AsmPrinterInlineAsm.cpp revision ce027318293ddd2a0ea0cab4e9fa6af059d3bed2 
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/Constants.h"
17#include "llvm/InlineAsm.h"
18#include "llvm/LLVMContext.h"
19#include "llvm/Module.h"
20#include "llvm/CodeGen/MachineBasicBlock.h"
21#include "llvm/CodeGen/MachineModuleInfo.h"
22#include "llvm/MC/MCAsmInfo.h"
23#include "llvm/MC/MCStreamer.h"
24#include "llvm/MC/MCSymbol.h"
25#include "llvm/Target/TargetAsmParser.h"
26#include "llvm/Target/TargetMachine.h"
27#include "llvm/Target/TargetRegistry.h"
28#include "llvm/ADT/OwningPtr.h"
29#include "llvm/ADT/SmallString.h"
30#include "llvm/ADT/Twine.h"
31#include "llvm/Support/ErrorHandling.h"
32#include "llvm/Support/MemoryBuffer.h"
33#include "llvm/Support/SourceMgr.h"
34#include "llvm/Support/raw_ostream.h"
35using namespace llvm;
36
37/// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
38void AsmPrinter::EmitInlineAsm(StringRef Str, unsigned LocCookie) const {
39  assert(!Str.empty() && "Can't emit empty inline asm block");
40
41  // Remember if the buffer is nul terminated or not so we can avoid a copy.
42  bool isNullTerminated = Str.back() == 0;
43  if (isNullTerminated)
44    Str = Str.substr(0, Str.size()-1);
45
46  // If the output streamer is actually a .s file, just emit the blob textually.
47  // This is useful in case the asm parser doesn't handle something but the
48  // system assembler does.
49  if (OutStreamer.hasRawTextSupport()) {
50    OutStreamer.EmitRawText(Str);
51    return;
52  }
53
54  SourceMgr SrcMgr;
55
56  // If the current LLVMContext has an inline asm handler, set it in SourceMgr.
57  LLVMContext &LLVMCtx = MMI->getModule()->getContext();
58  bool HasDiagHandler = false;
59  if (void *DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler()) {
60    SrcMgr.setDiagHandler((SourceMgr::DiagHandlerTy)(intptr_t)DiagHandler,
61                          LLVMCtx.getInlineAsmDiagnosticContext(), LocCookie);
62    HasDiagHandler = true;
63  }
64
65  MemoryBuffer *Buffer;
66  if (isNullTerminated)
67    Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
68  else
69    Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
70
71  // Tell SrcMgr about this buffer, it takes ownership of the buffer.
72  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
73
74  OwningPtr<MCAsmParser> Parser(createMCAsmParser(TM.getTarget(), SrcMgr,
75                                                  OutContext, OutStreamer,
76                                                  *MAI));
77  OwningPtr<TargetAsmParser> TAP(TM.getTarget().createAsmParser(*Parser, TM));
78  if (!TAP)
79    report_fatal_error("Inline asm not supported by this streamer because"
80                       " we don't have an asm parser for this target\n");
81  Parser->setTargetParser(*TAP.get());
82
83  // Don't implicitly switch to the text section before the asm.
84  int Res = Parser->Run(/*NoInitialTextSection*/ true,
85                        /*NoFinalize*/ true);
86  if (Res && !HasDiagHandler)
87    report_fatal_error("Error parsing inline asm\n");
88}
89
90
91/// EmitInlineAsm - This method formats and emits the specified machine
92/// instruction that is an inline asm.
93void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
94  assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
95
96  unsigned NumOperands = MI->getNumOperands();
97
98  // Count the number of register definitions to find the asm string.
99  unsigned NumDefs = 0;
100  for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
101       ++NumDefs)
102    assert(NumDefs != NumOperands-2 && "No asm string?");
103
104  assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
105
106  // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
107  const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
108
109  // If this asmstr is empty, just print the #APP/#NOAPP markers.
110  // These are useful to see where empty asm's wound up.
111  if (AsmStr[0] == 0) {
112    // Don't emit the comments if writing to a .o file.
113    if (!OutStreamer.hasRawTextSupport()) return;
114
115    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
116                            MAI->getInlineAsmStart());
117    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
118                            MAI->getInlineAsmEnd());
119    return;
120  }
121
122  // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
123  // enabled, so we use EmitRawText.
