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//===-------------- PPCVSXCopy.cpp - VSX Copy Legalization ----------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// A pass which deals with the complexity of generating legal VSX register
// copies to/from register classes which partially overlap with the VSX
// register file.
#include "MCTargetDesc/PPCPredicates.h"
#include "PPC.h"
#include "PPCHazardRecognizers.h"
#include "PPCInstrBuilder.h"
#include "PPCInstrInfo.h"
#include "PPCMachineFunctionInfo.h"
#include "PPCTargetMachine.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "ppc-vsx-copy"
namespace {
// PPCVSXCopy pass - For copies between VSX registers and non-VSX registers
// (Altivec and scalar floating-point registers), we need to transform the
// copies into subregister copies with other restrictions.
struct PPCVSXCopy : public MachineFunctionPass {
static char ID;
PPCVSXCopy() : MachineFunctionPass(ID) {
const TargetInstrInfo *TII;
bool IsRegInClass(unsigned Reg, const TargetRegisterClass *RC,
MachineRegisterInfo &MRI) {
if (Register::isVirtualRegister(Reg)) {
return RC->hasSubClassEq(MRI.getRegClass(Reg));
} else if (RC->contains(Reg)) {
return true;
return false;
bool IsVSReg(unsigned Reg, MachineRegisterInfo &MRI) {
return IsRegInClass(Reg, &PPC::VSRCRegClass, MRI);
bool IsVRReg(unsigned Reg, MachineRegisterInfo &MRI) {
return IsRegInClass(Reg, &PPC::VRRCRegClass, MRI);
bool IsF8Reg(unsigned Reg, MachineRegisterInfo &MRI) {
return IsRegInClass(Reg, &PPC::F8RCRegClass, MRI);
bool IsVSFReg(unsigned Reg, MachineRegisterInfo &MRI) {
return IsRegInClass(Reg, &PPC::VSFRCRegClass, MRI);
bool IsVSSReg(unsigned Reg, MachineRegisterInfo &MRI) {
return IsRegInClass(Reg, &PPC::VSSRCRegClass, MRI);
bool processBlock(MachineBasicBlock &MBB) {
bool Changed = false;
MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
for (MachineInstr &MI : MBB) {
if (!MI.isFullCopy())
MachineOperand &DstMO = MI.getOperand(0);
MachineOperand &SrcMO = MI.getOperand(1);
if ( IsVSReg(DstMO.getReg(), MRI) &&
!IsVSReg(SrcMO.getReg(), MRI)) {
// This is a copy *to* a VSX register from a non-VSX register.
Changed = true;
const TargetRegisterClass *SrcRC = &PPC::VSLRCRegClass;
assert((IsF8Reg(SrcMO.getReg(), MRI) ||
IsVSSReg(SrcMO.getReg(), MRI) ||
IsVSFReg(SrcMO.getReg(), MRI)) &&
"Unknown source for a VSX copy");
Register NewVReg = MRI.createVirtualRegister(SrcRC);
BuildMI(MBB, MI, MI.getDebugLoc(),
TII->get(TargetOpcode::SUBREG_TO_REG), NewVReg)
.addImm(1) // add 1, not 0, because there is no implicit clearing
// of the high bits.
// The source of the original copy is now the new virtual register.
} else if (!IsVSReg(DstMO.getReg(), MRI) &&
IsVSReg(SrcMO.getReg(), MRI)) {
// This is a copy *from* a VSX register to a non-VSX register.
Changed = true;
const TargetRegisterClass *DstRC = &PPC::VSLRCRegClass;
assert((IsF8Reg(DstMO.getReg(), MRI) ||
IsVSFReg(DstMO.getReg(), MRI) ||
IsVSSReg(DstMO.getReg(), MRI)) &&
"Unknown destination for a VSX copy");
// Copy the VSX value into a new VSX register of the correct subclass.
Register NewVReg = MRI.createVirtualRegister(DstRC);
BuildMI(MBB, MI, MI.getDebugLoc(), TII->get(TargetOpcode::COPY),
// Transform the original copy into a subregister extraction copy.
return Changed;
bool runOnMachineFunction(MachineFunction &MF) override {
// If we don't have VSX on the subtarget, don't do anything.
const PPCSubtarget &STI = MF.getSubtarget<PPCSubtarget>();
if (!STI.hasVSX())
return false;
TII = STI.getInstrInfo();
bool Changed = false;
for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
MachineBasicBlock &B = *I++;
if (processBlock(B))
Changed = true;
return Changed;
void getAnalysisUsage(AnalysisUsage &AU) const override {
"PowerPC VSX Copy Legalization", false, false)
char PPCVSXCopy::ID = 0;
llvm::createPPCVSXCopyPass() { return new PPCVSXCopy(); }