From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Thu, 5 Sep 2019 10:18:24 +0000 (+0000)
Subject: [X86] X86InstrInfo::optimizeCompareInstr - fix potential null dereference.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a10e7d61af25c987a324dc61371e68a8f72ca3d3;p=llvm

[X86] X86InstrInfo::optimizeCompareInstr - fix potential null dereference.

Fixes clang static-analyzer warning.

Technically the MachineInstr *Sub might still be null if we're comparing zero (IsCmpZero == true), although this probably won't happen as SrcReg2 is probably == 0.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@371047 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index d597ec90ea6..bf7dcb232b8 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -3616,8 +3616,9 @@ bool X86InstrInfo::optimizeCompareInstr(MachineInstr &CmpInstr, unsigned SrcReg,
   if (!IsCmpZero && !Sub)
     return false;
 
-  bool IsSwapped = (SrcReg2 != 0 && Sub->getOperand(1).getReg() == SrcReg2 &&
-                    Sub->getOperand(2).getReg() == SrcReg);
+  bool IsSwapped =
+      (SrcReg2 != 0 && Sub && Sub->getOperand(1).getReg() == SrcReg2 &&
+       Sub->getOperand(2).getReg() == SrcReg);
 
   // Scan forward from the instruction after CmpInstr for uses of EFLAGS.
   // It is safe to remove CmpInstr if EFLAGS is redefined or killed.