1 //===-- MBlazeAsmBackend.cpp - MBlaze Assembler Backend -------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "MCTargetDesc/MBlazeMCTargetDesc.h"
11 #include "llvm/MC/MCAsmBackend.h"
12 #include "llvm/MC/MCAssembler.h"
13 #include "llvm/MC/MCAsmLayout.h"
14 #include "llvm/MC/MCELFObjectWriter.h"
15 #include "llvm/MC/MCELFSymbolFlags.h"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCObjectWriter.h"
18 #include "llvm/MC/MCSectionELF.h"
19 #include "llvm/MC/MCSectionMachO.h"
20 #include "llvm/MC/MCValue.h"
21 #include "llvm/ADT/Twine.h"
22 #include "llvm/Support/ELF.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/TargetRegistry.h"
25 #include "llvm/Support/raw_ostream.h"
26 using namespace llvm;
27
getFixupKindSize(unsigned Kind)28 static unsigned getFixupKindSize(unsigned Kind) {
29 switch (Kind) {
30 default: llvm_unreachable("invalid fixup kind!");
31 case FK_Data_1: return 1;
32 case FK_PCRel_2:
33 case FK_Data_2: return 2;
34 case FK_PCRel_4:
35 case FK_Data_4: return 4;
36 case FK_Data_8: return 8;
37 }
38 }
39
40
41 namespace {
42
43 class MBlazeAsmBackend : public MCAsmBackend {
44 public:
MBlazeAsmBackend(const Target & T)45 MBlazeAsmBackend(const Target &T)
46 : MCAsmBackend() {
47 }
48
getNumFixupKinds() const49 unsigned getNumFixupKinds() const {
50 return 2;
51 }
52
53 bool mayNeedRelaxation(const MCInst &Inst) const;
54
55 bool fixupNeedsRelaxation(const MCFixup &Fixup,
56 uint64_t Value,
57 const MCInstFragment *DF,
58 const MCAsmLayout &Layout) const;
59
60 void relaxInstruction(const MCInst &Inst, MCInst &Res) const;
61
62 bool writeNopData(uint64_t Count, MCObjectWriter *OW) const;
63
getPointerSize() const64 unsigned getPointerSize() const {
65 return 4;
66 }
67 };
68
getRelaxedOpcode(unsigned Op)69 static unsigned getRelaxedOpcode(unsigned Op) {
70 switch (Op) {
71 default: return Op;
72 case MBlaze::ADDIK: return MBlaze::ADDIK32;
73 case MBlaze::ORI: return MBlaze::ORI32;
74 case MBlaze::BRLID: return MBlaze::BRLID32;
75 }
76 }
77
mayNeedRelaxation(const MCInst & Inst) const78 bool MBlazeAsmBackend::mayNeedRelaxation(const MCInst &Inst) const {
79 if (getRelaxedOpcode(Inst.getOpcode()) == Inst.getOpcode())
80 return false;
81
82 bool hasExprOrImm = false;
83 for (unsigned i = 0; i < Inst.getNumOperands(); ++i)
84 hasExprOrImm |= Inst.getOperand(i).isExpr();
85
86 return hasExprOrImm;
87 }
88
fixupNeedsRelaxation(const MCFixup & Fixup,uint64_t Value,const MCInstFragment * DF,const MCAsmLayout & Layout) const89 bool MBlazeAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup,
90 uint64_t Value,
91 const MCInstFragment *DF,
92 const MCAsmLayout &Layout) const {
93 // FIXME: Is this right? It's what the "generic" code was doing before,
94 // but is X86 specific. Is it actually true for MBlaze also, or was it
95 // just close enough to not be a big deal?
96 //
97 // Relax if the value is too big for a (signed) i8.
98 return int64_t(Value) != int64_t(int8_t(Value));
99 }
100
relaxInstruction(const MCInst & Inst,MCInst & Res) const101 void MBlazeAsmBackend::relaxInstruction(const MCInst &Inst, MCInst &Res) const {
102 Res = Inst;
103 Res.setOpcode(getRelaxedOpcode(Inst.getOpcode()));
104 }
105
writeNopData(uint64_t Count,MCObjectWriter * OW) const106 bool MBlazeAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
107 if ((Count % 4) != 0)
108 return false;
109
110 for (uint64_t i = 0; i < Count; i += 4)
111 OW->Write32(0x00000000);
112
113 return true;
114 }
115 } // end anonymous namespace
116
117 namespace {
118 class ELFMBlazeAsmBackend : public MBlazeAsmBackend {
119 public:
120 uint8_t OSABI;
ELFMBlazeAsmBackend(const Target & T,uint8_t _OSABI)121 ELFMBlazeAsmBackend(const Target &T, uint8_t _OSABI)
122 : MBlazeAsmBackend(T), OSABI(_OSABI) { }
123
124 void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
125 uint64_t Value) const;
126
createObjectWriter(raw_ostream & OS) const127 MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
128 return createMBlazeELFObjectWriter(OS, OSABI);
129 }
130 };
131
applyFixup(const MCFixup & Fixup,char * Data,unsigned DataSize,uint64_t Value) const132 void ELFMBlazeAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
133 unsigned DataSize, uint64_t Value) const {
134 unsigned Size = getFixupKindSize(Fixup.getKind());
135
136 assert(Fixup.getOffset() + Size <= DataSize &&
137 "Invalid fixup offset!");
138
139 char *data = Data + Fixup.getOffset();
140 switch (Size) {
141 default: llvm_unreachable("Cannot fixup unknown value.");
142 case 1: llvm_unreachable("Cannot fixup 1 byte value.");
143 case 8: llvm_unreachable("Cannot fixup 8 byte value.");
144
145 case 4:
146 *(data+7) = uint8_t(Value);
147 *(data+6) = uint8_t(Value >> 8);
148 *(data+3) = uint8_t(Value >> 16);
149 *(data+2) = uint8_t(Value >> 24);
150 break;
151
152 case 2:
153 *(data+3) = uint8_t(Value >> 0);
154 *(data+2) = uint8_t(Value >> 8);
155 }
156 }
157 } // end anonymous namespace
158
createMBlazeAsmBackend(const Target & T,StringRef TT)159 MCAsmBackend *llvm::createMBlazeAsmBackend(const Target &T, StringRef TT) {
160 Triple TheTriple(TT);
161
162 if (TheTriple.isOSDarwin())
163 assert(0 && "Mac not supported on MBlaze");
164
165 if (TheTriple.isOSWindows())
166 assert(0 && "Windows not supported on MBlaze");
167
168 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TheTriple.getOS());
169 return new ELFMBlazeAsmBackend(T, OSABI);
170 }
171