AsmPrinterDwarf.cpp revision 28e23aa64c3c2c93dfa10856ea413b2086251fdf 
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/MCAsmInfo.h"
17#include "llvm/MC/MCStreamer.h"
18#include "llvm/ADT/Twine.h"
19#include "llvm/Support/Dwarf.h"
20using namespace llvm;
21
22/// EmitSLEB128 - emit the specified signed leb128 value.
23void AsmPrinter::EmitSLEB128(int Value, const char *Desc) const {
24  if (isVerbose() && Desc)
25    OutStreamer.AddComment(Desc);
26
27  if (MAI->hasLEB128()) {
28    // FIXME: MCize.
29    OutStreamer.EmitRawText("\t.sleb128\t" + Twine(Value));
30    return;
31  }
32
33  // If we don't have .sleb128, emit as .bytes.
34  int Sign = Value >> (8 * sizeof(Value) - 1);
35  bool IsMore;
36
37  do {
38    unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
39    Value >>= 7;
40    IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
41    if (IsMore) Byte |= 0x80;
42    OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
43  } while (IsMore);
44}
45
46/// EmitULEB128 - emit the specified signed leb128 value.
47void AsmPrinter::EmitULEB128(unsigned Value, const char *Desc,
48                             unsigned PadTo) const {
49  if (isVerbose() && Desc)
50    OutStreamer.AddComment(Desc);
51
52  if (MAI->hasLEB128() && PadTo == 0) {
53    // FIXME: MCize.
54    OutStreamer.EmitRawText("\t.uleb128\t" + Twine(Value));
55    return;
56  }
57
58  // If we don't have .uleb128 or we want to emit padding, emit as .bytes.
59  do {
60    unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
61    Value >>= 7;
62    if (Value || PadTo != 0) Byte |= 0x80;
63    OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
64  } while (Value);
65
66  if (PadTo) {
67    if (PadTo > 1)
68      OutStreamer.EmitFill(PadTo - 1, 0x80/*fillval*/, 0/*addrspace*/);
69    OutStreamer.EmitFill(1, 0/*fillval*/, 0/*addrspace*/);
70  }
71}
72
73/// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
74void AsmPrinter::EmitCFAByte(unsigned Val) const {
75  if (isVerbose()) {
76    if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset+64)
77      OutStreamer.AddComment("DW_CFA_offset + Reg (" +
78                             Twine(Val-dwarf::DW_CFA_offset) + ")");
79    else
80      OutStreamer.AddComment(dwarf::CallFrameString(Val));
81  }
82  OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
83}
84
85static const char *DecodeDWARFEncoding(unsigned Encoding) {
86  switch (Encoding) {
87  case dwarf::DW_EH_PE_absptr: return "absptr";
88  case dwarf::DW_EH_PE_omit:   return "omit";
89  case dwarf::DW_EH_PE_pcrel:  return "pcrel";
90  case dwarf::DW_EH_PE_udata4: return "udata4";
91  case dwarf::DW_EH_PE_udata8: return "udata8";
92  case dwarf::DW_EH_PE_sdata4: return "sdata4";
93  case dwarf::DW_EH_PE_sdata8: return "sdata8";
94  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: return "pcrel udata4";
95  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: return "pcrel sdata4";
96  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: return "pcrel udata8";
97  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: return "pcrel sdata8";
98  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata4:
99    return "indirect pcrel udata4";
100  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata4:
101    return "indirect pcrel sdata4";
102  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata8:
103    return "indirect pcrel udata8";
104  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata8:
105    return "indirect pcrel sdata8";
106  }
107
108  return "<unknown encoding>";
109}
110
111
112/// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
113/// encoding.  If verbose assembly output is enabled, we output comments
114/// describing the encoding.  Desc is an optional string saying what the
115/// encoding is specifying (e.g. "LSDA").
116void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) {
117  if (isVerbose()) {
118    if (Desc != 0)
119      OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
120                             Twine(DecodeDWARFEncoding(Val)));
121    else
122      OutStreamer.AddComment(Twine("Encoding = ") +
123                             DecodeDWARFEncoding(Val));
124  }
125
126  OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
127}
128
129