From: Duncan P. N. Exon Smith <dexonsmith@apple.com>
Date: Wed, 17 Aug 2016 03:15:29 +0000 (+0000)
Subject: CodeGen: Avoid dereferencing end() in ScalarExprEmitter::EmitOverflowCheckedBinOp
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1802c44dd4ae1f9abb99ba7746c9eccdc9ef59c8;p=clang

CodeGen: Avoid dereferencing end() in ScalarExprEmitter::EmitOverflowCheckedBinOp

Use BB.getNextNode(), which returns nullptr on end(), instead of
&*BB.getIterator(), which is UB on end().
CodeGenFunction::createBasicBlock expects nullptr in this case already.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@278898 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index 700b5374ad..ba7f49b750 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -2371,9 +2371,8 @@ Value *ScalarExprEmitter::EmitOverflowCheckedBinOp(const BinOpInfo &Ops) {
 
   // Branch in case of overflow.
   llvm::BasicBlock *initialBB = Builder.GetInsertBlock();
-  llvm::Function::iterator insertPt = initialBB->getIterator();
-  llvm::BasicBlock *continueBB = CGF.createBasicBlock("nooverflow", CGF.CurFn,
-                                                      &*std::next(insertPt));
+  llvm::BasicBlock *continueBB =
+      CGF.createBasicBlock("nooverflow", CGF.CurFn, initialBB->getNextNode());
   llvm::BasicBlock *overflowBB = CGF.createBasicBlock("overflow", CGF.CurFn);
 
   Builder.CreateCondBr(overflow, overflowBB, continueBB);