1//===-- RISCVBaseInfo.cpp - Top level definitions for RISC-V MC -----------===//
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// This file contains small standalone enum definitions for the RISC-V target
10// useful for the compiler back-end and the MC libraries.
11//
12//===----------------------------------------------------------------------===//
13
14#include "RISCVBaseInfo.h"
15#include "llvm/ADT/ArrayRef.h"
16#include "llvm/MC/MCInst.h"
17#include "llvm/MC/MCRegisterInfo.h"
18#include "llvm/MC/MCSubtargetInfo.h"
19#include "llvm/Support/raw_ostream.h"
20#include "llvm/TargetParser/TargetParser.h"
21#include "llvm/TargetParser/Triple.h"
22
23namespace llvm {
24
25extern const SubtargetFeatureKV RISCVFeatureKV[RISCV::NumSubtargetFeatures];
26
27namespace RISCVSysReg {
28#define GET_SysRegsList_IMPL
29#include "RISCVGenSearchableTables.inc"
30} // namespace RISCVSysReg
31
32namespace RISCVInsnOpcode {
33#define GET_RISCVOpcodesList_IMPL
34#include "RISCVGenSearchableTables.inc"
35} // namespace RISCVInsnOpcode
36
37namespace RISCVABI {
38ABI computeTargetABI(const Triple &TT, const FeatureBitset &FeatureBits,
39 StringRef ABIName) {
40 auto TargetABI = getTargetABI(ABIName);
41 bool IsRV64 = TT.isArch64Bit();
42 bool IsRVE = FeatureBits[RISCV::FeatureStdExtE];
43
44 if (!ABIName.empty() && TargetABI == ABI_Unknown) {
45 errs()
46 << "'" << ABIName
47 << "' is not a recognized ABI for this target (ignoring target-abi)\n";
48 } else if (ABIName.starts_with(Prefix: "ilp32") && IsRV64) {
49 errs() << "32-bit ABIs are not supported for 64-bit targets (ignoring "
50 "target-abi)\n";
51 TargetABI = ABI_Unknown;
52 } else if (ABIName.starts_with(Prefix: "lp64") && !IsRV64) {
53 errs() << "64-bit ABIs are not supported for 32-bit targets (ignoring "
54 "target-abi)\n";
55 TargetABI = ABI_Unknown;
56 } else if (!IsRV64 && IsRVE && TargetABI != ABI_ILP32E &&
57 TargetABI != ABI_Unknown) {
58 // TODO: move this checking to RISCVTargetLowering and RISCVAsmParser
59 errs()
60 << "Only the ilp32e ABI is supported for RV32E (ignoring target-abi)\n";
61 TargetABI = ABI_Unknown;
62 } else if (IsRV64 && IsRVE && TargetABI != ABI_LP64E &&
63 TargetABI != ABI_Unknown) {
64 // TODO: move this checking to RISCVTargetLowering and RISCVAsmParser
65 errs()
66 << "Only the lp64e ABI is supported for RV64E (ignoring target-abi)\n";
67 TargetABI = ABI_Unknown;
68 }
69
70 if ((TargetABI == RISCVABI::ABI::ABI_ILP32E ||
71 (TargetABI == ABI_Unknown && IsRVE && !IsRV64)) &&
72 FeatureBits[RISCV::FeatureStdExtD])
73 report_fatal_error(reason: "ILP32E cannot be used with the D ISA extension");
74
75 if (TargetABI != ABI_Unknown)
76 return TargetABI;
77
78 // If no explicit ABI is given, try to compute the default ABI.
