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

4 files changed, 0 insertions, 41 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index de3df34ec44..073b4e01377 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1687,19 +1687,6 @@ bool X86TargetLowering::useLoadStackGuardNode() const {
   return Subtarget.isTargetMachO() && Subtarget.is64Bit();
 }
 
-bool X86TargetLowering::useStackGuardXorFP() const {
-  // Currently only MSVC CRTs XOR the frame pointer into the stack guard value.
-  return Subtarget.getTargetTriple().isOSMSVCRT();
-}
-
-SDValue X86TargetLowering::emitStackGuardXorFP(SelectionDAG &DAG, SDValue Val,
-                                               const SDLoc &DL) const {
-  EVT PtrTy = getPointerTy(DAG.getDataLayout());
-  unsigned XorOp = Subtarget.is64Bit() ? X86::XOR64_FP : X86::XOR32_FP;
-  MachineSDNode *Node = DAG.getMachineNode(XorOp, DL, PtrTy, Val);
-  return SDValue(Node, 0);
-}
-
 TargetLoweringBase::LegalizeTypeAction
 X86TargetLowering::getPreferredVectorAction(EVT VT) const {
   if (ExperimentalVectorWideningLegalization &&
diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
index d31104f9433..90830f4d5d1 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.h
+++ b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -1055,13 +1055,9 @@ namespace llvm {
     Value *getIRStackGuard(IRBuilder<> &IRB) const override;
 
     bool useLoadStackGuardNode() const override;
-    bool useStackGuardXorFP() const override;
     void insertSSPDeclarations(Module &M) const override;
     Value *getSDagStackGuard(const Module &M) const override;
     Value *getSSPStackGuardCheck(const Module &M) const override;
-    SDValue emitStackGuardXorFP(SelectionDAG &DAG, SDValue Val,
-                                const SDLoc &DL) const override;
-
 
     /// Return true if the target stores SafeStack pointer at a fixed offset in
     /// some non-standard address space, and populates the address space and
diff --git a/llvm/lib/Target/X86/X86InstrCompiler.td b/llvm/lib/Target/X86/X86InstrCompiler.td
index 4ff1a4f77c9..82885687bb4 100644
--- a/llvm/lib/Target/X86/X86InstrCompiler.td
+++ b/llvm/lib/Target/X86/X86InstrCompiler.td
@@ -142,15 +142,6 @@ def WIN_ALLOCA_64 : I<0, Pseudo, (outs), (ins GR64:$size),
                      [(X86WinAlloca GR64:$size)]>,
                      Requires<[In64BitMode]>;
 
-// These instructions XOR the frame pointer into a GPR. They are used in some
-// stack protection schemes. These are post-RA pseudos because we only know the
-// frame register after register allocation.
-let Constraints = "$src = $dst", isPseudo = 1 in {
-  def XOR32_FP : I<0, Pseudo, (outs GR32:$dst), (ins GR32:$src),
-                  "xorl\t$$FP, $src", []>, Requires<[NotLP64]>;
-  def XOR64_FP : I<0, Pseudo, (outs GR64:$dst), (ins GR64:$src),
-                  "xorq\t$$FP $src", []>, Requires<[In64BitMode]>;
-}
 
 //===----------------------------------------------------------------------===//
 // EH Pseudo Instructions
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;
 }