
-      (void)FoldReturnIntoUncondBranch(RI, BB, Pred);
+      (void)FoldReturnIntoUncondBranch(RI, BB, Pred, DTU);
     }
 
     // If we eliminated all predecessors of the block, delete the block now.
@@ -4432,7 +4432,10 @@ bool SimplifyCFGOpt::simplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) {
       // We know there are no successors, so just nuke the block.
       if (LoopHeaders)
         LoopHeaders->erase(BB);
-      BB->eraseFromParent();
+      if (DTU)
+        DTU->deleteBB(BB);
+      else
+        BB->eraseFromParent();
     }
 
     return true;

diff --git a/llvm/test/Transforms/SimplifyCFG/duplicate-ret-into-uncond-br.ll b/llvm/test/Transforms/SimplifyCFG/duplicate-ret-into-uncond-br.ll
new file mode 100644 (file)
index 0000000..a48a084
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/duplicate-ret-into-uncond-br.ll
@@ -0,0 +1,31 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -simplifycfg-dup-ret -S | FileCheck %s
+
+declare void @bar()
+declare void @baz()
+
+define void @foo(i1 %c) {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C:%.*]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK:       true:
+; CHECK-NEXT:    call void @bar()
+; CHECK-NEXT:    ret void
+; CHECK:       false:
+; CHECK-NEXT:    call void @baz()
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 %c, label %true, label %false
+
+true:
+  call void @bar()
+  br label %end
+
+false:
+  call void @baz()
+  br label %end
+
+end:
+  ret void
+}