From: Sean Fertile <sfertile@ca.ibm.com>
Date: Tue, 12 Feb 2019 20:03:04 +0000 (+0000)
Subject: Fix undefined behaviour in PPCInstPrinter::printBranchOperand.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=638090e32fa4c18e1251e265e2b16d990ff96e28;p=llvm

Fix undefined behaviour in PPCInstPrinter::printBranchOperand.

Fix the undefined behaviour introduced by my previous patch r353865 (left
shifting a potentially negative value), which was caught by the bots that run
UBSan.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353874 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp b/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
index 49e73891bc3..77206494990 100644
--- a/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
+++ b/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
@@ -382,7 +382,7 @@ void PPCInstPrinter::printBranchOperand(const MCInst *MI, unsigned OpNo,
   // Branches can take an immediate operand.  This is used by the branch
   // selection pass to print .+8, an eight byte displacement from the PC.
   O << ".";
-  int32_t Imm = MI->getOperand(OpNo).getImm() << 2;
+  int32_t Imm = SignExtend32<32>((unsigned)MI->getOperand(OpNo).getImm() << 2);
   if (Imm >= 0)
     O << "+";
   O << Imm;