1//===-- AsmPrinterInlineAsm.cpp - AsmPrinter Inline Asm Handling ----------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the inline assembler pieces of the AsmPrinter class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/ADT/SmallString.h"
14#include "llvm/ADT/Twine.h"
15#include "llvm/CodeGen/AsmPrinter.h"
16#include "llvm/CodeGen/MachineBasicBlock.h"
17#include "llvm/CodeGen/MachineFunction.h"
18#include "llvm/CodeGen/MachineModuleInfo.h"
19#include "llvm/CodeGen/TargetInstrInfo.h"
20#include "llvm/CodeGen/TargetRegisterInfo.h"
21#include "llvm/IR/Constants.h"
22#include "llvm/IR/DataLayout.h"
23#include "llvm/IR/InlineAsm.h"
24#include "llvm/IR/LLVMContext.h"
25#include "llvm/IR/Module.h"
26#include "llvm/MC/MCAsmInfo.h"
27#include "llvm/MC/MCParser/MCTargetAsmParser.h"
28#include "llvm/MC/MCStreamer.h"
29#include "llvm/MC/MCSubtargetInfo.h"
30#include "llvm/MC/MCSymbol.h"
31#include "llvm/Support/ErrorHandling.h"
32#include "llvm/Support/MemoryBuffer.h"
33#include "llvm/Support/SourceMgr.h"
34#include "llvm/Support/TargetRegistry.h"
35#include "llvm/Support/raw_ostream.h"
36#include "llvm/Target/TargetMachine.h"
37using namespace llvm;
38
39#define DEBUG_TYPE "asm-printer"
40
41/// srcMgrDiagHandler - This callback is invoked when the SourceMgr for an
42/// inline asm has an error in it.  diagInfo is a pointer to the SrcMgrDiagInfo
43/// struct above.
44static void srcMgrDiagHandler(const SMDiagnostic &Diag, void *diagInfo) {
45  AsmPrinter::SrcMgrDiagInfo *DiagInfo =
46      static_cast<AsmPrinter::SrcMgrDiagInfo *>(diagInfo);
47  assert(DiagInfo && "Diagnostic context not passed down?");
48
49  // Look up a LocInfo for the buffer this diagnostic is coming from.
50  unsigned BufNum = DiagInfo->SrcMgr.FindBufferContainingLoc(Diag.getLoc());
51  const MDNode *LocInfo = nullptr;
52  if (BufNum > 0 && BufNum <= DiagInfo->LocInfos.size())
53    LocInfo = DiagInfo->LocInfos[BufNum-1];
54
55  // If the inline asm had metadata associated with it, pull out a location
56  // cookie corresponding to which line the error occurred on.
57  unsigned LocCookie = 0;
58  if (LocInfo) {
59    unsigned ErrorLine = Diag.getLineNo()-1;
60    if (ErrorLine >= LocInfo->getNumOperands())
61      ErrorLine = 0;
62
63    if (LocInfo->getNumOperands() != 0)
64      if (const ConstantInt *CI =
65              mdconst::dyn_extract<ConstantInt>(LocInfo->getOperand(ErrorLine)))
66        LocCookie = CI->getZExtValue();
67  }
68
69  DiagInfo->DiagHandler(Diag, DiagInfo->DiagContext, LocCookie);
70}
71
72unsigned AsmPrinter::addInlineAsmDiagBuffer(StringRef AsmStr,
73                                            const MDNode *LocMDNode) const {
74  if (!DiagInfo) {
75    DiagInfo = std::make_unique<SrcMgrDiagInfo>();
76
77    MCContext &Context = MMI->getContext();
78    Context.setInlineSourceManager(&DiagInfo->SrcMgr);
79
80    LLVMContext &LLVMCtx = MMI->getModule()->getContext();
81    if (LLVMCtx.getInlineAsmDiagnosticHandler()) {
82      DiagInfo->DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler();
83      DiagInfo->DiagContext = LLVMCtx.getInlineAsmDiagnosticContext();
84      DiagInfo->SrcMgr.setDiagHandler(srcMgrDiagHandler, DiagInfo.get());
85    }
86  }
87
88  SourceMgr &SrcMgr = DiagInfo->SrcMgr;
89
90  std::unique_ptr<MemoryBuffer> Buffer;
91  // The inline asm source manager will outlive AsmStr, so make a copy of the
92  // string for SourceMgr to own.
