AsmPrinterInlineAsm.cpp revision a7cfc08ebe737062917b442830eb5321b0f79e89 
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/MCSubtargetInfo.h"
25#include "llvm/MC/MCSymbol.h"
26#include "llvm/MC/TargetAsmParser.h"
27#include "llvm/Target/TargetMachine.h"
28#include "llvm/Target/TargetRegistry.h"
29#include "llvm/ADT/OwningPtr.h"
30#include "llvm/ADT/SmallString.h"
31#include "llvm/ADT/Twine.h"
32#include "llvm/Support/ErrorHandling.h"
33#include "llvm/Support/MemoryBuffer.h"
34#include "llvm/Support/SourceMgr.h"
35#include "llvm/Support/raw_ostream.h"
36using namespace llvm;
37
38namespace {
39  struct SrcMgrDiagInfo {
40    const MDNode *LocInfo;
41    LLVMContext::InlineAsmDiagHandlerTy DiagHandler;
42    void *DiagContext;
43  };
44}
45
46/// SrcMgrDiagHandler - This callback is invoked when the SourceMgr for an
47/// inline asm has an error in it.  diagInfo is a pointer to the SrcMgrDiagInfo
48/// struct above.
49static void SrcMgrDiagHandler(const SMDiagnostic &Diag, void *diagInfo) {
50  SrcMgrDiagInfo *DiagInfo = static_cast<SrcMgrDiagInfo *>(diagInfo);
51  assert(DiagInfo && "Diagnostic context not passed down?");
52
53  // If the inline asm had metadata associated with it, pull out a location
54  // cookie corresponding to which line the error occurred on.
55  unsigned LocCookie = 0;
56  if (const MDNode *LocInfo = DiagInfo->LocInfo) {
57    unsigned ErrorLine = Diag.getLineNo()-1;
58    if (ErrorLine >= LocInfo->getNumOperands())
59      ErrorLine = 0;
60
61    if (LocInfo->getNumOperands() != 0)
62      if (const ConstantInt *CI =
63          dyn_cast<ConstantInt>(LocInfo->getOperand(ErrorLine)))
64        LocCookie = CI->getZExtValue();
65  }
66
67  DiagInfo->DiagHandler(Diag, DiagInfo->DiagContext, LocCookie);
68}
69
70/// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
71void AsmPrinter::EmitInlineAsm(StringRef Str, const MDNode *LocMDNode) const {
72  assert(!Str.empty() && "Can't emit empty inline asm block");
73
74  // Remember if the buffer is nul terminated or not so we can avoid a copy.
75  bool isNullTerminated = Str.back() == 0;
76  if (isNullTerminated)
77    Str = Str.substr(0, Str.size()-1);
78
79  // If the output streamer is actually a .s file, just emit the blob textually.
80  // This is useful in case the asm parser doesn't handle something but the
81  // system assembler does.
82  if (OutStreamer.hasRawTextSupport()) {
83    OutStreamer.EmitRawText(Str);
84    return;
85  }
86
87  SourceMgr SrcMgr;
88  SrcMgrDiagInfo DiagInfo;
89
90  // If the current LLVMContext has an inline asm handler, set it in SourceMgr.
91  LLVMContext &LLVMCtx = MMI->getModule()->getContext();
92  bool HasDiagHandler = false;
93  if (LLVMCtx.getInlineAsmDiagnosticHandler() != 0) {
94    // If the source manager has an issue, we arrange for SrcMgrDiagHandler
95    // to be invoked, getting DiagInfo passed into it.
96    DiagInfo.LocInfo = LocMDNode;
97    DiagInfo.DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler();
98    DiagInfo.DiagContext = LLVMCtx.getInlineAsmDiagnosticContext();
99    SrcMgr.setDiagHandler(SrcMgrDiagHandler, &DiagInfo);
100    HasDiagHandler = true;
101  }
102
103  MemoryBuffer *Buffer;
104  if (isNullTerminated)
105    Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
106  else
107    Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
108
109  // Tell SrcMgr about this buffer, it takes ownership of the buffer.
110  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
111
112  OwningPtr<MCAsmParser> Parser(createMCAsmParser(TM.getTarget(), SrcMgr,
113                                                  OutContext, OutStreamer,
114                                                  *MAI));
115
116  // FIXME: It would be nice if we can avoid createing a new instance of
117  // MCSubtargetInfo here given TargetSubtargetInfo is available. However,
118  // we have to watch out for asm directives which can change subtarget
119  // state. e.g. .code 16, .code 32.
120  OwningPtr<MCSubtargetInfo>
121    STI(TM.getTarget().createMCSubtargetInfo(TM.getTargetTriple(),
122                                             TM.getTargetCPU(),
123                                             TM.getTargetFeatureString()));
124  OwningPtr<TargetAsmParser> TAP(TM.getTarget().createAsmParser(*STI, *Parser));
125  if (!TAP)
126    report_fatal_error("Inline asm not supported by this streamer because"
127                       " we don't have an asm parser for this target\n");
128  Parser->setTargetParser(*TAP.get());
129
130  // Don't implicitly switch to the text section before the asm.
