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/MCELFObjectWriter.h"
14 #include "llvm/MC/MCFixupKindInfo.h"
15 #include "llvm/MC/MCInst.h"
16 #include "llvm/MC/MCObjectWriter.h"
17 #include "llvm/MC/MCSubtargetInfo.h"
18
19 using namespace llvm;
20
21 // Value is a fully-resolved relocation value: Symbol + Addend [- Pivot].
22 // Return the bits that should be installed in a relocation field for
23 // fixup kind Kind.
extractBitsForFixup(MCFixupKind Kind,uint64_t Value)24 static uint64_t extractBitsForFixup(MCFixupKind Kind, uint64_t Value) {
25 if (Kind < FirstTargetFixupKind)
26 return Value;
27
28 switch (unsigned(Kind)) {
29 case SystemZ::FK_390_PC12DBL:
30 case SystemZ::FK_390_PC16DBL:
31 case SystemZ::FK_390_PC24DBL:
32 case SystemZ::FK_390_PC32DBL:
33 return (int64_t)Value / 2;
34
35 case SystemZ::FK_390_TLS_CALL:
36 return 0;
37 }
38
39 llvm_unreachable("Unknown fixup kind!");
40 }
41
42 namespace {
43 class SystemZMCAsmBackend : public MCAsmBackend {
44 uint8_t OSABI;
45 public:
SystemZMCAsmBackend(uint8_t osABI)46 SystemZMCAsmBackend(uint8_t osABI)
47 : MCAsmBackend(support::big), OSABI(osABI) {}
48
49 // Override MCAsmBackend
getNumFixupKinds() const50 unsigned getNumFixupKinds() const override {
51 return SystemZ::NumTargetFixupKinds;
52 }
53 Optional<MCFixupKind> getFixupKind(StringRef Name) const override;
54 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
55 bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup,
56 const MCValue &Target) override;
57 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
58 const MCValue &Target, MutableArrayRef<char> Data,
59 uint64_t Value, bool IsResolved,
60 const MCSubtargetInfo *STI) const override;
fixupNeedsRelaxation(const MCFixup & Fixup,uint64_t Value,const MCRelaxableFragment * Fragment,const MCAsmLayout & Layout) const61 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
62 const MCRelaxableFragment *Fragment,
63 const MCAsmLayout &Layout) const override {
64 return false;
65 }
66 bool writeNopData(raw_ostream &OS, uint64_t Count) const override;
67 std::unique_ptr<MCObjectTargetWriter>
createObjectTargetWriter() const68 createObjectTargetWriter() const override {
69 return createSystemZObjectWriter(OSABI);
70 }
71 };
72 } // end anonymous namespace
73
getFixupKind(StringRef Name) const74 Optional<MCFixupKind> SystemZMCAsmBackend::getFixupKind(StringRef Name) const {
75 unsigned Type = llvm::StringSwitch<unsigned>(Name)
76 #define ELF_RELOC(X, Y) .Case(#X, Y)
77 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def"
78 #undef ELF_RELOC
79 .Case("BFD_RELOC_NONE", ELF::R_390_NONE)
80 .Case("BFD_RELOC_8", ELF::R_390_8)
81 .Case("BFD_RELOC_16", ELF::R_390_16)
82 .Case("BFD_RELOC_32", ELF::R_390_32)
83 .Case("BFD_RELOC_64", ELF::R_390_64)
84 .Default(-1u);
85 if (Type != -1u)
86 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type);
87 return None;
88 }
89
90 const MCFixupKindInfo &
getFixupKindInfo(MCFixupKind Kind) const91 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
92 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = {
93 { "FK_390_PC12DBL", 4, 12, MCFixupKindInfo::FKF_IsPCRel },
94 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
95 { "FK_390_PC24DBL", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
96 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
97 { "FK_390_TLS_CALL", 0, 0, 0 }
98 };
99
100 // Fixup kinds from .reloc directive are like R_390_NONE. They
101 // do not require any extra processing.
102 if (Kind >= FirstLiteralRelocationKind)
103 return MCAsmBackend::getFixupKindInfo(FK_NONE);
104
105 if (Kind < FirstTargetFixupKind)
106 return MCAsmBackend::getFixupKindInfo(Kind);
107
108 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
109 "Invalid kind!");
110 return Infos[Kind - FirstTargetFixupKind];
111 }
112
shouldForceRelocation(const MCAssembler &,const MCFixup & Fixup,const MCValue &)113 bool SystemZMCAsmBackend::shouldForceRelocation(const MCAssembler &,
114 const MCFixup &Fixup,
115 const MCValue &) {
116 return Fixup.getKind() >= FirstLiteralRelocationKind;
117 }
118
applyFixup(const MCAssembler & Asm,const MCFixup & Fixup,const MCValue & Target,MutableArrayRef<char> Data,uint64_t Value,bool IsResolved,const MCSubtargetInfo * STI) const119 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm,
120 const MCFixup &Fixup,
121 const MCValue &Target,
122 MutableArrayRef<char> Data, uint64_t Value,
123 bool IsResolved,
124 const MCSubtargetInfo *STI) const {
125 MCFixupKind Kind = Fixup.getKind();
126 if (Kind >= FirstLiteralRelocationKind)
127 return;
128 unsigned Offset = Fixup.getOffset();
129 unsigned BitSize = getFixupKindInfo(Kind).TargetSize;
130 unsigned Size = (BitSize + 7) / 8;
131
132 assert(Offset + Size <= Data.size() && "Invalid fixup offset!");
133
134 // Big-endian insertion of Size bytes.
135 Value = extractBitsForFixup(Kind, Value);
136 if (BitSize < 64)
137 Value &= ((uint64_t)1 << BitSize) - 1;
138 unsigned ShiftValue = (Size * 8) - 8;
139 for (unsigned I = 0; I != Size; ++I) {
140 Data[Offset + I] |= uint8_t(Value >> ShiftValue);
141 ShiftValue -= 8;
142 }
143 }
144
writeNopData(raw_ostream & OS,uint64_t Count) const145 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
146 for (uint64_t I = 0; I != Count; ++I)
147 OS << '\x7';
148 return true;
149 }
150
createSystemZMCAsmBackend(const Target & T,const MCSubtargetInfo & STI,const MCRegisterInfo & MRI,const MCTargetOptions & Options)151 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T,
152 const MCSubtargetInfo &STI,
153 const MCRegisterInfo &MRI,
154 const MCTargetOptions &Options) {
155 uint8_t OSABI =
156 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS());
157 return new SystemZMCAsmBackend(OSABI);
158 }
159