1//===-- SystemZMCAsmBackend.cpp - SystemZ assembler backend ---------------===//
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#include "MCTargetDesc/SystemZMCFixups.h"
10#include "MCTargetDesc/SystemZMCTargetDesc.h"
11#include "llvm/ADT/StringSwitch.h"
12#include "llvm/MC/MCAsmBackend.h"
13#include "llvm/MC/MCAssembler.h"
14#include "llvm/MC/MCContext.h"
15#include "llvm/MC/MCELFObjectWriter.h"
16#include "llvm/MC/MCInst.h"
17#include "llvm/MC/MCObjectWriter.h"
18#include "llvm/MC/MCSubtargetInfo.h"
19#include "llvm/MC/MCValue.h"
20
21using namespace llvm;
22
23// Value is a fully-resolved relocation value: Symbol + Addend [- Pivot].
24// Return the bits that should be installed in a relocation field for
25// fixup kind Kind.
26static uint64_t extractBitsForFixup(MCFixupKind Kind, uint64_t Value,
27 const MCFixup &Fixup, MCContext &Ctx) {
28 if (Kind < FirstTargetFixupKind)
29 return Value;
30
31 auto checkFixupInRange = [&](int64_t Min, int64_t Max) -> bool {
32 int64_t SVal = int64_t(Value);
33 if (SVal < Min || SVal > Max) {
34 Ctx.reportError(L: Fixup.getLoc(), Msg: "operand out of range (" + Twine(SVal) +
35 " not between " + Twine(Min) +
36 " and " + Twine(Max) + ")");
37 return false;
38 }
39 return true;
40 };
41
42 auto handlePCRelFixupValue = [&](unsigned W) -> uint64_t {
43 if (Value % 2 != 0)
44 Ctx.reportError(L: Fixup.getLoc(), Msg: "Non-even PC relative offset.");
45 if (!checkFixupInRange(minIntN(N: W) * 2, maxIntN(N: W) * 2))
46 return 0;
47 return (int64_t)Value / 2;
48 };
49
50 auto handleImmValue = [&](bool IsSigned, unsigned W) -> uint64_t {
51 if (!(IsSigned ? checkFixupInRange(minIntN(N: W), maxIntN(N: W))
52 : checkFixupInRange(0, maxUIntN(N: W))))
53 return 0;
54 return Value;
55 };
56
57 switch (unsigned(Kind)) {
58 case SystemZ::FK_390_PC12DBL:
59 return handlePCRelFixupValue(12);
60 case SystemZ::FK_390_PC16DBL:
61 return handlePCRelFixupValue(16);
62 case SystemZ::FK_390_PC24DBL:
63 return handlePCRelFixupValue(24);
64 case SystemZ::FK_390_PC32DBL:
65 return handlePCRelFixupValue(32);
66
67 case SystemZ::FK_390_TLS_CALL:
68 return 0;
69
70 case SystemZ::FK_390_S8Imm:
71 return handleImmValue(true, 8);
72 case SystemZ::FK_390_S16Imm:
73 return handleImmValue(true, 16);
74 case SystemZ::FK_390_S20Imm: {
75 Value = handleImmValue(true, 20);
76 // S20Imm is used only for signed 20-bit displacements.
77 // The high byte of a 20 bit displacement value comes first.
78 uint64_t DLo = Value & 0xfff;
79 uint64_t DHi = (Value >> 12) & 0xff;
80 return (DLo << 8) | DHi;
81 }
82 case SystemZ::FK_390_S32Imm:
83 return handleImmValue(true, 32);
84 case SystemZ::FK_390_U1Imm:
85 return handleImmValue(false, 1);
86 case SystemZ::FK_390_U2Imm:
87 return handleImmValue(false, 2);
88 case SystemZ::FK_390_U3Imm:
89 return handleImmValue(false, 3);
90 case SystemZ::FK_390_U4Imm:
91 return handleImmValue(false, 4);
92 case SystemZ::FK_390_U8Imm:
93 return handleImmValue(false, 8);
94 case SystemZ::FK_390_U12Imm:
95 return handleImmValue(false, 12);
96 case SystemZ::FK_390_U16Imm:
97 return handleImmValue(false, 16);
98 case SystemZ::FK_390_U32Imm:
99 return handleImmValue(false, 32);
100 case SystemZ::FK_390_U48Imm:
101 return handleImmValue(false, 48);
102 }
103
104 llvm_unreachable("Unknown fixup kind!");
105}
106
107namespace {
108class SystemZMCAsmBackend : public MCAsmBackend {
109public:
110 SystemZMCAsmBackend() : MCAsmBackend(llvm::endianness::big) {}
111
112 // Override MCAsmBackend
113 std::optional<MCFixupKind> getFixupKind(StringRef Name) const override;
114 MCFixupKindInfo getFixupKindInfo(MCFixupKind Kind) const override;
