[llvm] r356973 - X86Parser: Fix potential reference to deleted object

[Craig Topper via llvm-commits]

Author: ctopper
Date: Mon Mar 25 20:12:43 2019
New Revision: 356973

URL: http://llvm.org/viewvc/llvm-project?rev=356973&view=rev
Log:
X86Parser: Fix potential reference to deleted object

Within the MatchFPUWaitAlias function, Operands[0] is potentially overwritten leading to &Op referencing a deleted object. To fix this, assign the reference after the function.

Differential Revision: https://reviews.llvm.org/D57376

Modified:
    llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp

Modified: llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp?rev=356973&r1=356972&r2=356973&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp (original)
+++ llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp Mon Mar 25 20:12:43 2019
@@ -2949,13 +2949,13 @@ bool X86AsmParser::MatchAndEmitATTInstru
                                               uint64_t &ErrorInfo,
                                               bool MatchingInlineAsm) {
   assert(!Operands.empty() && "Unexpect empty operand list!");
-  X86Operand &Op = static_cast<X86Operand &>(*Operands[0]);
-  assert(Op.isToken() && "Leading operand should always be a mnemonic!");
+  assert((*Operands[0]).isToken() && "Leading operand should always be a mnemonic!");
   SMRange EmptyRange = None;
 
   // First, handle aliases that expand to multiple instructions.
-  MatchFPUWaitAlias(IDLoc, Op, Operands, Out, MatchingInlineAsm);
-
+  MatchFPUWaitAlias(IDLoc, static_cast<X86Operand &>(*Operands[0]), Operands,
+                    Out, MatchingInlineAsm);
+  X86Operand &Op = static_cast<X86Operand &>(*Operands[0]);
   bool WasOriginallyInvalidOperand = false;
   unsigned Prefixes = getPrefixes(Operands);
 
@@ -3132,15 +3132,15 @@ bool X86AsmParser::MatchAndEmitIntelInst
                                                 uint64_t &ErrorInfo,
                                                 bool MatchingInlineAsm) {
   assert(!Operands.empty() && "Unexpect empty operand list!");
-  X86Operand &Op = static_cast<X86Operand &>(*Operands[0]);
-  assert(Op.isToken() && "Leading operand should always be a mnemonic!");
-  StringRef Mnemonic = Op.getToken();
+  assert((*Operands[0]).isToken() && "Leading operand should always be a mnemonic!");
+  StringRef Mnemonic = (static_cast<X86Operand &>(*Operands[0])).getToken();
   SMRange EmptyRange = None;
-  StringRef Base = Op.getToken();
+  StringRef Base = (static_cast<X86Operand &>(*Operands[0])).getToken();
   unsigned Prefixes = getPrefixes(Operands);
 
   // First, handle aliases that expand to multiple instructions.
-  MatchFPUWaitAlias(IDLoc, Op, Operands, Out, MatchingInlineAsm);
+  MatchFPUWaitAlias(IDLoc, static_cast<X86Operand &>(*Operands[0]), Operands, Out, MatchingInlineAsm);
+  X86Operand &Op = static_cast<X86Operand &>(*Operands[0]);
 
   MCInst Inst;