79 auto ISAInfo = RISCVFeatures::parseFeatureBits(IsRV64, FeatureBits);
80 if (!ISAInfo)
81 report_fatal_error(Err: ISAInfo.takeError());
82 return getTargetABI(ABIName: (*ISAInfo)->computeDefaultABI());
83}
84
85ABI getTargetABI(StringRef ABIName) {
86 auto TargetABI = StringSwitch<ABI>(ABIName)
87 .Case(S: "ilp32", Value: ABI_ILP32)
88 .Case(S: "ilp32f", Value: ABI_ILP32F)
89 .Case(S: "ilp32d", Value: ABI_ILP32D)
90 .Case(S: "ilp32e", Value: ABI_ILP32E)
91 .Case(S: "lp64", Value: ABI_LP64)
92 .Case(S: "lp64f", Value: ABI_LP64F)
93 .Case(S: "lp64d", Value: ABI_LP64D)
94 .Case(S: "lp64e", Value: ABI_LP64E)
95 .Default(Value: ABI_Unknown);
96 return TargetABI;
97}
98
99// To avoid the BP value clobbered by a function call, we need to choose a
100// callee saved register to save the value. RV32E only has X8 and X9 as callee
101// saved registers and X8 will be used as fp. So we choose X9 as bp.
102MCRegister getBPReg() { return RISCV::X9; }
103
104// Returns the register holding shadow call stack pointer.
105MCRegister getSCSPReg() { return RISCV::X3; }
106
107} // namespace RISCVABI
108
109namespace RISCVFeatures {
110
111void validate(const Triple &TT, const FeatureBitset &FeatureBits) {
112 if (TT.isArch64Bit() && !FeatureBits[RISCV::Feature64Bit])
113 report_fatal_error(reason: "RV64 target requires an RV64 CPU");
114 if (!TT.isArch64Bit() && !FeatureBits[RISCV::Feature32Bit])
115 report_fatal_error(reason: "RV32 target requires an RV32 CPU");
116 if (FeatureBits[RISCV::Feature32Bit] &&
117 FeatureBits[RISCV::Feature64Bit])
118 report_fatal_error(reason: "RV32 and RV64 can't be combined");
119}
120
121llvm::Expected<std::unique_ptr<RISCVISAInfo>>
122parseFeatureBits(bool IsRV64, const FeatureBitset &FeatureBits) {
123 unsigned XLen = IsRV64 ? 64 : 32;
124 std::vector<std::string> FeatureVector;
125 // Convert FeatureBitset to FeatureVector.
126 for (auto Feature : RISCVFeatureKV) {
127 if (FeatureBits[Feature.Value] &&
128 llvm::RISCVISAInfo::isSupportedExtensionFeature(Ext: Feature.Key))
129 FeatureVector.push_back(x: std::string("+") + Feature.Key);
130 }
131 return llvm::RISCVISAInfo::parseFeatures(XLen, Features: FeatureVector);
132}
133
134} // namespace RISCVFeatures
135
136// Include the auto-generated portion of the compress emitter.
137#define GEN_UNCOMPRESS_INSTR
138#define GEN_COMPRESS_INSTR
139#include "RISCVGenCompressInstEmitter.inc"
140
141bool RISCVRVC::compress(MCInst &OutInst, const MCInst &MI,
142 const MCSubtargetInfo &STI) {
143 return compressInst(OutInst, MI, STI);
144}
145
146bool RISCVRVC::uncompress(MCInst &OutInst, const MCInst &MI,
147 const MCSubtargetInfo &STI) {
148 return uncompressInst(OutInst, MI, STI);
149}
150
151// Lookup table for fli.s for entries 2-31.
