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      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 #include "llvm/CodeGen/AsmPrinter.h"
     15 #include "llvm/ADT/SmallString.h"
     16 #include "llvm/ADT/Twine.h"
     17 #include "llvm/CodeGen/MachineBasicBlock.h"
     18 #include "llvm/CodeGen/MachineFunction.h"
     19 #include "llvm/CodeGen/MachineModuleInfo.h"
     20 #include "llvm/IR/Constants.h"
     21 #include "llvm/IR/DataLayout.h"
     22 #include "llvm/IR/InlineAsm.h"
     23 #include "llvm/IR/LLVMContext.h"
     24 #include "llvm/IR/Module.h"
     25 #include "llvm/MC/MCAsmInfo.h"
     26 #include "llvm/MC/MCStreamer.h"
     27 #include "llvm/MC/MCSubtargetInfo.h"
     28 #include "llvm/MC/MCSymbol.h"
     29 #include "llvm/MC/MCTargetAsmParser.h"
     30 #include "llvm/Support/ErrorHandling.h"
     31 #include "llvm/Support/MemoryBuffer.h"
     32 #include "llvm/Support/SourceMgr.h"
     33 #include "llvm/Support/TargetRegistry.h"
     34 #include "llvm/Support/raw_ostream.h"
     35 #include "llvm/Target/TargetMachine.h"
     36 #include "llvm/Target/TargetSubtargetInfo.h"
     37 using namespace llvm;
     38 
     39 #define DEBUG_TYPE "asm-printer"
     40 
     41 namespace {
     42   struct SrcMgrDiagInfo {
     43     const MDNode *LocInfo;
     44     LLVMContext::InlineAsmDiagHandlerTy DiagHandler;
     45     void *DiagContext;
     46   };
     47 }
     48 
     49 /// srcMgrDiagHandler - This callback is invoked when the SourceMgr for an
     50 /// inline asm has an error in it.  diagInfo is a pointer to the SrcMgrDiagInfo
     51 /// struct above.
     52 static void srcMgrDiagHandler(const SMDiagnostic &Diag, void *diagInfo) {
     53   SrcMgrDiagInfo *DiagInfo = static_cast<SrcMgrDiagInfo *>(diagInfo);
     54   assert(DiagInfo && "Diagnostic context not passed down?");
     55 
     56   // If the inline asm had metadata associated with it, pull out a location
     57   // cookie corresponding to which line the error occurred on.
     58   unsigned LocCookie = 0;
     59   if (const MDNode *LocInfo = DiagInfo->LocInfo) {
     60     unsigned ErrorLine = Diag.getLineNo()-1;
     61     if (ErrorLine >= LocInfo->getNumOperands())
     62       ErrorLine = 0;
     63 
     64     if (LocInfo->getNumOperands() != 0)
     65       if (const ConstantInt *CI =
     66           dyn_cast<ConstantInt>(LocInfo->getOperand(ErrorLine)))
     67         LocCookie = CI->getZExtValue();
     68   }
     69 
     70   DiagInfo->DiagHandler(Diag, DiagInfo->DiagContext, LocCookie);
     71 }
     72 
     73 /// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
     74 void AsmPrinter::EmitInlineAsm(StringRef Str, const MDNode *LocMDNode,
     75                                InlineAsm::AsmDialect Dialect) const {
     76   assert(!Str.empty() && "Can't emit empty inline asm block");
     77 
     78   // Remember if the buffer is nul terminated or not so we can avoid a copy.
     79   bool isNullTerminated = Str.back() == 0;
     80   if (isNullTerminated)
     81     Str = Str.substr(0, Str.size()-1);
     82 
     83   // If the output streamer does not have mature MC support or the integrated
     84   // assembler has been disabled, just emit the blob textually.
     85   // Otherwise parse the asm and emit it via MC support.
     86   // This is useful in case the asm parser doesn't handle something but the
     87   // system assembler does.
