lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

   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"
  37 using 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.
  44 static 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
  72 unsigned 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.
 109 void 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
 171 static 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       // If we have ${:foo}, then this is not a real operand reference, it is a
 211       // "magic" string reference, just like in .td files.  Arrange to call
 212       // PrintSpecial.
 213       if (LastEmitted[0] == '{' && LastEmitted[1] == ':') {
 214         LastEmitted += 2;
 215         const char *StrStart = LastEmitted;
 216         const char *StrEnd = strchr(StrStart, '}');
 217         if (!StrEnd)
 218           report_fatal_error("Unterminated ${:foo} operand in inline asm"
 219                              " string: '" + Twine(AsmStr) + "'");
 220
 221         std::string Val(StrStart, StrEnd);
 222         AP->PrintSpecial(MI, OS, Val.c_str());
 223         LastEmitted = StrEnd+1;
 224         break;
 225       }
 226
 227       const char *IDStart = LastEmitted;
 228       const char *IDEnd = IDStart;
 229       while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
 230
 231       unsigned Val;
 232       if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
 233         report_fatal_error("Bad $ operand number in inline asm string: '" +
 234                            Twine(AsmStr) + "'");
 235       LastEmitted = IDEnd;
 236
 237       if (Val >= NumOperands-1)
 238         report_fatal_error("Invalid $ operand number in inline asm string: '" +
 239                            Twine(AsmStr) + "'");
 240
 241       // Okay, we finally have a value number.  Ask the target to print this
 242       // operand!
 243       unsigned OpNo = InlineAsm::MIOp_FirstOperand;
 244
 245       bool Error = false;
 246
 247       // Scan to find the machine operand number for the operand.
 248       for (; Val; --Val) {
 249         if (OpNo >= MI->getNumOperands()) break;
 250         unsigned OpFlags = MI->getOperand(OpNo).getImm();
 251         OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
 252       }
 253
 254       // We may have a location metadata attached to the end of the
 255       // instruction, and at no point should see metadata at any
 256       // other point while processing. It's an error if so.
 257       if (OpNo >= MI->getNumOperands() ||
 258           MI->getOperand(OpNo).isMetadata()) {
 259         Error = true;
 260       } else {
 261         unsigned OpFlags = MI->getOperand(OpNo).getImm();
 262         ++OpNo;  // Skip over the ID number.
 263
 264         if (InlineAsm::isMemKind(OpFlags)) {
 265           Error = AP->PrintAsmMemoryOperand(MI, OpNo, /*Modifier*/ nullptr, OS);
 266         } else {
 267           Error = AP->PrintAsmOperand(MI, OpNo, /*Modifier*/ nullptr, OS);
 268         }
 269       }
 270       if (Error) {
 271         std::string msg;
 272         raw_string_ostream Msg(msg);
 273         Msg << "invalid operand in inline asm: '" << AsmStr << "'";
 274         MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
 275       }
 276       break;
 277     }
 278     }
 279   }
 280   OS << "\n\t.att_syntax\n" << (char)0;  // null terminate string.
 281 }
 282
 283 static void EmitGCCInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
 284                                 MachineModuleInfo *MMI, int AsmPrinterVariant,
 285                                 AsmPrinter *AP, unsigned LocCookie,
 286                                 raw_ostream &OS) {
 287   int CurVariant = -1;            // The number of the {.|.|.} region we are in.
 288   const char *LastEmitted = AsmStr; // One past the last character emitted.
 289   unsigned NumOperands = MI->getNumOperands();
 290
 291   OS << '\t';
 292
 293   while (*LastEmitted) {
 294     switch (*LastEmitted) {
 295     default: {
 296       // Not a special case, emit the string section literally.
 297       const char *LiteralEnd = LastEmitted+1;
 298       while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
 299              *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
 300         ++LiteralEnd;
 301       if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
 302         OS.write(LastEmitted, LiteralEnd-LastEmitted);
 303       LastEmitted = LiteralEnd;
 304       break;
 305     }
 306     case '\n':
 307       ++LastEmitted;   // Consume newline character.
 308       OS << '\n';      // Indent code with newline.
 309       break;
 310     case '$': {
 311       ++LastEmitted;   // Consume '$' character.
 312       bool Done = true;
 313
 314       // Handle escapes.
 315       switch (*LastEmitted) {
 316       default: Done = false; break;
 317       case '$':     // $$ -> $
 318         if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
 319           OS << '$';
 320         ++LastEmitted;  // Consume second '$' character.
 321         break;
 322       case '(':             // $( -> same as GCC's { character.
 323         ++LastEmitted;      // Consume '(' character.
