1 //===-- RISCVRegisterInfo.cpp - RISCV Register Information ------*- C++ -*-===//
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 // This file contains the RISCV implementation of the TargetRegisterInfo class.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "RISCVRegisterInfo.h"
15 #include "RISCV.h"
16 #include "RISCVSubtarget.h"
17 #include "llvm/CodeGen/MachineFrameInfo.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineInstrBuilder.h"
20 #include "llvm/CodeGen/RegisterScavenging.h"
21 #include "llvm/CodeGen/TargetFrameLowering.h"
22 #include "llvm/CodeGen/TargetInstrInfo.h"
23 #include "llvm/Support/ErrorHandling.h"
24
25 #define GET_REGINFO_TARGET_DESC
26 #include "RISCVGenRegisterInfo.inc"
27
28 using namespace llvm;
29
RISCVRegisterInfo(unsigned HwMode)30 RISCVRegisterInfo::RISCVRegisterInfo(unsigned HwMode)
31 : RISCVGenRegisterInfo(RISCV::X1, /*DwarfFlavour*/0, /*EHFlavor*/0,
32 /*PC*/0, HwMode) {}
33
34 const MCPhysReg *
getCalleeSavedRegs(const MachineFunction * MF) const35 RISCVRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
36 if (MF->getFunction().hasFnAttribute("interrupt")) {
37 if (MF->getSubtarget<RISCVSubtarget>().hasStdExtD())
38 return CSR_XLEN_F64_Interrupt_SaveList;
39 if (MF->getSubtarget<RISCVSubtarget>().hasStdExtF())
40 return CSR_XLEN_F32_Interrupt_SaveList;
41 return CSR_Interrupt_SaveList;
42 }
43 return CSR_SaveList;
44 }
45
getReservedRegs(const MachineFunction & MF) const46 BitVector RISCVRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
47 BitVector Reserved(getNumRegs());
48
49 // Use markSuperRegs to ensure any register aliases are also reserved
50 markSuperRegs(Reserved, RISCV::X0); // zero
51 markSuperRegs(Reserved, RISCV::X1); // ra
52 markSuperRegs(Reserved, RISCV::X2); // sp
53 markSuperRegs(Reserved, RISCV::X3); // gp
54 markSuperRegs(Reserved, RISCV::X4); // tp
55 markSuperRegs(Reserved, RISCV::X8); // fp
56 assert(checkAllSuperRegsMarked(Reserved));
57 return Reserved;
58 }
59
isConstantPhysReg(unsigned PhysReg) const60 bool RISCVRegisterInfo::isConstantPhysReg(unsigned PhysReg) const {
61 return PhysReg == RISCV::X0;
62 }
63
getNoPreservedMask() const64 const uint32_t *RISCVRegisterInfo::getNoPreservedMask() const {
65 return CSR_NoRegs_RegMask;
66 }
67
eliminateFrameIndex(MachineBasicBlock::iterator II,int SPAdj,unsigned FIOperandNum,RegScavenger * RS) const68 void RISCVRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
69 int SPAdj, unsigned FIOperandNum,
70 RegScavenger *RS) const {
71 assert(SPAdj == 0 && "Unexpected non-zero SPAdj value");
72
73 MachineInstr &MI = *II;
74 MachineFunction &MF = *MI.getParent()->getParent();
75 MachineRegisterInfo &MRI = MF.getRegInfo();
76 const RISCVInstrInfo *TII = MF.getSubtarget<RISCVSubtarget>().getInstrInfo();
77 DebugLoc DL = MI.getDebugLoc();
78
79 int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
80 unsigned FrameReg;
81 int Offset =
82 getFrameLowering(MF)->getFrameIndexReference(MF, FrameIndex, FrameReg) +
83 MI.getOperand(FIOperandNum + 1).getImm();
84
85 if (!isInt<32>(Offset)) {
86 report_fatal_error(
87 "Frame offsets outside of the signed 32-bit range not supported");
88 }
89
90 MachineBasicBlock &MBB = *MI.getParent();
91 bool FrameRegIsKill = false;
92
93 if (!isInt<12>(Offset)) {
94 assert(isInt<32>(Offset) && "Int32 expected");
95 // The offset won't fit in an immediate, so use a scratch register instead
96 // Modify Offset and FrameReg appropriately
97 unsigned ScratchReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
98 TII->movImm32(MBB, II, DL, ScratchReg, Offset);
99 BuildMI(MBB, II, DL, TII->get(RISCV::ADD), ScratchReg)
100 .addReg(FrameReg)
101 .addReg(ScratchReg, RegState::Kill);
102 Offset = 0;
103 FrameReg = ScratchReg;
104 FrameRegIsKill = true;
105 }
106
107 MI.getOperand(FIOperandNum)
108 .ChangeToRegister(FrameReg, false, false, FrameRegIsKill);
109 MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
110 }
111
getFrameRegister(const MachineFunction & MF) const112 unsigned RISCVRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
113 const TargetFrameLowering *TFI = getFrameLowering(MF);
114 return TFI->hasFP(MF) ? RISCV::X8 : RISCV::X2;
115 }
116
117 const uint32_t *
getCallPreservedMask(const MachineFunction & MF,CallingConv::ID) const118 RISCVRegisterInfo::getCallPreservedMask(const MachineFunction & MF,
119 CallingConv::ID /*CC*/) const {
120 if (MF.getFunction().hasFnAttribute("interrupt")) {
121 if (MF.getSubtarget<RISCVSubtarget>().hasStdExtD())
122 return CSR_XLEN_F64_Interrupt_RegMask;
123 if (MF.getSubtarget<RISCVSubtarget>().hasStdExtF())
124 return CSR_XLEN_F32_Interrupt_RegMask;
125 return CSR_Interrupt_RegMask;
126 }
127 return CSR_RegMask;
128 }
129