1 //===-- LanaiAsmBackend.cpp - Lanai 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 "LanaiFixupKinds.h"
10 #include "MCTargetDesc/LanaiMCTargetDesc.h"
11 #include "llvm/MC/MCAsmBackend.h"
12 #include "llvm/MC/MCAssembler.h"
13 #include "llvm/MC/MCDirectives.h"
14 #include "llvm/MC/MCELFObjectWriter.h"
15 #include "llvm/MC/MCFixupKindInfo.h"
16 #include "llvm/MC/MCObjectWriter.h"
17 #include "llvm/MC/MCSubtargetInfo.h"
18 #include "llvm/Support/ErrorHandling.h"
19 #include "llvm/Support/raw_ostream.h"
20
21 using namespace llvm;
22
23 // Prepare value for the target space
adjustFixupValue(unsigned Kind,uint64_t Value)24 static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
25 switch (Kind) {
26 case FK_Data_1:
27 case FK_Data_2:
28 case FK_Data_4:
29 case FK_Data_8:
30 return Value;
31 case Lanai::FIXUP_LANAI_21:
32 case Lanai::FIXUP_LANAI_21_F:
33 case Lanai::FIXUP_LANAI_25:
34 case Lanai::FIXUP_LANAI_32:
35 case Lanai::FIXUP_LANAI_HI16:
36 case Lanai::FIXUP_LANAI_LO16:
37 return Value;
38 default:
39 llvm_unreachable("Unknown fixup kind!");
40 }
41 }
42
43 namespace {
44 class LanaiAsmBackend : public MCAsmBackend {
45 Triple::OSType OSType;
46
47 public:
LanaiAsmBackend(const Target & T,Triple::OSType OST)48 LanaiAsmBackend(const Target &T, Triple::OSType OST)
49 : MCAsmBackend(llvm::endianness::big), OSType(OST) {}
50
51 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
52 const MCValue &Target, MutableArrayRef<char> Data,
53 uint64_t Value, bool IsResolved,
54 const MCSubtargetInfo *STI) const override;
55
56 std::unique_ptr<MCObjectTargetWriter>
57 createObjectTargetWriter() const override;
58
59 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
60
getNumFixupKinds() const61 unsigned getNumFixupKinds() const override {
62 return Lanai::NumTargetFixupKinds;
63 }
64
65 bool writeNopData(raw_ostream &OS, uint64_t Count,
66 const MCSubtargetInfo *STI) const override;
67 };
68
writeNopData(raw_ostream & OS,uint64_t Count,const MCSubtargetInfo * STI) const69 bool LanaiAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
70 const MCSubtargetInfo *STI) const {
71 if ((Count % 4) != 0)
72 return false;
73
74 for (uint64_t i = 0; i < Count; i += 4)
75 OS.write("\x15\0\0\0", 4);
76
77 return true;
78 }
79
applyFixup(const MCAssembler & Asm,const MCFixup & Fixup,const MCValue & Target,MutableArrayRef<char> Data,uint64_t Value,bool,const MCSubtargetInfo *) const80 void LanaiAsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
81 const MCValue &Target,
82 MutableArrayRef<char> Data, uint64_t Value,
83 bool /*IsResolved*/,
84 const MCSubtargetInfo * /*STI*/) const {
85 MCFixupKind Kind = Fixup.getKind();
86 Value = adjustFixupValue(static_cast<unsigned>(Kind), Value);
87
88 if (!Value)
89 return; // This value doesn't change the encoding
90
91 // Where in the object and where the number of bytes that need
92 // fixing up
93 unsigned Offset = Fixup.getOffset();
94 unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8;
95 unsigned FullSize = 4;
96
97 // Grab current value, if any, from bits.
98 uint64_t CurVal = 0;
99
100 // Load instruction and apply value
101 for (unsigned i = 0; i != NumBytes; ++i) {
102 unsigned Idx = (FullSize - 1 - i);
103 CurVal |= static_cast<uint64_t>(static_cast<uint8_t>(Data[Offset + Idx]))
104 << (i * 8);
105 }
106
107 uint64_t Mask =
108 (static_cast<uint64_t>(-1) >> (64 - getFixupKindInfo(Kind).TargetSize));
109 CurVal |= Value & Mask;
110
111 // Write out the fixed up bytes back to the code/data bits.
112 for (unsigned i = 0; i != NumBytes; ++i) {
113 unsigned Idx = (FullSize - 1 - i);
114 Data[Offset + Idx] = static_cast<uint8_t>((CurVal >> (i * 8)) & 0xff);
115 }
116 }
117
118 std::unique_ptr<MCObjectTargetWriter>
createObjectTargetWriter() const119 LanaiAsmBackend::createObjectTargetWriter() const {
120 return createLanaiELFObjectWriter(MCELFObjectTargetWriter::getOSABI(OSType));
121 }
122
123 const MCFixupKindInfo &
getFixupKindInfo(MCFixupKind Kind) const124 LanaiAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
125 static const MCFixupKindInfo Infos[Lanai::NumTargetFixupKinds] = {
126 // This table *must* be in same the order of fixup_* kinds in
127 // LanaiFixupKinds.h.
128 // Note: The number of bits indicated here are assumed to be contiguous.
129 // This does not hold true for LANAI_21 and LANAI_21_F which are applied
130 // to bits 0x7cffff and 0x7cfffc, respectively. Since the 'bits' counts
131 // here are used only for cosmetic purposes, we set the size to 16 bits
132 // for these 21-bit relocation as llvm/lib/MC/MCAsmStreamer.cpp checks
133 // no bits are set in the fixup range.
134 //
135 // name offset bits flags
136 {"FIXUP_LANAI_NONE", 0, 32, 0},
137 {"FIXUP_LANAI_21", 16, 16 /*21*/, 0},
138 {"FIXUP_LANAI_21_F", 16, 16 /*21*/, 0},
139 {"FIXUP_LANAI_25", 7, 25, 0},
140 {"FIXUP_LANAI_32", 0, 32, 0},
141 {"FIXUP_LANAI_HI16", 16, 16, 0},
142 {"FIXUP_LANAI_LO16", 16, 16, 0}};
143
144 if (Kind < FirstTargetFixupKind)
145 return MCAsmBackend::getFixupKindInfo(Kind);
146
147 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
148 "Invalid kind!");
149 return Infos[Kind - FirstTargetFixupKind];
150 }
151
152 } // namespace
153
createLanaiAsmBackend(const Target & T,const MCSubtargetInfo & STI,const MCRegisterInfo &,const MCTargetOptions &)154 MCAsmBackend *llvm::createLanaiAsmBackend(const Target &T,
155 const MCSubtargetInfo &STI,
156 const MCRegisterInfo & /*MRI*/,
157 const MCTargetOptions & /*Options*/) {
158 const Triple &TT = STI.getTargetTriple();
159 if (!TT.isOSBinFormatELF())
160 llvm_unreachable("OS not supported");
161
162 return new LanaiAsmBackend(T, TT.getOS());
163 }
164