[llvm] 83659c7 - [SimplifyCFG] simplifySingleResume(): FoldReturnIntoUncondBranch() already knows how to preserve DomTree

[Roman Lebedev via llvm-commits]

Author: Roman Lebedev
Date: 2020-12-20T00:18:34+03:00
New Revision: 83659c707675f81680e355d98bd3600cd59a9278

URL: https://github.com/llvm/llvm-project/commit/83659c707675f81680e355d98bd3600cd59a9278
DIFF: https://github.com/llvm/llvm-project/commit/83659c707675f81680e355d98bd3600cd59a9278.diff

LOG: [SimplifyCFG] simplifySingleResume(): FoldReturnIntoUncondBranch() already knows how to preserve DomTree

... 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.

Added: 
    llvm/test/Transforms/SimplifyCFG/duplicate-ret-into-uncond-br.ll

Modified: 
    llvm/lib/Transforms/Utils/SimplifyCFG.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index fec2a678182a..5a70bca2e8d9 100644
--- 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
index 000000000000..a48a08486b33
--- /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
+}