 324         if (CurVariant != -1)
 325           report_fatal_error("Nested variants found in inline asm string: '" +
 326                              Twine(AsmStr) + "'");
 327         CurVariant = 0;     // We're in the first variant now.
 328         break;
 329       case '|':
 330         ++LastEmitted;  // consume '|' character.
 331         if (CurVariant == -1)
 332           OS << '|';       // this is gcc's behavior for | outside a variant
 333         else
 334           ++CurVariant;   // We're in the next variant.
 335         break;
 336       case ')':         // $) -> same as GCC's } char.
 337         ++LastEmitted;  // consume ')' character.
 338         if (CurVariant == -1)
 339           OS << '}';     // this is gcc's behavior for } outside a variant
 340         else
 341           CurVariant = -1;
 342         break;
 343       }
 344       if (Done) break;
 345
 346       bool HasCurlyBraces = false;
 347       if (*LastEmitted == '{') {     // ${variable}
 348         ++LastEmitted;               // Consume '{' character.
 349         HasCurlyBraces = true;
 350       }
 351
 352       // If we have ${:foo}, then this is not a real operand reference, it is a
 353       // "magic" string reference, just like in .td files.  Arrange to call
 354       // PrintSpecial.
 355       if (HasCurlyBraces && *LastEmitted == ':') {
 356         ++LastEmitted;
 357         const char *StrStart = LastEmitted;
 358         const char *StrEnd = strchr(StrStart, '}');
 359         if (!StrEnd)
 360           report_fatal_error("Unterminated ${:foo} operand in inline asm"
 361                              " string: '" + Twine(AsmStr) + "'");
 362
 363         std::string Val(StrStart, StrEnd);
 364         AP->PrintSpecial(MI, OS, Val.c_str());
 365         LastEmitted = StrEnd+1;
 366         break;
 367       }
 368
 369       const char *IDStart = LastEmitted;
 370       const char *IDEnd = IDStart;
 371       while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
 372
 373       unsigned Val;
 374       if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
 375         report_fatal_error("Bad $ operand number in inline asm string: '" +
 376                            Twine(AsmStr) + "'");
 377       LastEmitted = IDEnd;
 378
 379       char Modifier[2] = { 0, 0 };
 380
 381       if (HasCurlyBraces) {
 382         // If we have curly braces, check for a modifier character.  This
 383         // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
 384         if (*LastEmitted == ':') {
 385           ++LastEmitted;    // Consume ':' character.
 386           if (*LastEmitted == 0)
 387             report_fatal_error("Bad ${:} expression in inline asm string: '" +
 388                                Twine(AsmStr) + "'");
 389
 390           Modifier[0] = *LastEmitted;
 391           ++LastEmitted;    // Consume modifier character.
 392         }
 393
 394         if (*LastEmitted != '}')
 395           report_fatal_error("Bad ${} expression in inline asm string: '" +
 396                              Twine(AsmStr) + "'");
 397         ++LastEmitted;    // Consume '}' character.
 398       }
 399
 400       if (Val >= NumOperands-1)
 401         report_fatal_error("Invalid $ operand number in inline asm string: '" +
 402                            Twine(AsmStr) + "'");
 403
 404       // Okay, we finally have a value number.  Ask the target to print this
 405       // operand!
 406       if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
 407         unsigned OpNo = InlineAsm::MIOp_FirstOperand;
 408
 409         bool Error = false;
 410
 411         // Scan to find the machine operand number for the operand.
 412         for (; Val; --Val) {
 413           if (OpNo >= MI->getNumOperands()) break;
 414           unsigned OpFlags = MI->getOperand(OpNo).getImm();
 415           OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
 416         }
 417
 418         // We may have a location metadata attached to the end of the
 419         // instruction, and at no point should see metadata at any
 420         // other point while processing. It's an error if so.
 421         if (OpNo >= MI->getNumOperands() ||
 422             MI->getOperand(OpNo).isMetadata()) {
 423           Error = true;
 424         } else {
 425           unsigned OpFlags = MI->getOperand(OpNo).getImm();
 426           ++OpNo;  // Skip over the ID number.
 427
 428           // FIXME: Shouldn't arch-independent output template handling go into
 429           // PrintAsmOperand?
 430           if (Modifier[0] == 'l') { // Labels are target independent.