93  Buffer = MemoryBuffer::getMemBufferCopy(AsmStr, "<inline asm>");
94
95  // Tell SrcMgr about this buffer, it takes ownership of the buffer.
96  unsigned BufNum = SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
97
98  // Store LocMDNode in DiagInfo, using BufNum as an identifier.
99  if (LocMDNode) {
100    DiagInfo->LocInfos.resize(BufNum);
101    DiagInfo->LocInfos[BufNum - 1] = LocMDNode;
102  }
103
104  return BufNum;
105}
106
107
108/// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
109void AsmPrinter::EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
110                               const MCTargetOptions &MCOptions,
111                               const MDNode *LocMDNode,
112                               InlineAsm::AsmDialect Dialect) const {
113  assert(!Str.empty() && "Can't emit empty inline asm block");
114
115  // Remember if the buffer is nul terminated or not so we can avoid a copy.
116  bool isNullTerminated = Str.back() == 0;
117  if (isNullTerminated)
118    Str = Str.substr(0, Str.size()-1);
119
120  // If the output streamer does not have mature MC support or the integrated
121  // assembler has been disabled, just emit the blob textually.
122  // Otherwise parse the asm and emit it via MC support.
123  // This is useful in case the asm parser doesn't handle something but the
124  // system assembler does.
125  const MCAsmInfo *MCAI = TM.getMCAsmInfo();
126  assert(MCAI && "No MCAsmInfo");
127  if (!MCAI->useIntegratedAssembler() &&
128      !OutStreamer->isIntegratedAssemblerRequired()) {
129    emitInlineAsmStart();
130    OutStreamer->EmitRawText(Str);
131    emitInlineAsmEnd(STI, nullptr);
132    return;
133  }
134
135  unsigned BufNum = addInlineAsmDiagBuffer(Str, LocMDNode);
136  DiagInfo->SrcMgr.setIncludeDirs(MCOptions.IASSearchPaths);
137
138  std::unique_ptr<MCAsmParser> Parser(createMCAsmParser(
139          DiagInfo->SrcMgr, OutContext, *OutStreamer, *MAI, BufNum));
140
141  // Do not use assembler-level information for parsing inline assembly.
142  OutStreamer->setUseAssemblerInfoForParsing(false);
143
144  // We create a new MCInstrInfo here since we might be at the module level
145  // and not have a MachineFunction to initialize the TargetInstrInfo from and
146  // we only need MCInstrInfo for asm parsing. We create one unconditionally
147  // because it's not subtarget dependent.
148  std::unique_ptr<MCInstrInfo> MII(TM.getTarget().createMCInstrInfo());
149  std::unique_ptr<MCTargetAsmParser> TAP(TM.getTarget().createMCAsmParser(
150      STI, *Parser, *MII, MCOptions));
151  if (!TAP)
152    report_fatal_error("Inline asm not supported by this streamer because"
153                       " we don't have an asm parser for this target\n");
154  Parser->setAssemblerDialect(Dialect);
155  Parser->setTargetParser(*TAP.get());
156  // Enable lexing Masm binary and hex integer literals in intel inline
157  // assembly.
158  if (Dialect == InlineAsm::AD_Intel)
159    Parser->getLexer().setLexMasmIntegers(true);
160
161  emitInlineAsmStart();
162  // Don't implicitly switch to the text section before the asm.
