AsmPrinterInlineAsm.cpp revision 76a8ffffa1f89e17ce3f5c207d7231a354b161e6 
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/MC/MCParser/AsmParser.h"
22#include "llvm/Target/TargetAsmParser.h"
23#include "llvm/Target/TargetMachine.h"
24#include "llvm/Target/TargetRegistry.h"
25#include "llvm/ADT/OwningPtr.h"
26#include "llvm/ADT/SmallString.h"
27#include "llvm/ADT/Twine.h"
28#include "llvm/Support/ErrorHandling.h"
29#include "llvm/Support/MemoryBuffer.h"
30#include "llvm/Support/SourceMgr.h"
31#include "llvm/Support/raw_ostream.h"
32using namespace llvm;
33
34/// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
35void AsmPrinter::EmitInlineAsm(StringRef Str) const {
36  assert(!Str.empty() && "Can't emit empty inline asm block");
37
38  // Remember if the buffer is nul terminated or not so we can avoid a copy.
39  bool isNullTerminated = Str.back() == 0;
40  if (isNullTerminated)
41    Str = Str.substr(0, Str.size()-1);
42
43  // If the output streamer is actually a .s file, just emit the blob textually.
44  // This is useful in case the asm parser doesn't handle something but the
45  // system assembler does.
46  if (OutStreamer.hasRawTextSupport()) {
47    OutStreamer.EmitRawText(Str);
48    return;
49  }
50
51  SourceMgr SrcMgr;
52  MemoryBuffer *Buffer;
53  if (isNullTerminated)
54    Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
55  else
56    Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
57
58  // Tell SrcMgr about this buffer, it takes ownership of the buffer.
59  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
60
61  AsmParser Parser(SrcMgr, OutContext, OutStreamer, *MAI);
62  OwningPtr<TargetAsmParser> TAP(TM.getTarget().createAsmParser(Parser));
63  if (!TAP)
64    llvm_report_error("Inline asm not supported by this streamer because"
65                      " we don't have an asm parser for this target\n");
66  Parser.setTargetParser(*TAP.get());
67
68  // Don't implicitly switch to the text section before the asm.
69  int Res = Parser.Run(/*NoInitialTextSection*/ true,
70                       /*NoFinalize*/ true);
71  if (Res)
72    llvm_report_error("Error parsing inline asm\n");
73}
74
75
76/// EmitInlineAsm - This method formats and emits the specified machine
77/// instruction that is an inline asm.
78void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
79  assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
80
81  unsigned NumOperands = MI->getNumOperands();
82
83  // Count the number of register definitions to find the asm string.
84  unsigned NumDefs = 0;
85  for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
86       ++NumDefs)
87    assert(NumDefs != NumOperands-1 && "No asm string?");
88
89  assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
90
91  // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
92  const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
93
94  // If this asmstr is empty, just print the #APP/#NOAPP markers.
95  // These are useful to see where empty asm's wound up.
96  if (AsmStr[0] == 0) {
97    // Don't emit the comments if writing to a .o file.
98    if (!OutStreamer.hasRawTextSupport()) return;
99
100    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
101                            MAI->getInlineAsmStart());
102    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
103                            MAI->getInlineAsmEnd());
104    return;
105  }
106
107  // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
108  // enabled, so we use EmitRawText.
109  if (OutStreamer.hasRawTextSupport())
110    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
111                            MAI->getInlineAsmStart());
112
113  // Emit the inline asm to a temporary string so we can emit it through
114  // EmitInlineAsm.
115  SmallString<256> StringData;
116  raw_svector_ostream OS(StringData);
117
118  OS << '\t';
119
120  // The variant of the current asmprinter.
121  int AsmPrinterVariant = MAI->getAssemblerDialect();
122
123  int CurVariant = -1;            // The number of the {.|.|.} region we are in.
124  const char *LastEmitted = AsmStr; // One past the last character emitted.
125
126  while (*LastEmitted) {
127    switch (*LastEmitted) {
128    default: {
129      // Not a special case, emit the string section literally.
130      const char *LiteralEnd = LastEmitted+1;
131      while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
132             *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
133        ++LiteralEnd;
134      if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
135        OS.write(LastEmitted, LiteralEnd-LastEmitted);
136      LastEmitted = LiteralEnd;
137      break;
138    }
139    case '\n':
140      ++LastEmitted;   // Consume newline character.
141      OS << '\n';      // Indent code with newline.
142      break;
143    case '$': {
144      ++LastEmitted;   // Consume '$' character.
145      bool Done = true;
146
147      // Handle escapes.
148      switch (*LastEmitted) {
149      default: Done = false; break;
150      case '$':     // $$ -> $
151        if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
152          OS << '$';
153        ++LastEmitted;  // Consume second '$' character.
154        break;
155      case '(':             // $( -> same as GCC's { character.
156        ++LastEmitted;      // Consume '(' character.
157        if (CurVariant != -1) {
158          llvm_report_error("Nested variants found in inline asm string: '"
159                            + std::string(AsmStr) + "'");
160        }
161        CurVariant = 0;     // We're in the first variant now.
162        break;
163      case '|':
164        ++LastEmitted;  // consume '|' character.
165        if (CurVariant == -1)
166          OS << '|';       // this is gcc's behavior for | outside a variant
167        else
168          ++CurVariant;   // We're in the next variant.
169        break;
170      case ')':         // $) -> same as GCC's } char.
171        ++LastEmitted;  // consume ')' character.
172        if (CurVariant == -1)
173          OS << '}';     // this is gcc's behavior for } outside a variant
174        else
175          CurVariant = -1;
176        break;
177      }
178      if (Done) break;
179
180      bool HasCurlyBraces = false;
181      if (*LastEmitted == '{') {     // ${variable}
182        ++LastEmitted;               // Consume '{' character.
