1//===-------------- PPCVSXCopy.cpp - VSX Copy Legalization ----------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// A pass which deals with the complexity of generating legal VSX register
10// copies to/from register classes which partially overlap with the VSX
11// register file.
12//
13//===----------------------------------------------------------------------===//
14
15#include "MCTargetDesc/PPCPredicates.h"
16#include "PPC.h"
17#include "PPCHazardRecognizers.h"
18#include "PPCInstrBuilder.h"
19#include "PPCInstrInfo.h"
20#include "PPCMachineFunctionInfo.h"
21#include "PPCTargetMachine.h"
22#include "llvm/ADT/STLExtras.h"
23#include "llvm/ADT/Statistic.h"
24#include "llvm/CodeGen/MachineFrameInfo.h"
25#include "llvm/CodeGen/MachineFunctionPass.h"
26#include "llvm/CodeGen/MachineInstrBuilder.h"
27#include "llvm/CodeGen/MachineMemOperand.h"
28#include "llvm/CodeGen/MachineRegisterInfo.h"
29#include "llvm/MC/MCAsmInfo.h"
30#include "llvm/MC/TargetRegistry.h"
31#include "llvm/Support/Debug.h"
32#include "llvm/Support/ErrorHandling.h"
33#include "llvm/Support/raw_ostream.h"
34
35using namespace llvm;
36
37#define DEBUG_TYPE "ppc-vsx-copy"
38
39namespace {
40 // PPCVSXCopy pass - For copies between VSX registers and non-VSX registers
41 // (Altivec and scalar floating-point registers), we need to transform the
42 // copies into subregister copies with other restrictions.
43 struct PPCVSXCopy : public MachineFunctionPass {
44 static char ID;
45 PPCVSXCopy() : MachineFunctionPass(ID) {
46 initializePPCVSXCopyPass(*PassRegistry::getPassRegistry());
47 }
48
49 const TargetInstrInfo *TII;
50
51 bool IsRegInClass(unsigned Reg, const TargetRegisterClass *RC,
52 MachineRegisterInfo &MRI) {
53 if (Register::isVirtualRegister(Reg)) {
54 return RC->hasSubClassEq(RC: MRI.getRegClass(Reg));
55 } else if (RC->contains(Reg)) {
56 return true;
57 }
58
59 return false;
60 }
61
62 bool IsVSReg(unsigned Reg, MachineRegisterInfo &MRI) {
63 return IsRegInClass(Reg, RC: &PPC::VSRCRegClass, MRI);
64 }
65
66 bool IsVRReg(unsigned Reg, MachineRegisterInfo &MRI) {
67 return IsRegInClass(Reg, RC: &PPC::VRRCRegClass, MRI);
68 }
69
70 bool IsF8Reg(unsigned Reg, MachineRegisterInfo &MRI) {
71 return IsRegInClass(Reg, RC: &PPC::F8RCRegClass, MRI);
72 }
73
74 bool IsVSFReg(unsigned Reg, MachineRegisterInfo &MRI) {
75 return IsRegInClass(Reg, RC: &PPC::VSFRCRegClass, MRI);
76 }
77
78 bool IsVSSReg(unsigned Reg, MachineRegisterInfo &MRI) {
79 return IsRegInClass(Reg, RC: &PPC::VSSRCRegClass, MRI);
80 }
81
82protected:
83 bool processBlock(MachineBasicBlock &MBB) {
84 bool Changed = false;
85
86 MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
87 for (MachineInstr &MI : MBB) {
88 if (!MI.isFullCopy())
89 continue;
90
91 MachineOperand &DstMO = MI.getOperand(i: 0);
92 MachineOperand &SrcMO = MI.getOperand(i: 1);
93
94 if ( IsVSReg(Reg: DstMO.getReg(), MRI) &&
95 !IsVSReg(Reg: SrcMO.getReg(), MRI)) {
96 // This is a copy *to* a VSX register from a non-VSX register.
97 Changed = true;
98
99 const TargetRegisterClass *SrcRC = &PPC::VSLRCRegClass;
100 assert((IsF8Reg(SrcMO.getReg(), MRI) ||
101 IsVSSReg(SrcMO.getReg(), MRI) ||
102 IsVSFReg(SrcMO.getReg(), MRI)) &&
103 "Unknown source for a VSX copy");
104
105 Register NewVReg = MRI.createVirtualRegister(RegClass: SrcRC);
106 BuildMI(BB&: MBB, I&: MI, MIMD: MI.getDebugLoc(),
107 MCID: TII->get(Opcode: TargetOpcode::SUBREG_TO_REG), DestReg: NewVReg)
108 .addImm(Val: 1) // add 1, not 0, because there is no implicit clearing
109 // of the high bits.
110 .add(MO: SrcMO)
111 .addImm(Val: PPC::sub_64);
112
113 // The source of the original copy is now the new virtual register.
114 SrcMO.setReg(NewVReg);
115 } else if (!IsVSReg(Reg: DstMO.getReg(), MRI) &&
116 IsVSReg(Reg: SrcMO.getReg(), MRI)) {
117 // This is a copy *from* a VSX register to a non-VSX register.
118 Changed = true;
119
120 const TargetRegisterClass *DstRC = &PPC::VSLRCRegClass;
121 assert((IsF8Reg(DstMO.getReg(), MRI) ||
122 IsVSFReg(DstMO.getReg(), MRI) ||
123 IsVSSReg(DstMO.getReg(), MRI)) &&
124 "Unknown destination for a VSX copy");
125
126 // Copy the VSX value into a new VSX register of the correct subclass.
127 Register NewVReg = MRI.createVirtualRegister(RegClass: DstRC);
128 BuildMI(BB&: MBB, I&: MI, MIMD: MI.getDebugLoc(), MCID: TII->get(Opcode: TargetOpcode::COPY),
129 DestReg: NewVReg)
130 .add(MO: SrcMO);
131
132 // Transform the original copy into a subregister extraction copy.
133 SrcMO.setReg(NewVReg);
134 SrcMO.setSubReg(PPC::sub_64);
135 }
136 }
137
138 return Changed;
139 }
140
141public:
142 bool runOnMachineFunction(MachineFunction &MF) override {
143 // If we don't have VSX on the subtarget, don't do anything.
144 const PPCSubtarget &STI = MF.getSubtarget<PPCSubtarget>();
145 if (!STI.hasVSX())
146 return false;
147 TII = STI.getInstrInfo();
148
149 bool Changed = false;
150
151 for (MachineBasicBlock &B : llvm::make_early_inc_range(Range&: MF))
152 if (processBlock(MBB&: B))
153 Changed = true;
154
155 return Changed;
156 }
157
158 void getAnalysisUsage(AnalysisUsage &AU) const override {
159 MachineFunctionPass::getAnalysisUsage(AU);
160 }
161 };
162}
163
164INITIALIZE_PASS(PPCVSXCopy, DEBUG_TYPE,
165 "PowerPC VSX Copy Legalization", false, false)
166
167char PPCVSXCopy::ID = 0;
168FunctionPass*
169llvm::createPPCVSXCopyPass() { return new PPCVSXCopy(); }
170