131  int Res = Parser->Run(/*NoInitialTextSection*/ true,
132                        /*NoFinalize*/ true);
133  if (Res && !HasDiagHandler)
134    report_fatal_error("Error parsing inline asm\n");
135}
136
137
138/// EmitInlineAsm - This method formats and emits the specified machine
139/// instruction that is an inline asm.
140void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
141  assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
142
143  unsigned NumOperands = MI->getNumOperands();
144
145  // Count the number of register definitions to find the asm string.
146  unsigned NumDefs = 0;
147  for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
148       ++NumDefs)
149    assert(NumDefs != NumOperands-2 && "No asm string?");
150
151  assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
152
153  // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
154  const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
155
156  // If this asmstr is empty, just print the #APP/#NOAPP markers.
157  // These are useful to see where empty asm's wound up.
158  if (AsmStr[0] == 0) {
159    // Don't emit the comments if writing to a .o file.
160    if (!OutStreamer.hasRawTextSupport()) return;
161
162    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
163                            MAI->getInlineAsmStart());
164    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
165                            MAI->getInlineAsmEnd());
166    return;
167  }
168
169  // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
170  // enabled, so we use EmitRawText.
171  if (OutStreamer.hasRawTextSupport())
172    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
173                            MAI->getInlineAsmStart());
174
175  // Get the !srcloc metadata node if we have it, and decode the loc cookie from
176  // it.
177  unsigned LocCookie = 0;
178  const MDNode *LocMD = 0;
179  for (unsigned i = MI->getNumOperands(); i != 0; --i) {
180    if (MI->getOperand(i-1).isMetadata() &&
181        (LocMD = MI->getOperand(i-1).getMetadata()) &&
182        LocMD->getNumOperands() != 0) {
183      if (const ConstantInt *CI = dyn_cast<ConstantInt>(LocMD->getOperand(0))) {
184        LocCookie = CI->getZExtValue();
185        break;
186      }
187    }
188  }
189
190  // Emit the inline asm to a temporary string so we can emit it through
191  // EmitInlineAsm.
192  SmallString<256> StringData;
193  raw_svector_ostream OS(StringData);
194
195  OS << '\t';
196
197  // The variant of the current asmprinter.
198  int AsmPrinterVariant = MAI->getAssemblerDialect();
199
200  int CurVariant = -1;            // The number of the {.|.|.} region we are in.
201  const char *LastEmitted = AsmStr; // One past the last character emitted.
202
203  while (*LastEmitted) {
204    switch (*LastEmitted) {
205    default: {
206      // Not a special case, emit the string section literally.
207      const char *LiteralEnd = LastEmitted+1;
208      while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
209             *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
210        ++LiteralEnd;
211      if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
212        OS.write(LastEmitted, LiteralEnd-LastEmitted);
213      LastEmitted = LiteralEnd;
214      break;
215    }
216    case '\n':
217      ++LastEmitted;   // Consume newline character.
218      OS << '\n';      // Indent code with newline.
219      break;
220    case '$': {
221      ++LastEmitted;   // Consume '$' character.
222      bool Done = true;
223
224      // Handle escapes.
225      switch (*LastEmitted) {
226      default: Done = false; break;
227      case '$':     // $$ -> $
228        if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
229          OS << '$';
230        ++LastEmitted;  // Consume second '$' character.
231        break;
232      case '(':             // $( -> same as GCC's { character.
233        ++LastEmitted;      // Consume '(' character.
234        if (CurVariant != -1)
235          report_fatal_error("Nested variants found in inline asm string: '" +
236                             Twine(AsmStr) + "'");
237        CurVariant = 0;     // We're in the first variant now.
238        break;
239      case '|':
240        ++LastEmitted;  // consume '|' character.
241        if (CurVariant == -1)
242          OS << '|';       // this is gcc's behavior for | outside a variant
243        else
244          ++CurVariant;   // We're in the next variant.
245        break;
246      case ')':         // $) -> same as GCC's } char.
247        ++LastEmitted;  // consume ')' character.
248        if (CurVariant == -1)
249          OS << '}';     // this is gcc's behavior for } outside a variant
250        else
251          CurVariant = -1;
252        break;
253      }
254      if (Done) break;
255
256      bool HasCurlyBraces = false;
257      if (*LastEmitted == '{') {     // ${variable}
258        ++LastEmitted;               // Consume '{' character.
259        HasCurlyBraces = true;
260      }
261
262      // If we have ${:foo}, then this is not a real operand reference, it is a
263      // "magic" string reference, just like in .td files.  Arrange to call
264      // PrintSpecial.
