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/MC/MCAsmBackend.h"
12 #include "llvm/MC/MCELFObjectWriter.h"
13 #include "llvm/MC/MCFixupKindInfo.h"
14 #include "llvm/MC/MCInst.h"
15 #include "llvm/MC/MCObjectWriter.h"
16 #include "llvm/MC/MCSubtargetInfo.h"
17
18 using namespace llvm;
19
20 // Value is a fully-resolved relocation value: Symbol + Addend [- Pivot].
21 // Return the bits that should be installed in a relocation field for
22 // fixup kind Kind.
extractBitsForFixup(MCFixupKind Kind,uint64_t Value)23 static uint64_t extractBitsForFixup(MCFixupKind Kind, uint64_t Value) {
24 if (Kind < FirstTargetFixupKind)
25 return Value;
26
27 switch (unsigned(Kind)) {
28 case SystemZ::FK_390_PC12DBL:
29 case SystemZ::FK_390_PC16DBL:
30 case SystemZ::FK_390_PC24DBL:
31 case SystemZ::FK_390_PC32DBL:
32 return (int64_t)Value / 2;
33
34 case SystemZ::FK_390_TLS_CALL:
35 return 0;
36 }
37
38 llvm_unreachable("Unknown fixup kind!");
39 }
40
41 namespace {
42 class SystemZMCAsmBackend : public MCAsmBackend {
43 uint8_t OSABI;
44 public:
SystemZMCAsmBackend(uint8_t osABI)45 SystemZMCAsmBackend(uint8_t osABI)
46 : MCAsmBackend(support::big), OSABI(osABI) {}
47
48 // Override MCAsmBackend
getNumFixupKinds() const49 unsigned getNumFixupKinds() const override {
50 return SystemZ::NumTargetFixupKinds;
51 }
52 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
53 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
54 const MCValue &Target, MutableArrayRef<char> Data,
55 uint64_t Value, bool IsResolved,
56 const MCSubtargetInfo *STI) const override;
mayNeedRelaxation(const MCInst & Inst,const MCSubtargetInfo & STI) const57 bool mayNeedRelaxation(const MCInst &Inst,
58 const MCSubtargetInfo &STI) const override {
59 return false;
60 }
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 }
relaxInstruction(const MCInst & Inst,const MCSubtargetInfo & STI,MCInst & Res) const66 void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
67 MCInst &Res) const override {
68 llvm_unreachable("SystemZ does do not have assembler relaxation");
69 }
70 bool writeNopData(raw_ostream &OS, uint64_t Count) const override;
71 std::unique_ptr<MCObjectTargetWriter>
createObjectTargetWriter() const72 createObjectTargetWriter() const override {
73 return createSystemZObjectWriter(OSABI);
74 }
75 };
76 } // end anonymous namespace
77
78 const MCFixupKindInfo &
getFixupKindInfo(MCFixupKind Kind) const79 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
80 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = {
81 { "FK_390_PC12DBL", 4, 12, MCFixupKindInfo::FKF_IsPCRel },
82 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
83 { "FK_390_PC24DBL", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
84 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
85 { "FK_390_TLS_CALL", 0, 0, 0 }
86 };
87
88 if (Kind < FirstTargetFixupKind)
89 return MCAsmBackend::getFixupKindInfo(Kind);
90
91 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
92 "Invalid kind!");
93 return Infos[Kind - FirstTargetFixupKind];
94 }
95
applyFixup(const MCAssembler & Asm,const MCFixup & Fixup,const MCValue & Target,MutableArrayRef<char> Data,uint64_t Value,bool IsResolved,const MCSubtargetInfo * STI) const96 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm,
97 const MCFixup &Fixup,
98 const MCValue &Target,
99 MutableArrayRef<char> Data, uint64_t Value,
100 bool IsResolved,
101 const MCSubtargetInfo *STI) const {
102 MCFixupKind Kind = Fixup.getKind();
103 unsigned Offset = Fixup.getOffset();
104 unsigned BitSize = getFixupKindInfo(Kind).TargetSize;
105 unsigned Size = (BitSize + 7) / 8;
106
107 assert(Offset + Size <= Data.size() && "Invalid fixup offset!");
108
109 // Big-endian insertion of Size bytes.
110 Value = extractBitsForFixup(Kind, Value);
111 if (BitSize < 64)
112 Value &= ((uint64_t)1 << BitSize) - 1;
113 unsigned ShiftValue = (Size * 8) - 8;
114 for (unsigned I = 0; I != Size; ++I) {
115 Data[Offset + I] |= uint8_t(Value >> ShiftValue);
116 ShiftValue -= 8;
117 }
118 }
119
writeNopData(raw_ostream & OS,uint64_t Count) const120 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
121 for (uint64_t I = 0; I != Count; ++I)
122 OS << '\x7';
123 return true;
124 }
125
createSystemZMCAsmBackend(const Target & T,const MCSubtargetInfo & STI,const MCRegisterInfo & MRI,const MCTargetOptions & Options)126 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T,
127 const MCSubtargetInfo &STI,
128 const MCRegisterInfo &MRI,
129 const MCTargetOptions &Options) {
130 uint8_t OSABI =
131 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS());
132 return new SystemZMCAsmBackend(OSABI);
133 }
134