| //===----- TargetFrameLoweringImpl.cpp - Implement target frame interface --==// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Implements the layout of a stack frame on the target machine. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/ADT/BitVector.h" |
| #include "llvm/Target/TargetFrameLowering.h" |
| #include "llvm/CodeGen/MachineFrameInfo.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineModuleInfo.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/Target/TargetRegisterInfo.h" |
| #include "llvm/Target/TargetSubtargetInfo.h" |
| #include <cstdlib> |
| using namespace llvm; |
| |
| TargetFrameLowering::~TargetFrameLowering() { |
| } |
| |
| /// The default implementation just looks at attribute "no-frame-pointer-elim". |
| bool TargetFrameLowering::noFramePointerElim(const MachineFunction &MF) const { |
| auto Attr = MF.getFunction()->getFnAttribute("no-frame-pointer-elim"); |
| return Attr.getValueAsString() == "true"; |
| } |
| |
| /// getFrameIndexOffset - Returns the displacement from the frame register to |
| /// the stack frame of the specified index. This is the default implementation |
| /// which is overridden for some targets. |
| int TargetFrameLowering::getFrameIndexOffset(const MachineFunction &MF, |
| int FI) const { |
| const MachineFrameInfo *MFI = MF.getFrameInfo(); |
| return MFI->getObjectOffset(FI) + MFI->getStackSize() - |
| getOffsetOfLocalArea() + MFI->getOffsetAdjustment(); |
| } |
| |
| int TargetFrameLowering::getFrameIndexReference(const MachineFunction &MF, |
| int FI, unsigned &FrameReg) const { |
| const TargetRegisterInfo *RI = MF.getSubtarget().getRegisterInfo(); |
| |
| // By default, assume all frame indices are referenced via whatever |
| // getFrameRegister() says. The target can override this if it's doing |
| // something different. |
| FrameReg = RI->getFrameRegister(MF); |
| return getFrameIndexOffset(MF, FI); |
| } |
| |
| bool TargetFrameLowering::needsFrameIndexResolution( |
| const MachineFunction &MF) const { |
| return MF.getFrameInfo()->hasStackObjects(); |
| } |
| |
| void TargetFrameLowering::determineCalleeSaves(MachineFunction &MF, |
| BitVector &SavedRegs, |
| RegScavenger *RS) const { |
| // Get the callee saved register list... |
| const TargetRegisterInfo &TRI = *MF.getSubtarget().getRegisterInfo(); |
| const MCPhysReg *CSRegs = TRI.getCalleeSavedRegs(&MF); |
| |
| // Early exit if there are no callee saved registers. |
| if (!CSRegs || CSRegs[0] == 0) |
| return; |
| |
| SavedRegs.resize(TRI.getNumRegs()); |
| |
| // In Naked functions we aren't going to save any registers. |
| if (MF.getFunction()->hasFnAttribute(Attribute::Naked)) |
| return; |
| |
| // Functions which call __builtin_unwind_init get all their registers saved. |
| bool CallsUnwindInit = MF.getMMI().callsUnwindInit(); |
| const MachineRegisterInfo &MRI = MF.getRegInfo(); |
| for (unsigned i = 0; CSRegs[i]; ++i) { |
| unsigned Reg = CSRegs[i]; |
| if (CallsUnwindInit || MRI.isPhysRegModified(Reg)) |
| SavedRegs.set(Reg); |
| } |
| } |