1 //===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
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 // This file implements the Dwarf emissions parts of AsmPrinter.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #define DEBUG_TYPE "asm-printer"
15 #include "llvm/CodeGen/AsmPrinter.h"
16 #include "llvm/MC/MachineLocation.h"
17 #include "llvm/MC/MCAsmInfo.h"
18 #include "llvm/MC/MCSection.h"
19 #include "llvm/MC/MCStreamer.h"
20 #include "llvm/MC/MCSymbol.h"
21 #include "llvm/Target/TargetData.h"
22 #include "llvm/Target/TargetFrameLowering.h"
23 #include "llvm/Target/TargetLoweringObjectFile.h"
24 #include "llvm/Target/TargetMachine.h"
25 #include "llvm/Target/TargetRegisterInfo.h"
26 #include "llvm/ADT/Twine.h"
27 #include "llvm/Support/Dwarf.h"
28 using namespace llvm;
29
30 //===----------------------------------------------------------------------===//
31 // Dwarf Emission Helper Routines
32 //===----------------------------------------------------------------------===//
33
34 /// EmitSLEB128 - emit the specified signed leb128 value.
EmitSLEB128(int Value,const char * Desc) const35 void AsmPrinter::EmitSLEB128(int Value, const char *Desc) const {
36 if (isVerbose() && Desc)
37 OutStreamer.AddComment(Desc);
38
39 if (MAI->hasLEB128()) {
40 OutStreamer.EmitSLEB128IntValue(Value);
41 return;
42 }
43
44 // If we don't have .sleb128, emit as .bytes.
45 int Sign = Value >> (8 * sizeof(Value) - 1);
46 bool IsMore;
47
48 do {
49 unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
50 Value >>= 7;
51 IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
52 if (IsMore) Byte |= 0x80;
53 OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
54 } while (IsMore);
55 }
56
57 /// EmitULEB128 - emit the specified signed leb128 value.
EmitULEB128(unsigned Value,const char * Desc,unsigned PadTo) const58 void AsmPrinter::EmitULEB128(unsigned Value, const char *Desc,
59 unsigned PadTo) const {
60 if (isVerbose() && Desc)
61 OutStreamer.AddComment(Desc);
62
63 // FIXME: Should we add a PadTo option to the streamer?
64 if (MAI->hasLEB128() && PadTo == 0) {
65 OutStreamer.EmitULEB128IntValue(Value);
66 return;
67 }
68
69 // If we don't have .uleb128 or we want to emit padding, emit as .bytes.
70 do {
71 unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
72 Value >>= 7;
73 if (Value || PadTo != 0) Byte |= 0x80;
74 OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
75 } while (Value);
76
77 if (PadTo) {
78 if (PadTo > 1)
79 OutStreamer.EmitFill(PadTo - 1, 0x80/*fillval*/, 0/*addrspace*/);
80 OutStreamer.EmitFill(1, 0/*fillval*/, 0/*addrspace*/);
81 }
82 }
83
84 /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
EmitCFAByte(unsigned Val) const85 void AsmPrinter::EmitCFAByte(unsigned Val) const {
86 if (isVerbose()) {
87 if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset+64)
88 OutStreamer.AddComment("DW_CFA_offset + Reg (" +
89 Twine(Val-dwarf::DW_CFA_offset) + ")");
90 else
91 OutStreamer.AddComment(dwarf::CallFrameString(Val));
92 }
93 OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
94 }
95
DecodeDWARFEncoding(unsigned Encoding)96 static const char *DecodeDWARFEncoding(unsigned Encoding) {
97 switch (Encoding) {
98 case dwarf::DW_EH_PE_absptr: return "absptr";
99 case dwarf::DW_EH_PE_omit: return "omit";
100 case dwarf::DW_EH_PE_pcrel: return "pcrel";
101 case dwarf::DW_EH_PE_udata4: return "udata4";
102 case dwarf::DW_EH_PE_udata8: return "udata8";
103 case dwarf::DW_EH_PE_sdata4: return "sdata4";
104 case dwarf::DW_EH_PE_sdata8: return "sdata8";
105 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: return "pcrel udata4";
106 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: return "pcrel sdata4";
107 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: return "pcrel udata8";
108 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: return "pcrel sdata8";
109 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata4:
110 return "indirect pcrel udata4";
111 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata4:
112 return "indirect pcrel sdata4";
113 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata8:
114 return "indirect pcrel udata8";
115 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata8:
116 return "indirect pcrel sdata8";
117 }
118
119 return "<unknown encoding>";
120 }
121
122
123 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
124 /// encoding. If verbose assembly output is enabled, we output comments
125 /// describing the encoding. Desc is an optional string saying what the
126 /// encoding is specifying (e.g. "LSDA").