163  int Res = Parser->Run(/*NoInitialTextSection*/ true,
164                        /*NoFinalize*/ true);
165  emitInlineAsmEnd(STI, &TAP->getSTI());
166
167  if (Res && !DiagInfo->DiagHandler)
168    report_fatal_error("Error parsing inline asm\n");
169}
170
171static void EmitMSInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
172                               MachineModuleInfo *MMI, AsmPrinter *AP,
173                               unsigned LocCookie, raw_ostream &OS) {
174  // Switch to the inline assembly variant.
175  OS << "\t.intel_syntax\n\t";
176
177  const char *LastEmitted = AsmStr; // One past the last character emitted.
178  unsigned NumOperands = MI->getNumOperands();
179
180  while (*LastEmitted) {
181    switch (*LastEmitted) {
182    default: {
183      // Not a special case, emit the string section literally.
184      const char *LiteralEnd = LastEmitted+1;
185      while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
186             *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
187        ++LiteralEnd;
188
189      OS.write(LastEmitted, LiteralEnd-LastEmitted);
190      LastEmitted = LiteralEnd;
191      break;
192    }
193    case '\n':
194      ++LastEmitted;   // Consume newline character.
195      OS << '\n';      // Indent code with newline.
196      break;
197    case '$': {
198      ++LastEmitted;   // Consume '$' character.
199      bool Done = true;
200
201      // Handle escapes.
202      switch (*LastEmitted) {
203      default: Done = false; break;
204      case '$':
205        ++LastEmitted;  // Consume second '$' character.
206        break;
207      }
208      if (Done) break;
209
210      bool HasCurlyBraces = false;
211      if (*LastEmitted == '{') {     // ${variable}
212        ++LastEmitted;               // Consume '{' character.
213        HasCurlyBraces = true;
214      }
215
216      // If we have ${:foo}, then this is not a real operand reference, it is a
217      // "magic" string reference, just like in .td files.  Arrange to call
218      // PrintSpecial.
219      if (HasCurlyBraces && LastEmitted[0] == ':') {
220        ++LastEmitted;
221        const char *StrStart = LastEmitted;
222        const char *StrEnd = strchr(StrStart, '}');
223        if (!StrEnd)
224          report_fatal_error("Unterminated ${:foo} operand in inline asm"
225                             " string: '" + Twine(AsmStr) + "'");
226
227        std::string Val(StrStart, StrEnd);
228        AP->PrintSpecial(MI, OS, Val.c_str());
229        LastEmitted = StrEnd+1;
230        break;
231      }
232
233      const char *IDStart = LastEmitted;
234      const char *IDEnd = IDStart;
235      while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
236
237      unsigned Val;
238      if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
239        report_fatal_error("Bad $ operand number in inline asm string: '" +
240                           Twine(AsmStr) + "'");
241      LastEmitted = IDEnd;
242
243      if (Val >= NumOperands-1)
244        report_fatal_error("Invalid $ operand number in inline asm string: '" +
245                           Twine(AsmStr) + "'");
246
247      char Modifier[2] = { 0, 0 };
248
249      if (HasCurlyBraces) {
250        // If we have curly braces, check for a modifier character.  This
251        // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
252        if (*LastEmitted == ':') {
253          ++LastEmitted;    // Consume ':' character.
254          if (*LastEmitted == 0)
255            report_fatal_error("Bad ${:} expression in inline asm string: '" +
256                               Twine(AsmStr) + "'");
257
258          Modifier[0] = *LastEmitted;
259          ++LastEmitted;    // Consume modifier character.
260        }
261
262        if (*LastEmitted != '}')
263          report_fatal_error("Bad ${} expression in inline asm string: '" +
264                             Twine(AsmStr) + "'");
265        ++LastEmitted;    // Consume '}' character.
266      }
267
268      // Okay, we finally have a value number.  Ask the target to print this
269      // operand!
270      unsigned OpNo = InlineAsm::MIOp_FirstOperand;
271
272      bool Error = false;
273
274      // Scan to find the machine operand number for the operand.
