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;
fixupNeedsRelaxation(const MCFixup & Fixup,uint64_t Value,const MCRelaxableFragment * Fragment,const MCAsmLayout & Layout) const57 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
58 const MCRelaxableFragment *Fragment,
59 const MCAsmLayout &Layout) const override {
60 return false;
61 }
62 bool writeNopData(raw_ostream &OS, uint64_t Count) const override;
63 std::unique_ptr<MCObjectTargetWriter>
createObjectTargetWriter() const64 createObjectTargetWriter() const override {
65 return createSystemZObjectWriter(OSABI);
66 }
67 };
68 } // end anonymous namespace
69
70 const MCFixupKindInfo &
getFixupKindInfo(MCFixupKind Kind) const71 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
72 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = {
73 { "FK_390_PC12DBL", 4, 12, MCFixupKindInfo::FKF_IsPCRel },
74 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
75 { "FK_390_PC24DBL", 0, 24, MCFixupKindInfo::FKF_IsPCRel },
76 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel },
77 { "FK_390_TLS_CALL", 0, 0, 0 }
78 };
79
80 if (Kind < FirstTargetFixupKind)
81 return MCAsmBackend::getFixupKindInfo(Kind);
82
83 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
84 "Invalid kind!");
85 return Infos[Kind - FirstTargetFixupKind];
86 }
87
applyFixup(const MCAssembler & Asm,const MCFixup & Fixup,const MCValue & Target,MutableArrayRef<char> Data,uint64_t Value,bool IsResolved,const MCSubtargetInfo * STI) const88 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm,
89 const MCFixup &Fixup,
90 const MCValue &Target,
91 MutableArrayRef<char> Data, uint64_t Value,
92 bool IsResolved,
93 const MCSubtargetInfo *STI) const {
94 MCFixupKind Kind = Fixup.getKind();
95 unsigned Offset = Fixup.getOffset();
96 unsigned BitSize = getFixupKindInfo(Kind).TargetSize;
97 unsigned Size = (BitSize + 7) / 8;
98
99 assert(Offset + Size <= Data.size() && "Invalid fixup offset!");
100
101 // Big-endian insertion of Size bytes.
102 Value = extractBitsForFixup(Kind, Value);
103 if (BitSize < 64)
104 Value &= ((uint64_t)1 << BitSize) - 1;
105 unsigned ShiftValue = (Size * 8) - 8;
106 for (unsigned I = 0; I != Size; ++I) {
107 Data[Offset + I] |= uint8_t(Value >> ShiftValue);
108 ShiftValue -= 8;
109 }
110 }
111
writeNopData(raw_ostream & OS,uint64_t Count) const112 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
113 for (uint64_t I = 0; I != Count; ++I)
114 OS << '\x7';
115 return true;
116 }
117
createSystemZMCAsmBackend(const Target & T,const MCSubtargetInfo & STI,const MCRegisterInfo & MRI,const MCTargetOptions & Options)118 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T,
119 const MCSubtargetInfo &STI,
120 const MCRegisterInfo &MRI,
121 const MCTargetOptions &Options) {
122 uint8_t OSABI =
123 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS());
124 return new SystemZMCAsmBackend(OSABI);
125 }
126