EmitEncodingByte(unsigned Val,const char * Desc) const127 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
128 if (isVerbose()) {
129 if (Desc != 0)
130 OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
131 Twine(DecodeDWARFEncoding(Val)));
132 else
133 OutStreamer.AddComment(Twine("Encoding = ") +
134 DecodeDWARFEncoding(Val));
135 }
136
137 OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
138 }
139
140 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
GetSizeOfEncodedValue(unsigned Encoding) const141 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
142 if (Encoding == dwarf::DW_EH_PE_omit)
143 return 0;
144
145 switch (Encoding & 0x07) {
146 default: assert(0 && "Invalid encoded value.");
147 case dwarf::DW_EH_PE_absptr: return TM.getTargetData()->getPointerSize();
148 case dwarf::DW_EH_PE_udata2: return 2;
149 case dwarf::DW_EH_PE_udata4: return 4;
150 case dwarf::DW_EH_PE_udata8: return 8;
151 }
152 }
153
EmitReference(const MCSymbol * Sym,unsigned Encoding) const154 void AsmPrinter::EmitReference(const MCSymbol *Sym, unsigned Encoding) const {
155 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
156
157 const MCExpr *Exp =
158 TLOF.getExprForDwarfReference(Sym, Encoding, OutStreamer);
159 OutStreamer.EmitAbsValue(Exp, GetSizeOfEncodedValue(Encoding));
160 }
161
EmitReference(const GlobalValue * GV,unsigned Encoding) const162 void AsmPrinter::EmitReference(const GlobalValue *GV, unsigned Encoding)const{
163 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
164
165 const MCExpr *Exp =
166 TLOF.getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, OutStreamer);
167 OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding), /*addrspace*/0);
168 }
169
170 /// EmitSectionOffset - Emit the 4-byte offset of Label from the start of its
171 /// section. This can be done with a special directive if the target supports
172 /// it (e.g. cygwin) or by emitting it as an offset from a label at the start
173 /// of the section.
174 ///
175 /// SectionLabel is a temporary label emitted at the start of the section that
176 /// Label lives in.
EmitSectionOffset(const MCSymbol * Label,const MCSymbol * SectionLabel) const177 void AsmPrinter::EmitSectionOffset(const MCSymbol *Label,
178 const MCSymbol *SectionLabel) const {
179 // On COFF targets, we have to emit the special .secrel32 directive.
180 if (const char *SecOffDir = MAI->getDwarfSectionOffsetDirective()) {
181 // FIXME: MCize.
182 OutStreamer.EmitRawText(SecOffDir + Twine(Label->getName()));
183 return;
184 }
185
186 // Get the section that we're referring to, based on SectionLabel.
187 const MCSection &Section = SectionLabel->getSection();
188
189 // If Label has already been emitted, verify that it is in the same section as
190 // section label for sanity.
191 assert((!Label->isInSection() || &Label->getSection() == &Section) &&
192 "Section offset using wrong section base for label");
193
194 // If the section in question will end up with an address of 0 anyway, we can
195 // just emit an absolute reference to save a relocation.
196 if (Section.isBaseAddressKnownZero()) {
197 OutStreamer.EmitSymbolValue(Label, 4, 0/*AddrSpace*/);
198 return;
199 }
200
201 // Otherwise, emit it as a label difference from the start of the section.
202 EmitLabelDifference(Label, SectionLabel, 4);
203 }
204
205 //===----------------------------------------------------------------------===//
206 // Dwarf Lowering Routines
207 //===----------------------------------------------------------------------===//
208
209 /// EmitCFIFrameMove - Emit a frame instruction.
EmitCFIFrameMove(const MachineMove & Move) const210 void AsmPrinter::EmitCFIFrameMove(const MachineMove &Move) const {
211 const TargetRegisterInfo *RI = TM.getRegisterInfo();
212
213 const MachineLocation &Dst = Move.getDestination();
214 const MachineLocation &Src = Move.getSource();
215
216 // If advancing cfa.
217 if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
218 if (Src.getReg() == MachineLocation::VirtualFP) {
219 OutStreamer.EmitCFIDefCfaOffset(-Src.getOffset());
220 } else {
221 // Reg + Offset
222 OutStreamer.EmitCFIDefCfa(RI->getDwarfRegNum(Src.getReg(), true),
223 Src.getOffset());
224 }
225 } else if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
226 assert(Dst.isReg() && "Machine move not supported yet.");
227 OutStreamer.EmitCFIDefCfaRegister(RI->getDwarfRegNum(Dst.getReg(), true));
228 } else {
229 assert(!Dst.isReg() && "Machine move not supported yet.");
230 OutStreamer.EmitCFIOffset(RI->getDwarfRegNum(Src.getReg(), true),
231 Dst.getOffset());
232 }
233 }
234