 431             if (MI->getOperand(OpNo).isBlockAddress()) {
 432               const BlockAddress *BA = MI->getOperand(OpNo).getBlockAddress();
 433               MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
 434               Sym->print(OS, AP->MAI);
 435               MMI->getContext().registerInlineAsmLabel(Sym);
 436             } else if (MI->getOperand(OpNo).isMBB()) {
 437               const MCSymbol *Sym = MI->getOperand(OpNo).getMBB()->getSymbol();
 438               Sym->print(OS, AP->MAI);
 439             } else {
 440               Error = true;
 441             }
 442           } else {
 443             if (InlineAsm::isMemKind(OpFlags)) {
 444               Error = AP->PrintAsmMemoryOperand(
 445                   MI, OpNo, Modifier[0] ? Modifier : nullptr, OS);
 446             } else {
 447               Error = AP->PrintAsmOperand(MI, OpNo,
 448                                           Modifier[0] ? Modifier : nullptr, OS);
 449             }
 450           }
 451         }
 452         if (Error) {
 453           std::string msg;
 454           raw_string_ostream Msg(msg);
 455           Msg << "invalid operand in inline asm: '" << AsmStr << "'";
 456           MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
 457         }
 458       }
 459       break;
 460     }
 461     }
 462   }
 463   OS << '\n' << (char)0;  // null terminate string.
 464 }
 465
 466 /// EmitInlineAsm - This method formats and emits the specified machine
 467 /// instruction that is an inline asm.
 468 void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
 469   assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
 470
 471   // Count the number of register definitions to find the asm string.
 472   unsigned NumDefs = 0;
 473   for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
 474        ++NumDefs)
 475     assert(NumDefs != MI->getNumOperands()-2 && "No asm string?");
 476
 477   assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
 478
 479   // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
 480   const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
 481
 482   // If this asmstr is empty, just print the #APP/#NOAPP markers.
 483   // These are useful to see where empty asm's wound up.
 484   if (AsmStr[0] == 0) {
 485     OutStreamer->emitRawComment(MAI->getInlineAsmStart());
 486     OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
 487     return;
 488   }
 489
 490   // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
 491   // enabled, so we use emitRawComment.
 492   OutStreamer->emitRawComment(MAI->getInlineAsmStart());
 493
 494   // Get the !srcloc metadata node if we have it, and decode the loc cookie from
 495   // it.
 496   unsigned LocCookie = 0;
 497   const MDNode *LocMD = nullptr;
 498   for (unsigned i = MI->getNumOperands(); i != 0; --i) {
 499     if (MI->getOperand(i-1).isMetadata() &&
 500         (LocMD = MI->getOperand(i-1).getMetadata()) &&
 501         LocMD->getNumOperands() != 0) {
 502       if (const ConstantInt *CI =
 503               mdconst::dyn_extract<ConstantInt>(LocMD->getOperand(0))) {
 504         LocCookie = CI->getZExtValue();
 505         break;
 506       }
 507     }
 508   }
 509
 510   // Emit the inline asm to a temporary string so we can emit it through
 511   // EmitInlineAsm.
 512   SmallString<256> StringData;
 513   raw_svector_ostream OS(StringData);
 514
 515   // The variant of the current asmprinter.
 516   int AsmPrinterVariant = MAI->getAssemblerDialect();
 517   AsmPrinter *AP = const_cast<AsmPrinter*>(this);
 518   if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
 519     EmitGCCInlineAsmStr(AsmStr, MI, MMI, AsmPrinterVariant, AP, LocCookie, OS);
 520   else
 521     EmitMSInlineAsmStr(AsmStr, MI, MMI, AP, LocCookie, OS);
 522
 523   // Emit warnings if we use reserved registers on the clobber list, as
 524   // that might give surprising results.
 525   std::vector<std::string> RestrRegs;
 526   // Start with the first operand descriptor, and iterate over them.
 527   for (unsigned I = InlineAsm::MIOp_FirstOperand, NumOps = MI->getNumOperands();
 528        I < NumOps; ++I) {
 529     const MachineOperand &MO = MI->getOperand(I);
 530     if (MO.isImm()) {
 531       unsigned Flags = MO.getImm();
 532       const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
 533       if (InlineAsm::getKind(Flags) == InlineAsm::Kind_Clobber &&
 534           !TRI->isAsmClobberable(*MF, MI->getOperand(I + 1).getReg())) {
 535         RestrRegs.push_back(TRI->getName(MI->getOperand(I + 1).getReg()));
 536       }
 537       // Skip to one before the next operand descriptor, if it exists.