183        HasCurlyBraces = true;
184      }
185
186      // If we have ${:foo}, then this is not a real operand reference, it is a
187      // "magic" string reference, just like in .td files.  Arrange to call
188      // PrintSpecial.
189      if (HasCurlyBraces && *LastEmitted == ':') {
190        ++LastEmitted;
191        const char *StrStart = LastEmitted;
192        const char *StrEnd = strchr(StrStart, '}');
193        if (StrEnd == 0)
194          llvm_report_error(Twine("Unterminated ${:foo} operand in inline asm"
195                                  " string: '") + Twine(AsmStr) + "'");
196
197        std::string Val(StrStart, StrEnd);
198        PrintSpecial(MI, OS, Val.c_str());
199        LastEmitted = StrEnd+1;
200        break;
201      }
202
203      const char *IDStart = LastEmitted;
204      const char *IDEnd = IDStart;
205      while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
206
207      unsigned Val;
208      if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
209        llvm_report_error("Bad $ operand number in inline asm string: '"
210                          + std::string(AsmStr) + "'");
211      LastEmitted = IDEnd;
212
213      char Modifier[2] = { 0, 0 };
214
215      if (HasCurlyBraces) {
216        // If we have curly braces, check for a modifier character.  This
217        // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
218        if (*LastEmitted == ':') {
219          ++LastEmitted;    // Consume ':' character.
220          if (*LastEmitted == 0)
221            llvm_report_error("Bad ${:} expression in inline asm string: '" +
222                              std::string(AsmStr) + "'");
223
224          Modifier[0] = *LastEmitted;
225          ++LastEmitted;    // Consume modifier character.
226        }
227
228        if (*LastEmitted != '}')
229          llvm_report_error("Bad ${} expression in inline asm string: '"
230                            + std::string(AsmStr) + "'");
231        ++LastEmitted;    // Consume '}' character.
232      }
233
234      if (Val >= NumOperands-1)
235        llvm_report_error("Invalid $ operand number in inline asm string: '"
236                          + std::string(AsmStr) + "'");
237
238      // Okay, we finally have a value number.  Ask the target to print this
239      // operand!
240      if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
241        unsigned OpNo = 1;
242
243        bool Error = false;
244
245        // Scan to find the machine operand number for the operand.
246        for (; Val; --Val) {
247          if (OpNo >= MI->getNumOperands()) break;
248          unsigned OpFlags = MI->getOperand(OpNo).getImm();
249          OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
250        }
251
252        if (OpNo >= MI->getNumOperands()) {
253          Error = true;
254        } else {
255          unsigned OpFlags = MI->getOperand(OpNo).getImm();
256          ++OpNo;  // Skip over the ID number.
257
258          if (Modifier[0] == 'l')  // labels are target independent
259            // FIXME: What if the operand isn't an MBB, report error?
260            OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
261          else {
262            AsmPrinter *AP = const_cast<AsmPrinter*>(this);
263            if ((OpFlags & 7) == 4) {
264              Error = AP->PrintAsmMemoryOperand(MI, OpNo, AsmPrinterVariant,
265                                                Modifier[0] ? Modifier : 0,
266                                                OS);
267            } else {
268              Error = AP->PrintAsmOperand(MI, OpNo, AsmPrinterVariant,
269                                          Modifier[0] ? Modifier : 0, OS);
270            }
271          }
272        }
273        if (Error) {
274          std::string msg;
275          raw_string_ostream Msg(msg);
276          Msg << "Invalid operand found in inline asm: '" << AsmStr << "'\n";
277          MI->print(Msg);
278          llvm_report_error(Msg.str());
279        }
280      }
281      break;
282    }
283    }
284  }
285  OS << '\n' << (char)0;  // null terminate string.
286  EmitInlineAsm(OS.str());
287
288  // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
289  // enabled, so we use EmitRawText.
290  if (OutStreamer.hasRawTextSupport())
291    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
292                            MAI->getInlineAsmEnd());
293}
294
295
296/// PrintSpecial - Print information related to the specified machine instr
297/// that is independent of the operand, and may be independent of the instr
298/// itself.  This can be useful for portably encoding the comment character
299/// or other bits of target-specific knowledge into the asmstrings.  The
300/// syntax used is ${:comment}.  Targets can override this to add support
301/// for their own strange codes.
302void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
303                              const char *Code) const {
304  if (!strcmp(Code, "private")) {
305    OS << MAI->getPrivateGlobalPrefix();
306  } else if (!strcmp(Code, "comment")) {
307    OS << MAI->getCommentString();
308  } else if (!strcmp(Code, "uid")) {
309    // Comparing the address of MI isn't sufficient, because machineinstrs may
310    // be allocated to the same address across functions.
311
312    // If this is a new LastFn instruction, bump the counter.
313    if (LastMI != MI || LastFn != getFunctionNumber()) {
314      ++Counter;
315      LastMI = MI;
316      LastFn = getFunctionNumber();
317    }
318    OS << Counter;
319  } else {
320    std::string msg;
321    raw_string_ostream Msg(msg);
322    Msg << "Unknown special formatter '" << Code
323         << "' for machine instr: " << *MI;
324    llvm_report_error(Msg.str());
325  }
326}
327
328/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
329/// instruction, using the specified assembler variant.  Targets should
330/// override this to format as appropriate.
331bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
332                                 unsigned AsmVariant, const char *ExtraCode,
333                                 raw_ostream &O) {
334  // Target doesn't support this yet!
335  return true;
336}
337
338bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
339                                       unsigned AsmVariant,
340                                       const char *ExtraCode, raw_ostream &O) {
341  // Target doesn't support this yet!
342  return true;
343}
344
345