124  if (OutStreamer.hasRawTextSupport())
125    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
126                            MAI->getInlineAsmStart());
127
128  // Get the !srcloc metadata node if we have it, and decode the loc cookie from
129  // it.
130  unsigned LocCookie = 0;
131  for (unsigned i = MI->getNumOperands(); i != 0; --i) {
132    if (MI->getOperand(i-1).isMetadata())
133      if (const MDNode *SrcLoc = MI->getOperand(i-1).getMetadata())
134        if (SrcLoc->getNumOperands() != 0)
135          if (const ConstantInt *CI =
136              dyn_cast<ConstantInt>(SrcLoc->getOperand(0))) {
137            LocCookie = CI->getZExtValue();
138            break;
139          }
140  }
141
142  // Emit the inline asm to a temporary string so we can emit it through
143  // EmitInlineAsm.
144  SmallString<256> StringData;
145  raw_svector_ostream OS(StringData);
146
147  OS << '\t';
148
149  // The variant of the current asmprinter.
150  int AsmPrinterVariant = MAI->getAssemblerDialect();
151
152  int CurVariant = -1;            // The number of the {.|.|.} region we are in.
153  const char *LastEmitted = AsmStr; // One past the last character emitted.
154
155  while (*LastEmitted) {
156    switch (*LastEmitted) {
157    default: {
158      // Not a special case, emit the string section literally.
159      const char *LiteralEnd = LastEmitted+1;
160      while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
161             *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
162        ++LiteralEnd;
163      if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
164        OS.write(LastEmitted, LiteralEnd-LastEmitted);
165      LastEmitted = LiteralEnd;
166      break;
167    }
168    case '\n':
169      ++LastEmitted;   // Consume newline character.
170      OS << '\n';      // Indent code with newline.
171      break;
172    case '$': {
173      ++LastEmitted;   // Consume '$' character.
174      bool Done = true;
175
176      // Handle escapes.
177      switch (*LastEmitted) {
178      default: Done = false; break;
179      case '$':     // $$ -> $
180        if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
181          OS << '$';
182        ++LastEmitted;  // Consume second '$' character.
183        break;
184      case '(':             // $( -> same as GCC's { character.
185        ++LastEmitted;      // Consume '(' character.
186        if (CurVariant != -1)
187          report_fatal_error("Nested variants found in inline asm string: '" +
188                             Twine(AsmStr) + "'");
189        CurVariant = 0;     // We're in the first variant now.
190        break;
191      case '|':
192        ++LastEmitted;  // consume '|' character.
193        if (CurVariant == -1)
194          OS << '|';       // this is gcc's behavior for | outside a variant
195        else
196          ++CurVariant;   // We're in the next variant.
197        break;
198      case ')':         // $) -> same as GCC's } char.
199        ++LastEmitted;  // consume ')' character.
200        if (CurVariant == -1)
201          OS << '}';     // this is gcc's behavior for } outside a variant
202        else
203          CurVariant = -1;
204        break;
205      }
206      if (Done) break;
207
208      bool HasCurlyBraces = false;
209      if (*LastEmitted == '{') {     // ${variable}
210        ++LastEmitted;               // Consume '{' character.
211        HasCurlyBraces = true;
212      }
213
214      // If we have ${:foo}, then this is not a real operand reference, it is a
215      // "magic" string reference, just like in .td files.  Arrange to call
216      // PrintSpecial.
217      if (HasCurlyBraces && *LastEmitted == ':') {
218        ++LastEmitted;
219        const char *StrStart = LastEmitted;
220        const char *StrEnd = strchr(StrStart, '}');
221        if (StrEnd == 0)
222          report_fatal_error("Unterminated ${:foo} operand in inline asm"
223                             " string: '" + Twine(AsmStr) + "'");
224
225        std::string Val(StrStart, StrEnd);
226        PrintSpecial(MI, OS, Val.c_str());
227        LastEmitted = StrEnd+1;
228        break;
229      }
230
231      const char *IDStart = LastEmitted;
232      const char *IDEnd = IDStart;
233      while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
234
235      unsigned Val;
236      if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
237        report_fatal_error("Bad $ operand number in inline asm string: '" +
238                           Twine(AsmStr) + "'");
239      LastEmitted = IDEnd;
240
241      char Modifier[2] = { 0, 0 };
242
243      if (HasCurlyBraces) {
244        // If we have curly braces, check for a modifier character.  This
245        // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
246        if (*LastEmitted == ':') {
247          ++LastEmitted;    // Consume ':' character.