 538       I += InlineAsm::getNumOperandRegisters(Flags);
 539     }
 540   }
 541
 542   if (!RestrRegs.empty()) {
 543     unsigned BufNum = addInlineAsmDiagBuffer(OS.str(), LocMD);
 544     auto &SrcMgr = DiagInfo->SrcMgr;
 545     SMLoc Loc = SMLoc::getFromPointer(
 546         SrcMgr.getMemoryBuffer(BufNum)->getBuffer().begin());
 547
 548     std::string Msg = "inline asm clobber list contains reserved registers: ";
 549     for (auto I = RestrRegs.begin(), E = RestrRegs.end(); I != E; I++) {
 550       if(I != RestrRegs.begin())
 551         Msg += ", ";
 552       Msg += *I;
 553     }
 554     std::string Note = "Reserved registers on the clobber list may not be "
 555                 "preserved across the asm statement, and clobbering them may "
 556                 "lead to undefined behaviour.";
 557     SrcMgr.PrintMessage(Loc, SourceMgr::DK_Warning, Msg);
 558     SrcMgr.PrintMessage(Loc, SourceMgr::DK_Note, Note);
 559   }
 560
 561   EmitInlineAsm(OS.str(), getSubtargetInfo(), TM.Options.MCOptions, LocMD,
 562                 MI->getInlineAsmDialect());
 563
 564   // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
 565   // enabled, so we use emitRawComment.
 566   OutStreamer->emitRawComment(MAI->getInlineAsmEnd());
 567 }
 568
 569
 570 /// PrintSpecial - Print information related to the specified machine instr
 571 /// that is independent of the operand, and may be independent of the instr
 572 /// itself.  This can be useful for portably encoding the comment character
 573 /// or other bits of target-specific knowledge into the asmstrings.  The
 574 /// syntax used is ${:comment}.  Targets can override this to add support
 575 /// for their own strange codes.
 576 void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
 577                               const char *Code) const {
 578   if (!strcmp(Code, "private")) {
 579     const DataLayout &DL = MF->getDataLayout();
 580     OS << DL.getPrivateGlobalPrefix();
 581   } else if (!strcmp(Code, "comment")) {
 582     OS << MAI->getCommentString();
 583   } else if (!strcmp(Code, "uid")) {
 584     // Comparing the address of MI isn't sufficient, because machineinstrs may
 585     // be allocated to the same address across functions.
 586
 587     // If this is a new LastFn instruction, bump the counter.
 588     if (LastMI != MI || LastFn != getFunctionNumber()) {
 589       ++Counter;
 590       LastMI = MI;
 591       LastFn = getFunctionNumber();
 592     }
 593     OS << Counter;
 594   } else {
 595     std::string msg;
 596     raw_string_ostream Msg(msg);
 597     Msg << "Unknown special formatter '" << Code
 598          << "' for machine instr: " << *MI;
 599     report_fatal_error(Msg.str());
 600   }
 601 }
 602
 603 void AsmPrinter::PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS) {
 604   assert(MO.isGlobal() && "caller should check MO.isGlobal");
 605   getSymbol(MO.getGlobal())->print(OS, MAI);
 606   printOffset(MO.getOffset(), OS);
 607 }
 608
 609 /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
 610 /// instruction, using the specified assembler variant.  Targets should
 611 /// override this to format as appropriate for machine specific ExtraCodes
 612 /// or when the arch-independent handling would be too complex otherwise.
 613 bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 614                                  const char *ExtraCode, raw_ostream &O) {
 615   // Does this asm operand have a single letter operand modifier?
 616   if (ExtraCode && ExtraCode[0]) {
 617     if (ExtraCode[1] != 0) return true; // Unknown modifier.
 618
 619     // https://gcc.gnu.org/onlinedocs/gccint/Output-Template.html
 620     const MachineOperand &MO = MI->getOperand(OpNo);
 621     switch (ExtraCode[0]) {
 622     default:
 623       return true;  // Unknown modifier.
 624     case 'a': // Print as memory address.
 625       if (MO.isReg()) {
 626         PrintAsmMemoryOperand(MI, OpNo, nullptr, O);
 627         return false;
 628       }
 629       LLVM_FALLTHROUGH; // GCC allows '%a' to behave like '%c' with immediates.
 630     case 'c': // Substitute immediate value without immediate syntax
 631       if (MO.isImm()) {
 632         O << MO.getImm();
 633         return false;
 634       }
 635       if (MO.isGlobal()) {
 636         PrintSymbolOperand(MO, O);
 637         return false;
 638       }
 639       return true;
 640     case 'n':  // Negate the immediate constant.
 641       if (!MO.isImm())
 642         return true;
 643       O << -MO.getImm();
 644       return false;
 645     case 's':  // The GCC deprecated s modifier
 646       if (!MO.isImm())
 647         return true;
 648       O << ((32 - MO.getImm()) & 31);
 649       return false;
 650     }
 651   }
 652   return true;
 653 }
 654
 655 bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 656                                        const char *ExtraCode, raw_ostream &O) {
 657   // Target doesn't support this yet!
 658   return true;
 659 }
 660
 661 void AsmPrinter::emitInlineAsmStart() const {}
 662
 663 void AsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
 664                                   const MCSubtargetInfo *EndInfo) const {}