From c9a1aed7fefe627820bb92154361ede0568229fc Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Mon, 26 Dec 2011 20:54:14 +0000
Subject: [PATCH] Update the branch weight metadata when reversing the order of
 a branch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147280 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/SimplifyCFG.cpp          |  5 +---
 .../SimplifyCFG/preserve-branchweights.ll     | 26 +++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)
 create mode 100644 test/Transforms/SimplifyCFG/preserve-branchweights.ll

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 7835349771f..9604f5e4822 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1603,10 +1603,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI) {
       }
       
       PBI->setCondition(NewCond);
-      BasicBlock *OldTrue = PBI->getSuccessor(0);
-      BasicBlock *OldFalse = PBI->getSuccessor(1);
-      PBI->setSuccessor(0, OldFalse);
-      PBI->setSuccessor(1, OldTrue);
+      PBI->swapSuccessors();
     }
     
     // If we have a bonus inst, clone it into the predecessor block.
diff --git a/test/Transforms/SimplifyCFG/preserve-branchweights.ll b/test/Transforms/SimplifyCFG/preserve-branchweights.ll
new file mode 100644
index 00000000000..dab0d7cdf99
--- /dev/null
+++ b/test/Transforms/SimplifyCFG/preserve-branchweights.ll
@@ -0,0 +1,26 @@
+; RUN: opt -simplifycfg -S -o - < %s | FileCheck %s
+
+declare void @helper(i32)
+
+define void @test1(i1 %a, i1 %b) {
+; CHECK @test1
+entry:
+  br i1 %a, label %Y, label %X, !prof !0
+; CHECK: br i1 %or.cond, label %Z, label %Y, !prof !0
+
+X:
+  %c = or i1 %b, false
+  br i1 %c, label %Z, label %Y
+
+Y:
+  call void @helper(i32 0)
+  ret void
+
+Z:
+  call void @helper(i32 1)
+  ret void
+}
+
+!0 = metadata !{metadata !"branch_weights", i32 1, i32 2}
+
+; CHECK: !0 = metadata !{metadata !"branch_weights", i32 2, i32 1}
-- 
2.34.1