265      if (HasCurlyBraces && *LastEmitted == ':') {
266        ++LastEmitted;
267        const char *StrStart = LastEmitted;
268        const char *StrEnd = strchr(StrStart, '}');
269        if (StrEnd == 0)
270          report_fatal_error("Unterminated ${:foo} operand in inline asm"
271                             " string: '" + Twine(AsmStr) + "'");
272
273        std::string Val(StrStart, StrEnd);
274        PrintSpecial(MI, OS, Val.c_str());
275        LastEmitted = StrEnd+1;
276        break;
277      }
278
279      const char *IDStart = LastEmitted;
280      const char *IDEnd = IDStart;
281      while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
282
283      unsigned Val;
284      if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
285        report_fatal_error("Bad $ operand number in inline asm string: '" +
286                           Twine(AsmStr) + "'");
287      LastEmitted = IDEnd;
288
289      char Modifier[2] = { 0, 0 };
290
291      if (HasCurlyBraces) {
292        // If we have curly braces, check for a modifier character.  This
293        // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
294        if (*LastEmitted == ':') {
295          ++LastEmitted;    // Consume ':' character.
296          if (*LastEmitted == 0)
297            report_fatal_error("Bad ${:} expression in inline asm string: '" +
298                               Twine(AsmStr) + "'");
299
300          Modifier[0] = *LastEmitted;
301          ++LastEmitted;    // Consume modifier character.
302        }
303
304        if (*LastEmitted != '}')
305          report_fatal_error("Bad ${} expression in inline asm string: '" +
306                             Twine(AsmStr) + "'");
307        ++LastEmitted;    // Consume '}' character.
308      }
309
310      if (Val >= NumOperands-1)
311        report_fatal_error("Invalid $ operand number in inline asm string: '" +
312                           Twine(AsmStr) + "'");
313
314      // Okay, we finally have a value number.  Ask the target to print this
315      // operand!
316      if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
317        unsigned OpNo = InlineAsm::MIOp_FirstOperand;
318
319        bool Error = false;
320
321        // Scan to find the machine operand number for the operand.
322        for (; Val; --Val) {
323          if (OpNo >= MI->getNumOperands()) break;
324          unsigned OpFlags = MI->getOperand(OpNo).getImm();
325          OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
326        }
327
328        if (OpNo >= MI->getNumOperands()) {
329          Error = true;
330        } else {
331          unsigned OpFlags = MI->getOperand(OpNo).getImm();
332          ++OpNo;  // Skip over the ID number.
333
334          if (Modifier[0] == 'l')  // labels are target independent
335            // FIXME: What if the operand isn't an MBB, report error?
336            OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
337          else {
338            AsmPrinter *AP = const_cast<AsmPrinter*>(this);
339            if (InlineAsm::isMemKind(OpFlags)) {
340              Error = AP->PrintAsmMemoryOperand(MI, OpNo, AsmPrinterVariant,
341                                                Modifier[0] ? Modifier : 0,
342                                                OS);
343            } else {
344              Error = AP->PrintAsmOperand(MI, OpNo, AsmPrinterVariant,
345                                          Modifier[0] ? Modifier : 0, OS);
346            }
347          }
348        }
349        if (Error) {
350          std::string msg;
351          raw_string_ostream Msg(msg);
352          Msg << "invalid operand in inline asm: '" << AsmStr << "'";
353          MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
354        }
355      }
356      break;
357    }
358    }
359  }
360  OS << '\n' << (char)0;  // null terminate string.
361  EmitInlineAsm(OS.str(), LocMD);
362
363  // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
364  // enabled, so we use EmitRawText.
365  if (OutStreamer.hasRawTextSupport())
366    OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
367                            MAI->getInlineAsmEnd());
368}
369
370
371/// PrintSpecial - Print information related to the specified machine instr
372/// that is independent of the operand, and may be independent of the instr
373/// itself.  This can be useful for portably encoding the comment character
374/// or other bits of target-specific knowledge into the asmstrings.  The
375/// syntax used is ${:comment}.  Targets can override this to add support
376/// for their own strange codes.
377void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
378                              const char *Code) const {
379  if (!strcmp(Code, "private")) {
380    OS << MAI->getPrivateGlobalPrefix();
381  } else if (!strcmp(Code, "comment")) {
382    OS << MAI->getCommentString();
383  } else if (!strcmp(Code, "uid")) {
384    // Comparing the address of MI isn't sufficient, because machineinstrs may
385    // be allocated to the same address across functions.
386
387    // If this is a new LastFn instruction, bump the counter.
388    if (LastMI != MI || LastFn != getFunctionNumber()) {
389      ++Counter;
390      LastMI = MI;
391      LastFn = getFunctionNumber();
392    }
393    OS << Counter;
394  } else {
395    std::string msg;
396    raw_string_ostream Msg(msg);
397    Msg << "Unknown special formatter '" << Code
398         << "' for machine instr: " << *MI;
399    report_fatal_error(Msg.str());
400  }
401}
402
403/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
404/// instruction, using the specified assembler variant.  Targets should
405/// override this to format as appropriate.
406bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
407                                 unsigned AsmVariant, const char *ExtraCode,
408                                 raw_ostream &O) {
409  // Target doesn't support this yet!
410  return true;
411}
412
413bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
414                                       unsigned AsmVariant,
415                                       const char *ExtraCode, raw_ostream &O) {
416  // Target doesn't support this yet!
417  return true;
418}
419
420