Revert r319490 "XOR the frame pointer with the stack cookie when protecting the stack"

This broke the Chromium build (crbug.com/791714). Reverting while investigating.

> Summary: This strengthens the guard and matches MSVC.
>
> Reviewers: hans, etienneb
>
> Subscribers: hiraditya, JDevlieghere, vlad.tsyrklevich, llvm-commits
>
> Differential Revision: https://reviews.llvm.org/D40622
>
> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319490 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-svn: 319706

1 files changed, 0 insertions, 15 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 96f19d35815..a5bff06e70b 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -7762,18 +7762,6 @@ static void expandLoadStackGuard(MachineInstrBuilder &MIB,
   MIB.addReg(Reg, RegState::Kill).addImm(1).addReg(0).addImm(0).addReg(0);
 }
 
-static bool expandXorFP(MachineInstrBuilder &MIB, const TargetInstrInfo &TII) {
-  MachineBasicBlock &MBB = *MIB->getParent();
-  MachineFunction &MF = *MBB.getParent();
-  const X86Subtarget &Subtarget = MF.getSubtarget<X86Subtarget>();
-  const X86RegisterInfo *TRI = Subtarget.getRegisterInfo();
-  unsigned XorOp =
-      MIB->getOpcode() == X86::XOR64_FP ? X86::XOR64rr : X86::XOR32rr;
-  MIB->setDesc(TII.get(XorOp));
-  MIB.addReg(TRI->getFrameRegister(MF), RegState::Undef);
-  return true;
-}
-
 // This is used to handle spills for 128/256-bit registers when we have AVX512,
 // but not VLX. If it uses an extended register we need to use an instruction
 // that loads the lower 128/256-bit, but is available with only AVX512F.
@@ -7968,9 +7956,6 @@ bool X86InstrInfo::expandPostRAPseudo(MachineInstr &MI) const {
   case TargetOpcode::LOAD_STACK_GUARD:
     expandLoadStackGuard(MIB, *this);
     return true;
-  case X86::XOR64_FP:
-  case X86::XOR32_FP:
-    return expandXorFP(MIB, *this);
   }
   return false;
 }