1 //===----- TargetFrameLoweringImpl.cpp - Implement target frame interface --==// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // Implements the layout of a stack frame on the target machine. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Target/TargetFrameLowering.h" 15 #include "llvm/CodeGen/MachineFrameInfo.h" 16 #include "llvm/CodeGen/MachineFunction.h" 17 #include "llvm/IR/Function.h" 18 #include "llvm/Target/TargetRegisterInfo.h" 19 #include "llvm/Target/TargetSubtargetInfo.h" 20 #include <cstdlib> 21 using namespace llvm; 22 23 TargetFrameLowering::~TargetFrameLowering() { 24 } 25 26 /// The default implementation just looks at attribute "no-frame-pointer-elim". 27 bool TargetFrameLowering::noFramePointerElim(const MachineFunction &MF) const { 28 auto Attr = MF.getFunction()->getFnAttribute("no-frame-pointer-elim"); 29 return Attr.getValueAsString() == "true"; 30 } 31 32 /// getFrameIndexOffset - Returns the displacement from the frame register to 33 /// the stack frame of the specified index. This is the default implementation 34 /// which is overridden for some targets. 35 int TargetFrameLowering::getFrameIndexOffset(const MachineFunction &MF, 36 int FI) const { 37 const MachineFrameInfo *MFI = MF.getFrameInfo(); 38 return MFI->getObjectOffset(FI) + MFI->getStackSize() - 39 getOffsetOfLocalArea() + MFI->getOffsetAdjustment(); 40 } 41 42 int TargetFrameLowering::getFrameIndexReference(const MachineFunction &MF, 43 int FI, unsigned &FrameReg) const { 44 const TargetRegisterInfo *RI = MF.getSubtarget().getRegisterInfo(); 45 46 // By default, assume all frame indices are referenced via whatever 47 // getFrameRegister() says. The target can override this if it's doing 48 // something different. 49 FrameReg = RI->getFrameRegister(MF); 50 return getFrameIndexOffset(MF, FI); 51 } 52 53 bool TargetFrameLowering::needsFrameIndexResolution( 54 const MachineFunction &MF) const { 55 return MF.getFrameInfo()->hasStackObjects(); 56 } 57