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https://github.com/c64scene-ar/llvm-6502.git
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fe47bf8fa0
This builds on some frame-lowering code that has existed since 2005 (r24224) but was disabled in 2008 (r48188) because it needed base pointer support to function correctly. This implementation follows the strategy suggested by Dale Johannesen in r48188 where the following comment was added: This does not currently work, because the delta between old and new stack pointers is added to offsets that reference incoming parameters after the prolog is generated, and the code that does that doesn't handle a variable delta. You don't want to do that anyway; a better approach is to reserve another register that retains to the incoming stack pointer, and reference parameters relative to that. And now we do exactly that. If we don't need a frame pointer, then we use r31 as a base pointer. If we do need a frame pointer, then we use r30 as a base pointer. The base pointer retains the value of the stack pointer before it was decremented in the prologue. We then use the base pointer to resolve all negative frame indicies. The basic scheme follows that for base pointers in the X86 backend. We use a base pointer when we need to dynamically realign the incoming stack pointer. This currently applies only to static objects (dynamic allocas with large alignments, and base-pointer support in SjLj lowering will come in future commits). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186478 91177308-0d34-0410-b5e6-96231b3b80d8
109 lines
3.7 KiB
C++
109 lines
3.7 KiB
C++
//===-- PPCRegisterInfo.h - PowerPC Register Information Impl ---*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the PowerPC implementation of the TargetRegisterInfo
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// class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef POWERPC32_REGISTERINFO_H
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#define POWERPC32_REGISTERINFO_H
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#include "llvm/ADT/DenseMap.h"
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#include "PPC.h"
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#define GET_REGINFO_HEADER
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#include "PPCGenRegisterInfo.inc"
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namespace llvm {
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class PPCSubtarget;
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class TargetInstrInfo;
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class Type;
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class PPCRegisterInfo : public PPCGenRegisterInfo {
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DenseMap<unsigned, unsigned> ImmToIdxMap;
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const PPCSubtarget &Subtarget;
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public:
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PPCRegisterInfo(const PPCSubtarget &SubTarget);
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/// getPointerRegClass - Return the register class to use to hold pointers.
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/// This is used for addressing modes.
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virtual const TargetRegisterClass *
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getPointerRegClass(const MachineFunction &MF, unsigned Kind=0) const;
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unsigned getRegPressureLimit(const TargetRegisterClass *RC,
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MachineFunction &MF) const;
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/// Code Generation virtual methods...
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const uint16_t *getCalleeSavedRegs(const MachineFunction* MF = 0) const;
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const uint32_t *getCallPreservedMask(CallingConv::ID CC) const;
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const uint32_t *getNoPreservedMask() const;
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BitVector getReservedRegs(const MachineFunction &MF) const;
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/// We require the register scavenger.
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bool requiresRegisterScavenging(const MachineFunction &MF) const {
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return true;
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}
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bool requiresFrameIndexScavenging(const MachineFunction &MF) const {
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return true;
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}
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bool trackLivenessAfterRegAlloc(const MachineFunction &MF) const {
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return true;
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}
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virtual bool requiresVirtualBaseRegisters(const MachineFunction &MF) const {
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return true;
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}
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void lowerDynamicAlloc(MachineBasicBlock::iterator II) const;
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void lowerCRSpilling(MachineBasicBlock::iterator II,
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unsigned FrameIndex) const;
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void lowerCRRestore(MachineBasicBlock::iterator II,
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unsigned FrameIndex) const;
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void lowerVRSAVESpilling(MachineBasicBlock::iterator II,
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unsigned FrameIndex) const;
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void lowerVRSAVERestore(MachineBasicBlock::iterator II,
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unsigned FrameIndex) const;
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bool hasReservedSpillSlot(const MachineFunction &MF, unsigned Reg,
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int &FrameIdx) const;
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void eliminateFrameIndex(MachineBasicBlock::iterator II,
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int SPAdj, unsigned FIOperandNum,
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RegScavenger *RS = NULL) const;
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// Support for virtual base registers.
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bool needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const;
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void materializeFrameBaseRegister(MachineBasicBlock *MBB,
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unsigned BaseReg, int FrameIdx,
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int64_t Offset) const;
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void resolveFrameIndex(MachineBasicBlock::iterator I,
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unsigned BaseReg, int64_t Offset) const;
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bool isFrameOffsetLegal(const MachineInstr *MI, int64_t Offset) const;
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// Debug information queries.
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unsigned getFrameRegister(const MachineFunction &MF) const;
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// Base pointer (stack realignment) support.
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unsigned getBaseRegister(const MachineFunction &MF) const;
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bool hasBasePointer(const MachineFunction &MF) const;
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bool canRealignStack(const MachineFunction &MF) const;
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bool needsStackRealignment(const MachineFunction &MF) const;
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// Exception handling queries.
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unsigned getEHExceptionRegister() const;
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unsigned getEHHandlerRegister() const;
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};
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} // end namespace llvm
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#endif
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