115 void applyFixup(const MCFragment &, const MCFixup &, const MCValue &Target,
116 uint8_t *Data, uint64_t Value, bool IsResolved) override;
117 bool writeNopData(raw_ostream &OS, uint64_t Count,
118 const MCSubtargetInfo *STI) const override;
119};
120} // end anonymous namespace
121
122std::optional<MCFixupKind>
123SystemZMCAsmBackend::getFixupKind(StringRef Name) const {
124 unsigned Type = llvm::StringSwitch<unsigned>(Name)
125#define ELF_RELOC(X, Y) .Case(#X, Y)
126#include "llvm/BinaryFormat/ELFRelocs/SystemZ.def"
127#undef ELF_RELOC
128 .Case(S: "BFD_RELOC_NONE", Value: ELF::R_390_NONE)
129 .Case(S: "BFD_RELOC_8", Value: ELF::R_390_8)
130 .Case(S: "BFD_RELOC_16", Value: ELF::R_390_16)
131 .Case(S: "BFD_RELOC_32", Value: ELF::R_390_32)
132 .Case(S: "BFD_RELOC_64", Value: ELF::R_390_64)
133 .Default(Value: -1u);
134 if (Type != -1u)
135 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type);
136 return std::nullopt;
137}
138
139MCFixupKindInfo SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
140 // Fixup kinds from .reloc directive are like R_390_NONE. They
141 // do not require any extra processing.
142 if (mc::isRelocation(FixupKind: Kind))
143 return {};
144
145 if (Kind < FirstTargetFixupKind)
146 return MCAsmBackend::getFixupKindInfo(Kind);
147
148 assert(unsigned(Kind - FirstTargetFixupKind) < SystemZ::NumTargetFixupKinds &&
149 "Invalid kind!");
150 return SystemZ::MCFixupKindInfos[Kind - FirstTargetFixupKind];
151}
152
153void SystemZMCAsmBackend::applyFixup(const MCFragment &F, const MCFixup &Fixup,
154 const MCValue &Target, uint8_t *Data,
155 uint64_t Value, bool IsResolved) {
156 if (Target.getSpecifier())
157 IsResolved = false;
158 maybeAddReloc(F, Fixup, Target, Value, IsResolved);
159 MCFixupKind Kind = Fixup.getKind();
160 if (mc::isRelocation(FixupKind: Kind))
161 return;
162 unsigned BitSize = getFixupKindInfo(Kind).TargetSize;
163 unsigned Size = (BitSize + 7) / 8;
164
165 assert(Fixup.getOffset() + Size <= F.getSize() && "Invalid fixup offset!");
166
167 // Big-endian insertion of Size bytes.
168 Value = extractBitsForFixup(Kind, Value, Fixup, Ctx&: getContext());
169 if (BitSize < 64)
170 Value &= ((uint64_t)1 << BitSize) - 1;
171 unsigned ShiftValue = (Size * 8) - 8;
172 for (unsigned I = 0; I != Size; ++I) {
173 Data[I] |= uint8_t(Value >> ShiftValue);
174 ShiftValue -= 8;
175 }
176}
177
178bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
179 const MCSubtargetInfo *STI) const {
180 for (uint64_t I = 0; I != Count; ++I)
181 OS << '\x7';
182 return true;
183}
184
185namespace {
186class ELFSystemZAsmBackend : public SystemZMCAsmBackend {
187 uint8_t OSABI;
188
189public:
190 ELFSystemZAsmBackend(uint8_t OsABI) : SystemZMCAsmBackend(), OSABI(OsABI){};
191
192 std::unique_ptr<MCObjectTargetWriter>
193 createObjectTargetWriter() const override {
194 return createSystemZELFObjectWriter(OSABI);
195 }
196};
197
198class GOFFSystemZAsmBackend : public SystemZMCAsmBackend {
199public:
200 GOFFSystemZAsmBackend() : SystemZMCAsmBackend(){};
201
202 std::unique_ptr<MCObjectTargetWriter>
203 createObjectTargetWriter() const override {
204 return createSystemZGOFFObjectWriter();
205 }
206};
207} // namespace
208
209MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T,
210 const MCSubtargetInfo &STI,
211 const MCRegisterInfo &MRI,
212 const MCTargetOptions &Options) {
213 if (STI.getTargetTriple().isOSzOS()) {
214 return new GOFFSystemZAsmBackend();
215 }
216
217 uint8_t OSABI =
218 MCELFObjectTargetWriter::getOSABI(OSType: STI.getTargetTriple().getOS());
219 return new ELFSystemZAsmBackend(OSABI);
220}
221