Commit 0e2f0d7a authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r257730: 

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r257730 | majnemer | 2016-01-13 17:20:03 -0800 (Wed, 13 Jan 2016) | 11 lines

[X86] Don't alter HasOpaqueSPAdjustment after we've relied on it

We rely on HasOpaqueSPAdjustment not changing after we've calculated
things based on it.  Things like whether or not we can use 'rep;movs' to
copy bytes around, that sort of thing.  If it changes, invariants in the
backend will quietly break.  This situation arose when we had a call to
memcpy *and* a COPY of the FLAGS register where we would attempt to
reference local variables using %esi, a register that was clobbered by
the 'rep;movs'.

This fixes PR26124.
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llvm-svn: 257779
parent 46669202

llvm/include/llvm/CodeGen/MachineFrameInfo.h

+14 −0
Original line number Diff line number Diff line
@@ -251,6 +251,10 @@ class MachineFrameInfo { 
  /// opaque mechanism like inline assembly or Win32 EH.

  bool HasOpaqueSPAdjustment;



  /// True if the function contains operations which will lower down to

  /// instructions which manipulate the stack pointer.

  bool HasCopyImplyingStackAdjustment;



  /// True if the function contains a call to the llvm.vastart intrinsic.

  bool HasVAStart;
@@ -288,6 +292,7 @@ public: 
    LocalFrameMaxAlign = 0;

    UseLocalStackAllocationBlock = false;

    HasOpaqueSPAdjustment = false;

    HasCopyImplyingStackAdjustment = false;

    HasVAStart = false;

    HasMustTailInVarArgFunc = false;

    Save = nullptr;
@@ -493,6 +498,15 @@ public: 
  bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; }

  void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; }



  /// Returns true if the function contains operations which will lower down to

  /// instructions which manipulate the stack pointer.

  bool hasCopyImplyingStackAdjustment() const {

    return HasCopyImplyingStackAdjustment;

  }

  void setHasCopyImplyingStackAdjustment(bool B) {

    HasCopyImplyingStackAdjustment = B;

  }



  /// Returns true if the function calls the llvm.va_start intrinsic.

  bool hasVAStart() const { return HasVAStart; }

  void setHasVAStart(bool B) { HasVAStart = B; }

llvm/include/llvm/Target/TargetLowering.h

+1 −1
Original line number Diff line number Diff line
@@ -2270,7 +2270,7 @@ public: 
  }



  /// Return true if the MachineFunction contains a COPY which would imply

  /// HasOpaqueSPAdjustment.

  /// HasCopyImplyingStackAdjustment.

  virtual bool hasCopyImplyingStackAdjustment(MachineFunction *MF) const {

    return false;

  }

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

+1 −1
Original line number Diff line number Diff line
@@ -634,7 +634,7 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) { 
  }



  if (TLI->hasCopyImplyingStackAdjustment(MF))

    MFI->setHasOpaqueSPAdjustment(true);

    MFI->setHasCopyImplyingStackAdjustment(true);



  // Freeze the set of reserved registers now that MachineFrameInfo has been

  // set up. All the information required by getReservedRegs() should be

llvm/lib/Target/X86/X86FrameLowering.cpp

+7 −6
Original line number Diff line number Diff line
@@ -91,7 +91,8 @@ bool X86FrameLowering::hasFP(const MachineFunction &MF) const { 
          MFI->isFrameAddressTaken() || MFI->hasOpaqueSPAdjustment() ||

          MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() ||

          MMI.callsUnwindInit() || MMI.hasEHFunclets() || MMI.callsEHReturn() ||

          MFI->hasStackMap() || MFI->hasPatchPoint());

          MFI->hasStackMap() || MFI->hasPatchPoint() ||

          MFI->hasCopyImplyingStackAdjustment());

}



static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) {
@@ -946,7 +947,7 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, 
      !MFI->hasVarSizedObjects() &&             // No dynamic alloca.

      !MFI->adjustsStack() &&                   // No calls.

      !IsWin64CC &&                             // Win64 has no Red Zone

      !MFI->hasOpaqueSPAdjustment() && // Don't push and pop.

      !MFI->hasCopyImplyingStackAdjustment() && // Don't push and pop.

      !MF.shouldSplitStack()) {                 // Regular stack

    uint64_t MinSize = X86FI->getCalleeSavedFrameSize();

    if (HasFP) MinSize += SlotSize;

llvm/lib/Target/X86/X86ISelLowering.cpp

+1 −1
Original line number Diff line number Diff line
@@ -17458,7 +17458,7 @@ static SDValue LowerINTRINSIC_W_CHAIN(SDValue Op, const X86Subtarget *Subtarget, 
      // We need a frame pointer because this will get lowered to a PUSH/POP

      // sequence.

      MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();

      MFI->setHasOpaqueSPAdjustment(true);

      MFI->setHasCopyImplyingStackAdjustment(true);

      // Don't do anything here, we will expand these intrinsics out later

      // during ExpandISelPseudos in EmitInstrWithCustomInserter.

      return SDValue();