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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123399 91177308-0d34-0410-b5e6-96231b3b80d8
144 lines
4.9 KiB
C++
144 lines
4.9 KiB
C++
//=====- AlphaFrameLowering.cpp - Alpha Frame Information ------*- 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 Alpha implementation of TargetFrameLowering class.
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//
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//===----------------------------------------------------------------------===//
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#include "AlphaFrameLowering.h"
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#include "AlphaInstrInfo.h"
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#include "AlphaMachineFunctionInfo.h"
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#include "llvm/Function.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/ADT/Twine.h"
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using namespace llvm;
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static long getUpper16(long l) {
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long y = l / Alpha::IMM_MULT;
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if (l % Alpha::IMM_MULT > Alpha::IMM_HIGH)
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++y;
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return y;
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}
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static long getLower16(long l) {
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long h = getUpper16(l);
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return l - h * Alpha::IMM_MULT;
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}
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// hasFP - Return true if the specified function should have a dedicated frame
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// pointer register. This is true if the function has variable sized allocas or
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// if frame pointer elimination is disabled.
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//
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bool AlphaFrameLowering::hasFP(const MachineFunction &MF) const {
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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return MFI->hasVarSizedObjects();
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}
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void AlphaFrameLowering::emitPrologue(MachineFunction &MF) const {
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MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
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MachineBasicBlock::iterator MBBI = MBB.begin();
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MachineFrameInfo *MFI = MF.getFrameInfo();
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const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
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DebugLoc dl = (MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc());
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bool FP = hasFP(MF);
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// Handle GOP offset
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAHg), Alpha::R29)
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.addGlobalAddress(MF.getFunction()).addReg(Alpha::R27).addImm(++curgpdist);
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAg), Alpha::R29)
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.addGlobalAddress(MF.getFunction()).addReg(Alpha::R29).addImm(curgpdist);
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::ALTENT))
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.addGlobalAddress(MF.getFunction());
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// Get the number of bytes to allocate from the FrameInfo
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long NumBytes = MFI->getStackSize();
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if (FP)
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NumBytes += 8; //reserve space for the old FP
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// Do we need to allocate space on the stack?
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if (NumBytes == 0) return;
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unsigned Align = getStackAlignment();
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NumBytes = (NumBytes+Align-1)/Align*Align;
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// Update frame info to pretend that this is part of the stack...
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MFI->setStackSize(NumBytes);
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// adjust stack pointer: r30 -= numbytes
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NumBytes = -NumBytes;
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if (NumBytes >= Alpha::IMM_LOW) {
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30).addImm(NumBytes)
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.addReg(Alpha::R30);
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} else if (getUpper16(NumBytes) >= Alpha::IMM_LOW) {
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAH), Alpha::R30)
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.addImm(getUpper16(NumBytes)).addReg(Alpha::R30);
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30)
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.addImm(getLower16(NumBytes)).addReg(Alpha::R30);
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} else {
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report_fatal_error("Too big a stack frame at " + Twine(NumBytes));
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}
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// Now if we need to, save the old FP and set the new
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if (FP) {
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::STQ))
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.addReg(Alpha::R15).addImm(0).addReg(Alpha::R30);
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// This must be the last instr in the prolog
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::BISr), Alpha::R15)
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.addReg(Alpha::R30).addReg(Alpha::R30);
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}
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}
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void AlphaFrameLowering::emitEpilogue(MachineFunction &MF,
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MachineBasicBlock &MBB) const {
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
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const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
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assert((MBBI->getOpcode() == Alpha::RETDAG ||
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MBBI->getOpcode() == Alpha::RETDAGp)
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&& "Can only insert epilog into returning blocks");
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DebugLoc dl = MBBI->getDebugLoc();
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bool FP = hasFP(MF);
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// Get the number of bytes allocated from the FrameInfo...
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long NumBytes = MFI->getStackSize();
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//now if we need to, restore the old FP
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if (FP) {
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//copy the FP into the SP (discards allocas)
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::BISr), Alpha::R30).addReg(Alpha::R15)
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.addReg(Alpha::R15);
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//restore the FP
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDQ), Alpha::R15)
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.addImm(0).addReg(Alpha::R15);
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}
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if (NumBytes != 0) {
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if (NumBytes <= Alpha::IMM_HIGH) {
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30).addImm(NumBytes)
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.addReg(Alpha::R30);
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} else if (getUpper16(NumBytes) <= Alpha::IMM_HIGH) {
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDAH), Alpha::R30)
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.addImm(getUpper16(NumBytes)).addReg(Alpha::R30);
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BuildMI(MBB, MBBI, dl, TII.get(Alpha::LDA), Alpha::R30)
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.addImm(getLower16(NumBytes)).addReg(Alpha::R30);
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} else {
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report_fatal_error("Too big a stack frame at " + Twine(NumBytes));
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}
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}
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}
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