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X86: Avoid accessing SDValues after they've been RAUW'd

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This fixes two use-after-frees in selectLEA64_32Addr. If matchAddress
matches an ADD with an AND as an operand, and that AND hits one of the
"heroic transforms" that folds masks and shifts, we end up with N
pointing to an SDNode that was deleted. Make sure we're done accessing
it before that.

Found by ASan with the recycling allocator changes in llvm.org/PR26808.

llvm-svn: 266130
This commit is contained in:
Justin Bogner 2016-04-12 21:34:24 +00:00
parent 1b80834fc9
commit 7ca5d7c5c4
1 changed files with 8 additions and 3 deletions
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11
lib/Target/X86/X86ISelDAGToDAG.cpp
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@ -1574,10 +1574,12 @@ bool X86DAGToDAGISel::selectMOV64Imm32(SDValue N, SDValue &Imm) {
bool X86DAGToDAGISel::selectLEA64_32Addr(SDValue N, SDValue &Base,
SDValue &Scale, SDValue &Index,
SDValue &Disp, SDValue &Segment) {
// Save the debug loc before calling selectLEAAddr, in case it invalidates N.
SDLoc DL(N);
if (!selectLEAAddr(N, Base, Scale, Index, Disp, Segment))
return false;
SDLoc DL(N);
RegisterSDNode *RN = dyn_cast<RegisterSDNode>(Base);
if (RN && RN->getReg() == 0)
Base = CurDAG->getRegister(0, MVT::i64);
@ -1617,6 +1619,10 @@ bool X86DAGToDAGISel::selectLEAAddr(SDValue N,
SDValue &Segment) {
X86ISelAddressMode AM;
// Save the DL and VT before calling matchAddress, it can invalidate N.
SDLoc DL(N);
MVT VT = N.getSimpleValueType();
// Set AM.Segment to prevent MatchAddress from using one. LEA doesn't support
// segments.
SDValue Copy = AM.Segment;
@ -1627,7 +1633,6 @@ bool X86DAGToDAGISel::selectLEAAddr(SDValue N,
assert (T == AM.Segment);
AM.Segment = Copy;
MVT VT = N.getSimpleValueType();
unsigned Complexity = 0;
if (AM.BaseType == X86ISelAddressMode::RegBase)
if (AM.Base_Reg.getNode())
@ -1667,7 +1672,7 @@ bool X86DAGToDAGISel::selectLEAAddr(SDValue N,
if (Complexity <= 2)
return false;
getAddressOperands(AM, SDLoc(N), Base, Scale, Index, Disp, Segment);
getAddressOperands(AM, DL, Base, Scale, Index, Disp, Segment);
return true;
}