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/ADT/Twine.h"
17 #include "llvm/IR/DataLayout.h"
18 #include "llvm/MC/MCAsmInfo.h"
19 #include "llvm/MC/MCSection.h"
20 #include "llvm/MC/MCStreamer.h"
21 #include "llvm/MC/MCSymbol.h"
22 #include "llvm/MC/MachineLocation.h"
23 #include "llvm/Support/Dwarf.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Target/TargetFrameLowering.h"
26 #include "llvm/Target/TargetLoweringObjectFile.h"
27 #include "llvm/Target/TargetMachine.h"
28 #include "llvm/Target/TargetRegisterInfo.h"
29 using namespace llvm;
30
31 //===----------------------------------------------------------------------===//
32 // Dwarf Emission Helper Routines
33 //===----------------------------------------------------------------------===//
34
35 /// EmitSLEB128 - emit the specified signed leb128 value.
EmitSLEB128(int Value,const char * Desc) const36 void AsmPrinter::EmitSLEB128(int Value, const char *Desc) const {
37 if (isVerbose() && Desc)
38 OutStreamer.AddComment(Desc);
39
40 OutStreamer.EmitSLEB128IntValue(Value);
41 }
42
43 /// EmitULEB128 - emit the specified signed leb128 value.
EmitULEB128(unsigned Value,const char * Desc,unsigned PadTo) const44 void AsmPrinter::EmitULEB128(unsigned Value, const char *Desc,
45 unsigned PadTo) const {
46 if (isVerbose() && Desc)
47 OutStreamer.AddComment(Desc);
48
49 OutStreamer.EmitULEB128IntValue(Value, PadTo);
50 }
51
52 /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
EmitCFAByte(unsigned Val) const53 void AsmPrinter::EmitCFAByte(unsigned Val) const {
54 if (isVerbose()) {
55 if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset+64)
56 OutStreamer.AddComment("DW_CFA_offset + Reg (" +
57 Twine(Val-dwarf::DW_CFA_offset) + ")");
58 else
59 OutStreamer.AddComment(dwarf::CallFrameString(Val));
60 }
61 OutStreamer.EmitIntValue(Val, 1);
62 }
63
DecodeDWARFEncoding(unsigned Encoding)64 static const char *DecodeDWARFEncoding(unsigned Encoding) {
65 switch (Encoding) {
66 case dwarf::DW_EH_PE_absptr: return "absptr";
67 case dwarf::DW_EH_PE_omit: return "omit";
68 case dwarf::DW_EH_PE_pcrel: return "pcrel";
69 case dwarf::DW_EH_PE_udata4: return "udata4";
70 case dwarf::DW_EH_PE_udata8: return "udata8";
71 case dwarf::DW_EH_PE_sdata4: return "sdata4";
72 case dwarf::DW_EH_PE_sdata8: return "sdata8";
73 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: return "pcrel udata4";
74 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: return "pcrel sdata4";
75 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: return "pcrel udata8";
76 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: return "pcrel sdata8";
77 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata4:
78 return "indirect pcrel udata4";
79 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata4:
80 return "indirect pcrel sdata4";
81 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata8:
82 return "indirect pcrel udata8";
83 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata8:
84 return "indirect pcrel sdata8";
85 }
86
87 return "<unknown encoding>";
88 }
89
90
91 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
92 /// encoding. If verbose assembly output is enabled, we output comments
93 /// describing the encoding. Desc is an optional string saying what the
94 /// encoding is specifying (e.g. "LSDA").