275      for (; Val; --Val) {
276        if (OpNo >= MI->getNumOperands()) break;
277        unsigned OpFlags = MI->getOperand(OpNo).getImm();
278        OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
279      }
280
281      // We may have a location metadata attached to the end of the
282      // instruction, and at no point should see metadata at any
283      // other point while processing. It's an error if so.
284      if (OpNo >= MI->getNumOperands() ||
285          MI->getOperand(OpNo).isMetadata()) {
286        Error = true;
287      } else {
288        unsigned OpFlags = MI->getOperand(OpNo).getImm();
289        ++OpNo;  // Skip over the ID number.
290
291        if (InlineAsm::isMemKind(OpFlags)) {
292          Error = AP->PrintAsmMemoryOperand(
293              MI, OpNo, Modifier[0] ? Modifier : nullptr, OS);
294        } else {
295          Error = AP->PrintAsmOperand(MI, OpNo,
296                                      Modifier[0] ? Modifier : nullptr, OS);
297        }
298      }
299      if (Error) {
300        std::string msg;
301        raw_string_ostream Msg(msg);
302        Msg << "invalid operand in inline asm: '" << AsmStr << "'";
303        MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
304      }
305      break;
306    }
307    }
308  }
309  OS << "\n\t.att_syntax\n" << (char)0;  // null terminate string.
310}
311
312static void EmitGCCInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
313                                MachineModuleInfo *MMI, int AsmPrinterVariant,
314                                AsmPrinter *AP, unsigned LocCookie,
315                                raw_ostream &OS) {
316  int CurVariant = -1;            // The number of the {.|.|.} region we are in.
317  const char *LastEmitted = AsmStr; // One past the last character emitted.
318  unsigned NumOperands = MI->getNumOperands();
319
320  OS << '\t';
321
322  while (*LastEmitted) {
323    switch (*LastEmitted) {
324    default: {
325      // Not a special case, emit the string section literally.
326      const char *LiteralEnd = LastEmitted+1;
327      while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
328             *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
329        ++LiteralEnd;
330      if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
331        OS.write(LastEmitted, LiteralEnd-LastEmitted);
332      LastEmitted = LiteralEnd;
333      break;
334    }
335    case '\n':
336      ++LastEmitted;   // Consume newline character.
337      OS << '\n';      // Indent code with newline.
338      break;
339    case '$': {
340      ++LastEmitted;   // Consume '$' character.
341      bool Done = true;
342
343      // Handle escapes.
344      switch (*LastEmitted) {
345      default: Done = false; break;
346      case '$':     // $$ -> $
347        if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
348          OS << '$';
349        ++LastEmitted;  // Consume second '$' character.
350        break;
351      case '(':             // $( -> same as GCC's { character.
352        ++LastEmitted;      // Consume '(' character.
353        if (CurVariant != -1)
354          report_fatal_error("Nested variants found in inline asm string: '" +
355                             Twine(AsmStr) + "'");
356        CurVariant = 0;     // We're in the first variant now.
357        break;
358      case '|':
359        ++LastEmitted;  // consume '|' character.
360        if (CurVariant == -1)
361          OS << '|';       // this is gcc's behavior for | outside a variant
362        else
363          ++CurVariant;   // We're in the next variant.
364        break;
365      case ')':         // $) -> same as GCC's } char.
366        ++LastEmitted;  // consume ')' character.
367        if (CurVariant == -1)
368          OS << '}';     // this is gcc's behavior for } outside a variant
369        else
370          CurVariant = -1;
371        break;
372      }
373      if (Done) break;
374
375      bool HasCurlyBraces = false;
376      if (*LastEmitted == '{') {     // ${variable}
377        ++LastEmitted;               // Consume '{' character.
378        HasCurlyBraces = true;
379      }
380
381      // If we have ${:foo}, then this is not a real operand reference, it is a
382      // "magic" string reference, just like in .td files.  Arrange to call
383      // PrintSpecial.