248          if (*LastEmitted == 0)
249            report_fatal_error("Bad ${:} expression in inline asm string: '" +
250                               Twine(AsmStr) + "'");
251
252          Modifier[0] = *LastEmitted;
253          ++LastEmitted;    // Consume modifier character.
254        }
255
256        if (*LastEmitted != '}')
257          report_fatal_error("Bad ${} expression in inline asm string: '" +
258                             Twine(AsmStr) + "'");
259        ++LastEmitted;    // Consume '}' character.
260      }
261
262      if (Val >= NumOperands-1)
263        report_fatal_error("Invalid $ operand number in inline asm string: '" +
264                           Twine(AsmStr) + "'");
265
266      // Okay, we finally have a value number.  Ask the target to print this
267      // operand!
268      if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
269        unsigned OpNo = 2;
270
271        bool Error = false;
272
273        // Scan to find the machine operand number for the operand.
274        for (; Val; --Val) {
275          if (OpNo >= MI->getNumOperands()) break;
276          unsigned OpFlags = MI->getOperand(OpNo).getImm();
277          OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
278        }
279
280        if (OpNo >= MI->getNumOperands()) {
281          Error = true;
282        } else {
283          unsigned OpFlags = MI->getOperand(OpNo).getImm();
284          ++OpNo;  // Skip over the ID number.
285
286          if (Modifier[0] == 'l')  // labels are target independent
287            // FIXME: What if the operand isn't an MBB, report error?
288            OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
289          else {
290            AsmPrinter *AP = const_cast<AsmPrinter*>(this);
291            if (InlineAsm::isMemKind(OpFlags)) {
292              Error = AP->PrintAsmMemoryOperand(MI, OpNo, AsmPrinterVariant,
293                                                Modifier[0] ? Modifier : 0,
294                                                OS);
295            } else {
296              Error = AP->PrintAsmOperand(MI, OpNo, AsmPrinterVariant,
297                                          Modifier[0] ? Modifier : 0, OS);
298            }
299          }
300        }
301        if (Error) {
302          std::string msg;
303          raw_string_ostream Msg(msg);
304          Msg << "invalid operand in inline asm: '" << AsmStr << "'";
305          MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
306        }
307      }
308      break;
309    }
310    }
311  }
312  OS << '\n' << (char)0;  // null terminate string.
313  EmitInlineAsm(OS.str(), LocCookie);
314
315  // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
316  // enabled, so we use EmitRawText.
317  if (OutStreamer.hasRawTextSupport())
318    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
319                            MAI->getInlineAsmEnd());
320}
321
322
323/// PrintSpecial - Print information related to the specified machine instr
324/// that is independent of the operand, and may be independent of the instr
325/// itself.  This can be useful for portably encoding the comment character
326/// or other bits of target-specific knowledge into the asmstrings.  The
327/// syntax used is ${:comment}.  Targets can override this to add support
328/// for their own strange codes.
329void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
330                              const char *Code) const {
331  if (!strcmp(Code, "private")) {
332    OS << MAI->getPrivateGlobalPrefix();
333  } else if (!strcmp(Code, "comment")) {
334    OS << MAI->getCommentString();
335  } else if (!strcmp(Code, "uid")) {
336    // Comparing the address of MI isn't sufficient, because machineinstrs may
337    // be allocated to the same address across functions.
338
339    // If this is a new LastFn instruction, bump the counter.
340    if (LastMI != MI || LastFn != getFunctionNumber()) {
341      ++Counter;
342      LastMI = MI;
343      LastFn = getFunctionNumber();
344    }
345    OS << Counter;
346  } else {
347    std::string msg;
348    raw_string_ostream Msg(msg);
349    Msg << "Unknown special formatter '" << Code
350         << "' for machine instr: " << *MI;
351    report_fatal_error(Msg.str());
352  }
353}
354
355/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
356/// instruction, using the specified assembler variant.  Targets should
357/// override this to format as appropriate.
358bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
359                                 unsigned AsmVariant, const char *ExtraCode,
360                                 raw_ostream &O) {
361  // Target doesn't support this yet!
362  return true;
363}
364
365bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
366                                       unsigned AsmVariant,
367                                       const char *ExtraCode, raw_ostream &O) {
368  // Target doesn't support this yet!
369  return true;
370}
371
372