EmitEncodingByte(unsigned Val,const char * Desc) const95 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
96 if (isVerbose()) {
97 if (Desc != 0)
98 OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
99 Twine(DecodeDWARFEncoding(Val)));
100 else
101 OutStreamer.AddComment(Twine("Encoding = ") +
102 DecodeDWARFEncoding(Val));
103 }
104
105 OutStreamer.EmitIntValue(Val, 1);
106 }
107
108 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
GetSizeOfEncodedValue(unsigned Encoding) const109 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
110 if (Encoding == dwarf::DW_EH_PE_omit)
111 return 0;
112
113 switch (Encoding & 0x07) {
114 default: llvm_unreachable("Invalid encoded value.");
115 case dwarf::DW_EH_PE_absptr: return TM.getDataLayout()->getPointerSize();
116 case dwarf::DW_EH_PE_udata2: return 2;
117 case dwarf::DW_EH_PE_udata4: return 4;
118 case dwarf::DW_EH_PE_udata8: return 8;
119 }
120 }
121
EmitTTypeReference(const GlobalValue * GV,unsigned Encoding) const122 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
123 unsigned Encoding) const {
124 if (GV) {
125 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
126
127 const MCExpr *Exp =
128 TLOF.getTTypeGlobalReference(GV, Mang, MMI, Encoding, OutStreamer);
129 OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
130 } else
131 OutStreamer.EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
132 }
133
134 /// EmitSectionOffset - Emit the 4-byte offset of Label from the start of its
135 /// section. This can be done with a special directive if the target supports
136 /// it (e.g. cygwin) or by emitting it as an offset from a label at the start
137 /// of the section.
138 ///
139 /// SectionLabel is a temporary label emitted at the start of the section that
140 /// Label lives in.
EmitSectionOffset(const MCSymbol * Label,const MCSymbol * SectionLabel) const141 void AsmPrinter::EmitSectionOffset(const MCSymbol *Label,
142 const MCSymbol *SectionLabel) const {
143 // On COFF targets, we have to emit the special .secrel32 directive.
144 if (MAI->getDwarfSectionOffsetDirective()) {
145 OutStreamer.EmitCOFFSecRel32(Label);
146 return;
147 }
148
149 // Get the section that we're referring to, based on SectionLabel.
150 const MCSection &Section = SectionLabel->getSection();
151
152 // If Label has already been emitted, verify that it is in the same section as
153 // section label for sanity.
154 assert((!Label->isInSection() || &Label->getSection() == &Section) &&
155 "Section offset using wrong section base for label");
156
157 // If the section in question will end up with an address of 0 anyway, we can
158 // just emit an absolute reference to save a relocation.
159 if (Section.isBaseAddressKnownZero()) {
160 OutStreamer.EmitSymbolValue(Label, 4);
161 return;
162 }
163
164 // Otherwise, emit it as a label difference from the start of the section.
165 EmitLabelDifference(Label, SectionLabel, 4);
166 }
167
168 //===----------------------------------------------------------------------===//
169 // Dwarf Lowering Routines
170 //===----------------------------------------------------------------------===//
171
172 /// EmitCFIFrameMove - Emit a frame instruction.
EmitCFIFrameMove(const MachineMove & Move) const173 void AsmPrinter::EmitCFIFrameMove(const MachineMove &Move) const {
174 const TargetRegisterInfo *RI = TM.getRegisterInfo();
175
176 const MachineLocation &Dst = Move.getDestination();
177 const MachineLocation &Src = Move.getSource();
178
179 // If advancing cfa.
180 if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
181 if (Src.getReg() == MachineLocation::VirtualFP) {
182 OutStreamer.EmitCFIDefCfaOffset(-Src.getOffset());
183 } else {
184 // Reg + Offset
185 OutStreamer.EmitCFIDefCfa(RI->getDwarfRegNum(Src.getReg(), true),
186 Src.getOffset());
187 }
188 } else if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
189 assert(Dst.isReg() && "Machine move not supported yet.");
190 OutStreamer.EmitCFIDefCfaRegister(RI->getDwarfRegNum(Dst.getReg(), true));
191 } else {
192 assert(!Dst.isReg() && "Machine move not supported yet.");
193 OutStreamer.EmitCFIOffset(RI->getDwarfRegNum(Src.getReg(), true),
194 Dst.getOffset());
195 }
196 }
197