384      if (HasCurlyBraces && *LastEmitted == ':') {
385        ++LastEmitted;
386        const char *StrStart = LastEmitted;
387        const char *StrEnd = strchr(StrStart, '}');
388        if (!StrEnd)
389          report_fatal_error("Unterminated ${:foo} operand in inline asm"
390                             " string: '" + Twine(AsmStr) + "'");
391
392        std::string Val(StrStart, StrEnd);
393        AP->PrintSpecial(MI, OS, Val.c_str());
394        LastEmitted = StrEnd+1;
395        break;
396      }
397
398      const char *IDStart = LastEmitted;
399      const char *IDEnd = IDStart;
400      while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
401
402      unsigned Val;
403      if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
404        report_fatal_error("Bad $ operand number in inline asm string: '" +
405                           Twine(AsmStr) + "'");
406      LastEmitted = IDEnd;
407
408      char Modifier[2] = { 0, 0 };
409
410      if (HasCurlyBraces) {
411        // If we have curly braces, check for a modifier character.  This
412        // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
413        if (*LastEmitted == ':') {
414          ++LastEmitted;    // Consume ':' character.
415          if (*LastEmitted == 0)
416            report_fatal_error("Bad ${:} expression in inline asm string: '" +
417                               Twine(AsmStr) + "'");
418
419          Modifier[0] = *LastEmitted;
420          ++LastEmitted;    // Consume modifier character.
421        }
422
423        if (*LastEmitted != '}')
424          report_fatal_error("Bad ${} expression in inline asm string: '" +
425                             Twine(AsmStr) + "'");
426        ++LastEmitted;    // Consume '}' character.
427      }
428
429      if (Val >= NumOperands-1)
430        report_fatal_error("Invalid $ operand number in inline asm string: '" +
431                           Twine(AsmStr) + "'");
432
433      // Okay, we finally have a value number.  Ask the target to print this
434      // operand!
435      if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
436        unsigned OpNo = InlineAsm::MIOp_FirstOperand;
437
438        bool Error = false;
439
440        // Scan to find the machine operand number for the operand.
441        for (; Val; --Val) {
442          if (OpNo >= MI->getNumOperands()) break;
443          unsigned OpFlags = MI->getOperand(OpNo).getImm();
444          OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
445        }
446
447        // We may have a location metadata attached to the end of the
448        // instruction, and at no point should see metadata at any
449        // other point while processing. It's an error if so.
450        if (OpNo >= MI->getNumOperands() ||
451            MI->getOperand(OpNo).isMetadata()) {
452          Error = true;
453        } else {
454          unsigned OpFlags = MI->getOperand(OpNo).getImm();
455          ++OpNo;  // Skip over the ID number.
456
457          // FIXME: Shouldn't arch-independent output template handling go into
458          // PrintAsmOperand?
459          // Labels are target independent.
460          if (MI->getOperand(OpNo).isBlockAddress()) {
461            const BlockAddress *BA = MI->getOperand(OpNo).getBlockAddress();
462            MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
463            Sym->print(OS, AP->MAI);
464            MMI->getContext().registerInlineAsmLabel(Sym);
465          } else if (MI->getOperand(OpNo).isMBB()) {
466            const MCSymbol *Sym = MI->getOperand(OpNo).getMBB()->getSymbol();
467            Sym->print(OS, AP->MAI);
468          } else if (Modifier[0] == 'l') {
469            Error = true;
470          } else if (InlineAsm::isMemKind(OpFlags)) {
471            Error = AP->PrintAsmMemoryOperand(
472                MI, OpNo, Modifier[0] ? Modifier : nullptr, OS);
473          } else {
474            Error = AP->PrintAsmOperand(MI, OpNo,
475                                        Modifier[0] ? Modifier : nullptr, OS);
476          }
477        }
478        if (Error) {
479          std::string msg;
480          raw_string_ostream Msg(msg);
481          Msg << "invalid operand in inline asm: '" << AsmStr << "'";
482          MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
483        }
484      }
485      break;
486    }
487    }
488  }
489  OS << '\n' << (char)0;  // null terminate string.
490}
491
492/// EmitInlineAsm - This method formats and emits the specified machine
493/// instruction that is an inline asm.