152static constexpr std::pair<uint8_t, uint8_t> LoadFP32ImmArr[] = {
153 {0b01101111, 0b00}, {0b01110000, 0b00}, {0b01110111, 0b00},
154 {0b01111000, 0b00}, {0b01111011, 0b00}, {0b01111100, 0b00},
155 {0b01111101, 0b00}, {0b01111101, 0b01}, {0b01111101, 0b10},
156 {0b01111101, 0b11}, {0b01111110, 0b00}, {0b01111110, 0b01},
157 {0b01111110, 0b10}, {0b01111110, 0b11}, {0b01111111, 0b00},
158 {0b01111111, 0b01}, {0b01111111, 0b10}, {0b01111111, 0b11},
159 {0b10000000, 0b00}, {0b10000000, 0b01}, {0b10000000, 0b10},
160 {0b10000001, 0b00}, {0b10000010, 0b00}, {0b10000011, 0b00},
161 {0b10000110, 0b00}, {0b10000111, 0b00}, {0b10001110, 0b00},
162 {0b10001111, 0b00}, {0b11111111, 0b00}, {0b11111111, 0b10},
163};
164
165int RISCVLoadFPImm::getLoadFPImm(APFloat FPImm) {
166 assert((&FPImm.getSemantics() == &APFloat::IEEEsingle() ||
167 &FPImm.getSemantics() == &APFloat::IEEEdouble() ||
168 &FPImm.getSemantics() == &APFloat::IEEEhalf()) &&
169 "Unexpected semantics");
170
171 // Handle the minimum normalized value which is different for each type.
172 if (FPImm.isSmallestNormalized() && !FPImm.isNegative())
173 return 1;
174
175 // Convert to single precision to use its lookup table.
176 bool LosesInfo;
177 APFloat::opStatus Status = FPImm.convert(
178 ToSemantics: APFloat::IEEEsingle(), RM: APFloat::rmNearestTiesToEven, losesInfo: &LosesInfo);
179 if (Status != APFloat::opOK || LosesInfo)
180 return -1;
181
182 APInt Imm = FPImm.bitcastToAPInt();
183
184 if (Imm.extractBitsAsZExtValue(numBits: 21, bitPosition: 0) != 0)
185 return -1;
186
187 bool Sign = Imm.extractBitsAsZExtValue(numBits: 1, bitPosition: 31);
188 uint8_t Mantissa = Imm.extractBitsAsZExtValue(numBits: 2, bitPosition: 21);
189 uint8_t Exp = Imm.extractBitsAsZExtValue(numBits: 8, bitPosition: 23);
190
191 auto EMI = llvm::lower_bound(Range: LoadFP32ImmArr, Value: std::make_pair(x&: Exp, y&: Mantissa));
192 if (EMI == std::end(arr: LoadFP32ImmArr) || EMI->first != Exp ||
193 EMI->second != Mantissa)
194 return -1;
195
196 // Table doesn't have entry 0 or 1.
197 int Entry = std::distance(first: std::begin(arr: LoadFP32ImmArr), last: EMI) + 2;
198
199 // The only legal negative value is -1.0(entry 0). 1.0 is entry 16.
200 if (Sign) {
201 if (Entry == 16)
202 return 0;
203 return -1;
204 }
205
206 return Entry;
207}
208
209float RISCVLoadFPImm::getFPImm(unsigned Imm) {
210 assert(Imm != 1 && Imm != 30 && Imm != 31 && "Unsupported immediate");
211
212 // Entry 0 is -1.0, the only negative value. Entry 16 is 1.0.
213 uint32_t Sign = 0;
214 if (Imm == 0) {
215 Sign = 0b1;
216 Imm = 16;
217 }
218
219 uint32_t Exp = LoadFP32ImmArr[Imm - 2].first;
220 uint32_t Mantissa = LoadFP32ImmArr[Imm - 2].second;
221
222 uint32_t I = Sign << 31 | Exp << 23 | Mantissa << 21;
223 return bit_cast<float>(from: I);
224}
225
226void RISCVZC::printRlist(unsigned SlistEncode, raw_ostream &OS) {
227 OS << "{ra";
228 if (SlistEncode > 4) {
229 OS << ", s0";
230 if (SlistEncode == 15)
231 OS << "-s11";
232 else if (SlistEncode > 5 && SlistEncode <= 14)
233 OS << "-s" << (SlistEncode - 5);
234 }
235 OS << "}";
236}
237
238} // namespace llvm
239