AsmPrinterInlineAsm.cpp revision 7fb59c6cad5a7e3ae621e0fedcbc67fea3ea13fe 
1//===-- AsmPrinterInlineAsm.cpp - AsmPrinter Inline Asm Handling ----------===//
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 inline assembler pieces of the AsmPrinter class.
11//
12//===----------------------------------------------------------------------===//
13
14#define DEBUG_TYPE "asm-printer"
15#include "llvm/CodeGen/AsmPrinter.h"
16#include "llvm/InlineAsm.h"
17#include "llvm/CodeGen/MachineBasicBlock.h"
18#include "llvm/MC/MCAsmInfo.h"
19#include "llvm/MC/MCStreamer.h"
20#include "llvm/MC/MCSymbol.h"
21#include "llvm/ADT/SmallString.h"
22#include "llvm/ADT/Twine.h"
23#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/raw_ostream.h"
25using namespace llvm;
26
27/// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
28void AsmPrinter::EmitInlineAsm(StringRef Str) const {
29  assert(!Str.empty() && "Can't emit empty inline asm block");
30
31  // If the output streamer is actually a .s file, just emit the blob textually.
32  // This is useful in case the asm parser doesn't handle something but the
33  // system assembler does.
34  if (OutStreamer.hasRawTextSupport()) {
35    OutStreamer.EmitRawText(Str);
36    return;
37  }
38
39  errs() << "Inline asm not supported by this streamer!\n";
40}
41
42
43/// EmitInlineAsm - This method formats and emits the specified machine
44/// instruction that is an inline asm.
45void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
46  assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
47
48  unsigned NumOperands = MI->getNumOperands();
49
50  // Count the number of register definitions to find the asm string.
51  unsigned NumDefs = 0;
52  for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
53       ++NumDefs)
54    assert(NumDefs != NumOperands-1 && "No asm string?");
55
56  assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
57
58  // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
59  const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
60
61  // If this asmstr is empty, just print the #APP/#NOAPP markers.
62  // These are useful to see where empty asm's wound up.
63  if (AsmStr[0] == 0) {
64    // Don't emit the comments if writing to a .o file.
65    if (!OutStreamer.hasRawTextSupport()) return;
66
67    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
68                            MAI->getInlineAsmStart());
69    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
70                            MAI->getInlineAsmEnd());
71    return;
72  }
73
74  // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
75  // enabled, so we use EmitRawText.
76  if (OutStreamer.hasRawTextSupport())
77    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
78                            MAI->getInlineAsmStart());
79
80  // Emit the inline asm to a temporary string so we can emit it through
81  // EmitInlineAsm.
82  SmallString<256> StringData;
83  raw_svector_ostream OS(StringData);
84
85  OS << '\t';
86
87  // The variant of the current asmprinter.
88  int AsmPrinterVariant = MAI->getAssemblerDialect();
89
90  int CurVariant = -1;            // The number of the {.|.|.} region we are in.
91  const char *LastEmitted = AsmStr; // One past the last character emitted.
92
93  while (*LastEmitted) {
94    switch (*LastEmitted) {
95    default: {
96      // Not a special case, emit the string section literally.
97      const char *LiteralEnd = LastEmitted+1;
98      while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
99             *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
100        ++LiteralEnd;
101      if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
102        OS.write(LastEmitted, LiteralEnd-LastEmitted);
103      LastEmitted = LiteralEnd;
104      break;
105    }
106    case '\n':
107      ++LastEmitted;   // Consume newline character.
108      OS << '\n';      // Indent code with newline.
109      break;
110    case '$': {
111      ++LastEmitted;   // Consume '$' character.
112      bool Done = true;
113
114      // Handle escapes.
115      switch (*LastEmitted) {
116      default: Done = false; break;
117      case '$':     // $$ -> $
118        if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
119          OS << '$';
120        ++LastEmitted;  // Consume second '$' character.
121        break;
122      case '(':             // $( -> same as GCC's { character.
123        ++LastEmitted;      // Consume '(' character.
124        if (CurVariant != -1) {
125          llvm_report_error("Nested variants found in inline asm string: '"
126                            + std::string(AsmStr) + "'");
127        }
128        CurVariant = 0;     // We're in the first variant now.
129        break;
130      case '|':
131        ++LastEmitted;  // consume '|' character.
132        if (CurVariant == -1)
133          OS << '|';       // this is gcc's behavior for | outside a variant
134        else
135          ++CurVariant;   // We're in the next variant.
136        break;
137      case ')':         // $) -> same as GCC's } char.
138        ++LastEmitted;  // consume ')' character.
139        if (CurVariant == -1)
140          OS << '}';     // this is gcc's behavior for } outside a variant
141        else
142          CurVariant = -1;
143        break;
144      }
145      if (Done) break;
146
147      bool HasCurlyBraces = false;
148      if (*LastEmitted == '{') {     // ${variable}
149        ++LastEmitted;               // Consume '{' character.
150        HasCurlyBraces = true;
151      }
152
153      // If we have ${:foo}, then this is not a real operand reference, it is a
154      // "magic" string reference, just like in .td files.  Arrange to call
155      // PrintSpecial.