494void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
495  assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
496
497  // Count the number of register definitions to find the asm string.
498  unsigned NumDefs = 0;
499  for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
500       ++NumDefs)
501    assert(NumDefs != MI->getNumOperands()-2 && "No asm string?");
502
503  assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
504
505  // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
506  const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
507
508  // If this asmstr is empty, just print the #APP/#NOAPP markers.
509  // These are useful to see where empty asm's wound up.
510  if (AsmStr[0] == 0) {
511    OutStreamer->emitRawComment(MAI->getInlineAsmStart());
512    OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
513    return;
514  }
515
516  // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
517  // enabled, so we use emitRawComment.
518  OutStreamer->emitRawComment(MAI->getInlineAsmStart());
519
520  // Get the !srcloc metadata node if we have it, and decode the loc cookie from
521  // it.
522  unsigned LocCookie = 0;
523  const MDNode *LocMD = nullptr;
524  for (unsigned i = MI->getNumOperands(); i != 0; --i) {
525    if (MI->getOperand(i-1).isMetadata() &&
526        (LocMD = MI->getOperand(i-1).getMetadata()) &&
527        LocMD->getNumOperands() != 0) {
528      if (const ConstantInt *CI =
529              mdconst::dyn_extract<ConstantInt>(LocMD->getOperand(0))) {
530        LocCookie = CI->getZExtValue();
531        break;
532      }
533    }
534  }
535
536  // Emit the inline asm to a temporary string so we can emit it through
537  // EmitInlineAsm.
538  SmallString<256> StringData;
539  raw_svector_ostream OS(StringData);
540
541  // The variant of the current asmprinter.
542  int AsmPrinterVariant = MAI->getAssemblerDialect();
543  AsmPrinter *AP = const_cast<AsmPrinter*>(this);
544  if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
545    EmitGCCInlineAsmStr(AsmStr, MI, MMI, AsmPrinterVariant, AP, LocCookie, OS);
546  else
547    EmitMSInlineAsmStr(AsmStr, MI, MMI, AP, LocCookie, OS);
548
549  // Emit warnings if we use reserved registers on the clobber list, as
550  // that might give surprising results.
551  std::vector<std::string> RestrRegs;
552  // Start with the first operand descriptor, and iterate over them.
553  for (unsigned I = InlineAsm::MIOp_FirstOperand, NumOps = MI->getNumOperands();
554       I < NumOps; ++I) {
555    const MachineOperand &MO = MI->getOperand(I);
556    if (MO.isImm()) {
557      unsigned Flags = MO.getImm();
558      const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
559      if (InlineAsm::getKind(Flags) == InlineAsm::Kind_Clobber &&
560          !TRI->isAsmClobberable(*MF, MI->getOperand(I + 1).getReg())) {
561        RestrRegs.push_back(TRI->getName(MI->getOperand(I + 1).getReg()));
562      }
563      // Skip to one before the next operand descriptor, if it exists.
564      I += InlineAsm::getNumOperandRegisters(Flags);
565    }
566  }
567
568  if (!RestrRegs.empty()) {
569    unsigned BufNum = addInlineAsmDiagBuffer(OS.str(), LocMD);
570    auto &SrcMgr = DiagInfo->SrcMgr;
571    SMLoc Loc = SMLoc::getFromPointer(
572        SrcMgr.getMemoryBuffer(BufNum)->getBuffer().begin());
573
574    std::string Msg = "inline asm clobber list contains reserved registers: ";
575    for (auto I = RestrRegs.begin(), E = RestrRegs.end(); I != E; I++) {
576      if(I != RestrRegs.begin())
577        Msg += ", ";
578      Msg += *I;
579    }
580    std::string Note = "Reserved registers on the clobber list may not be "
581                "preserved across the asm statement, and clobbering them may "
582                "lead to undefined behaviour.";
583    SrcMgr.PrintMessage(Loc, SourceMgr::DK_Warning, Msg);
584    SrcMgr.PrintMessage(Loc, SourceMgr::DK_Note, Note);
585  }
586
587  EmitInlineAsm(OS.str(), getSubtargetInfo(), TM.Options.MCOptions, LocMD,
588                MI->getInlineAsmDialect());
589
590  // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
591  // enabled, so we use emitRawComment.