156      if (HasCurlyBraces && *LastEmitted == ':') {
157        ++LastEmitted;
158        const char *StrStart = LastEmitted;
159        const char *StrEnd = strchr(StrStart, '}');
160        if (StrEnd == 0)
161          llvm_report_error(Twine("Unterminated ${:foo} operand in inline asm"
162                                  " string: '") + Twine(AsmStr) + "'");
163
164        std::string Val(StrStart, StrEnd);
165        PrintSpecial(MI, OS, Val.c_str());
166        LastEmitted = StrEnd+1;
167        break;
168      }
169
170      const char *IDStart = LastEmitted;
171      const char *IDEnd = IDStart;
172      while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
173
174      unsigned Val;
175      if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
176        llvm_report_error("Bad $ operand number in inline asm string: '"
177                          + std::string(AsmStr) + "'");
178      LastEmitted = IDEnd;
179
180      char Modifier[2] = { 0, 0 };
181
182      if (HasCurlyBraces) {
183        // If we have curly braces, check for a modifier character.  This
184        // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
185        if (*LastEmitted == ':') {
186          ++LastEmitted;    // Consume ':' character.
187          if (*LastEmitted == 0)
188            llvm_report_error("Bad ${:} expression in inline asm string: '" +
189                              std::string(AsmStr) + "'");
190
191          Modifier[0] = *LastEmitted;
192          ++LastEmitted;    // Consume modifier character.
193        }
194
195        if (*LastEmitted != '}')
196          llvm_report_error("Bad ${} expression in inline asm string: '"
197                            + std::string(AsmStr) + "'");
198        ++LastEmitted;    // Consume '}' character.
199      }
200
201      if (Val >= NumOperands-1)
202        llvm_report_error("Invalid $ operand number in inline asm string: '"
203                          + std::string(AsmStr) + "'");
204
205      // Okay, we finally have a value number.  Ask the target to print this
206      // operand!
207      if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
208        unsigned OpNo = 1;
209
210        bool Error = false;
211
212        // Scan to find the machine operand number for the operand.
213        for (; Val; --Val) {
214          if (OpNo >= MI->getNumOperands()) break;
215          unsigned OpFlags = MI->getOperand(OpNo).getImm();
216          OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
217        }
218
219        if (OpNo >= MI->getNumOperands()) {
220          Error = true;
221        } else {
222          unsigned OpFlags = MI->getOperand(OpNo).getImm();
223          ++OpNo;  // Skip over the ID number.
224
225          if (Modifier[0] == 'l')  // labels are target independent
226            // FIXME: What if the operand isn't an MBB, report error?
227            OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
228          else {
229            AsmPrinter *AP = const_cast<AsmPrinter*>(this);
230            if ((OpFlags & 7) == 4) {
231              Error = AP->PrintAsmMemoryOperand(MI, OpNo, AsmPrinterVariant,
232                                                Modifier[0] ? Modifier : 0,
233                                                OS);
234            } else {
235              Error = AP->PrintAsmOperand(MI, OpNo, AsmPrinterVariant,
236                                          Modifier[0] ? Modifier : 0, OS);
237            }
238          }
239        }
240        if (Error) {
241          std::string msg;
242          raw_string_ostream Msg(msg);
243          Msg << "Invalid operand found in inline asm: '" << AsmStr << "'\n";
244          MI->print(Msg);
245          llvm_report_error(Msg.str());
246        }
247      }
248      break;
249    }
250    }
251  }
252  OS << "\n";
253
254  EmitInlineAsm(OS.str());
255
256  // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
257  // enabled, so we use EmitRawText.
258  if (OutStreamer.hasRawTextSupport())
259    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
260                            MAI->getInlineAsmEnd());
261}
262
263
264/// PrintSpecial - Print information related to the specified machine instr
265/// that is independent of the operand, and may be independent of the instr
266/// itself.  This can be useful for portably encoding the comment character
267/// or other bits of target-specific knowledge into the asmstrings.  The
268/// syntax used is ${:comment}.  Targets can override this to add support
269/// for their own strange codes.
270void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
271                              const char *Code) const {
272  if (!strcmp(Code, "private")) {
273    OS << MAI->getPrivateGlobalPrefix();
274  } else if (!strcmp(Code, "comment")) {
275    OS << MAI->getCommentString();
276  } else if (!strcmp(Code, "uid")) {
277    // Comparing the address of MI isn't sufficient, because machineinstrs may
278    // be allocated to the same address across functions.
279
280    // If this is a new LastFn instruction, bump the counter.
281    if (LastMI != MI || LastFn != getFunctionNumber()) {
282      ++Counter;
283      LastMI = MI;
284      LastFn = getFunctionNumber();
285    }
286    OS << Counter;
287  } else {
288    std::string msg;
289    raw_string_ostream Msg(msg);
290    Msg << "Unknown special formatter '" << Code
291         << "' for machine instr: " << *MI;
292    llvm_report_error(Msg.str());
293  }
294}
295
296/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
297/// instruction, using the specified assembler variant.  Targets should
298/// override this to format as appropriate.
299bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
300                                 unsigned AsmVariant, const char *ExtraCode,
301                                 raw_ostream &O) {
302  // Target doesn't support this yet!
303  return true;
304}
305
306bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
307                                       unsigned AsmVariant,
308                                       const char *ExtraCode, raw_ostream &O) {
309  // Target doesn't support this yet!
310  return true;
311}
312
313