592  OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
593}
594
595
596/// PrintSpecial - Print information related to the specified machine instr
597/// that is independent of the operand, and may be independent of the instr
598/// itself.  This can be useful for portably encoding the comment character
599/// or other bits of target-specific knowledge into the asmstrings.  The
600/// syntax used is ${:comment}.  Targets can override this to add support
601/// for their own strange codes.
602void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
603                              const char *Code) const {
604  if (!strcmp(Code, "private")) {
605    const DataLayout &DL = MF->getDataLayout();
606    OS << DL.getPrivateGlobalPrefix();
607  } else if (!strcmp(Code, "comment")) {
608    OS << MAI->getCommentString();
609  } else if (!strcmp(Code, "uid")) {
610    // Comparing the address of MI isn't sufficient, because machineinstrs may
611    // be allocated to the same address across functions.
612
613    // If this is a new LastFn instruction, bump the counter.
614    if (LastMI != MI || LastFn != getFunctionNumber()) {
615      ++Counter;
616      LastMI = MI;
617      LastFn = getFunctionNumber();
618    }
619    OS << Counter;
620  } else {
621    std::string msg;
622    raw_string_ostream Msg(msg);
623    Msg << "Unknown special formatter '" << Code
624         << "' for machine instr: " << *MI;
625    report_fatal_error(Msg.str());
626  }
627}
628
629void AsmPrinter::PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS) {
630  assert(MO.isGlobal() && "caller should check MO.isGlobal");
631  getSymbol(MO.getGlobal())->print(OS, MAI);
632  printOffset(MO.getOffset(), OS);
633}
634
635/// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
636/// instruction, using the specified assembler variant.  Targets should
637/// override this to format as appropriate for machine specific ExtraCodes
638/// or when the arch-independent handling would be too complex otherwise.
639bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
640                                 const char *ExtraCode, raw_ostream &O) {
641  // Does this asm operand have a single letter operand modifier?
642  if (ExtraCode && ExtraCode[0]) {
643    if (ExtraCode[1] != 0) return true; // Unknown modifier.
644
645    // https://gcc.gnu.org/onlinedocs/gccint/Output-Template.html
646    const MachineOperand &MO = MI->getOperand(OpNo);
647    switch (ExtraCode[0]) {
648    default:
649      return true;  // Unknown modifier.
650    case 'a': // Print as memory address.
651      if (MO.isReg()) {
652        PrintAsmMemoryOperand(MI, OpNo, nullptr, O);
653        return false;
654      }
655      LLVM_FALLTHROUGH; // GCC allows '%a' to behave like '%c' with immediates.
656    case 'c': // Substitute immediate value without immediate syntax
657      if (MO.isImm()) {
658        O << MO.getImm();
659        return false;
660      }
661      if (MO.isGlobal()) {
662        PrintSymbolOperand(MO, O);
663        return false;
664      }
665      return true;
666    case 'n':  // Negate the immediate constant.
667      if (!MO.isImm())
668        return true;
669      O << -MO.getImm();
670      return false;
671    case 's':  // The GCC deprecated s modifier
672      if (!MO.isImm())
673        return true;
674      O << ((32 - MO.getImm()) & 31);
675      return false;
676    }
677  }
678  return true;
679}
680
681bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
682                                       const char *ExtraCode, raw_ostream &O) {
683  // Target doesn't support this yet!
684  return true;
685}
686
687void AsmPrinter::emitInlineAsmStart() const {}
688
689void AsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
690                                  const MCSubtargetInfo *EndInfo) const {}
691