     88   const MCAsmInfo *MCAI = TM.getMCAsmInfo();
     89   assert(MCAI && "No MCAsmInfo");
     90   if (!MCAI->useIntegratedAssembler() &&
     91       !OutStreamer.isIntegratedAssemblerRequired()) {
     92     OutStreamer.EmitRawText(Str);
     93     emitInlineAsmEnd(TM.getSubtarget<MCSubtargetInfo>(), nullptr);
     94     return;
     95   }
     96 
     97   SourceMgr SrcMgr;
     98   SrcMgrDiagInfo DiagInfo;
     99 
    100   // If the current LLVMContext has an inline asm handler, set it in SourceMgr.
    101   LLVMContext &LLVMCtx = MMI->getModule()->getContext();
    102   bool HasDiagHandler = false;
    103   if (LLVMCtx.getInlineAsmDiagnosticHandler() != nullptr) {
    104     // If the source manager has an issue, we arrange for srcMgrDiagHandler
    105     // to be invoked, getting DiagInfo passed into it.
    106     DiagInfo.LocInfo = LocMDNode;
    107     DiagInfo.DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler();
    108     DiagInfo.DiagContext = LLVMCtx.getInlineAsmDiagnosticContext();
    109     SrcMgr.setDiagHandler(srcMgrDiagHandler, &DiagInfo);
    110     HasDiagHandler = true;
    111   }
    112 
    113   MemoryBuffer *Buffer;
    114   if (isNullTerminated)
    115     Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
    116   else
    117     Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
    118 
    119   // Tell SrcMgr about this buffer, it takes ownership of the buffer.
    120   SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
    121 
    122   std::unique_ptr<MCAsmParser> Parser(
    123       createMCAsmParser(SrcMgr, OutContext, OutStreamer, *MAI));
    124 
    125   // Initialize the parser with a fresh subtarget info. It is better to use a
    126   // new STI here because the parser may modify it and we do not want those
    127   // modifications to persist after parsing the inlineasm. The modifications
    128   // made by the parser will be seen by the code emitters because it passes
    129   // the current STI down to the EncodeInstruction() method.
    130   std::unique_ptr<MCSubtargetInfo> STI(TM.getTarget().createMCSubtargetInfo(
    131       TM.getTargetTriple(), TM.getTargetCPU(), TM.getTargetFeatureString()));
    132 
    133   // Preserve a copy of the original STI because the parser may modify it.  For
    134   // example, when switching between arm and thumb mode. If the target needs to
    135   // emit code to return to the original state it can do so in
    136   // emitInlineAsmEnd().
    137   MCSubtargetInfo STIOrig = *STI;
    138 
    139   MCTargetOptions MCOptions;
    140   if (MF)
    141     MCOptions = MF->getTarget().Options.MCOptions;
    142   std::unique_ptr<MCTargetAsmParser> TAP(
    143       TM.getTarget().createMCAsmParser(*STI, *Parser, *MII, MCOptions));
    144   if (!TAP)
    145     report_fatal_error("Inline asm not supported by this streamer because"
    146                        " we don't have an asm parser for this target\n");
    147   Parser->setAssemblerDialect(Dialect);
    148   Parser->setTargetParser(*TAP.get());
    149 
    150   // Don't implicitly switch to the text section before the asm.
    151   int Res = Parser->Run(/*NoInitialTextSection*/ true,
    152                         /*NoFinalize*/ true);
    153   emitInlineAsmEnd(STIOrig, STI.get());
    154   if (Res && !HasDiagHandler)
    155     report_fatal_error("Error parsing inline asm\n");
    156 }
    157 
    158 static void EmitMSInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
    159                                MachineModuleInfo *MMI, int InlineAsmVariant,
    160                                AsmPrinter *AP, unsigned LocCookie,
    161                                raw_ostream &OS) {
    162   // Switch to the inline assembly variant.
    163   OS << "\t.intel_syntax\n\t";
    164 
    165   const char *LastEmitted = AsmStr; // One past the last character emitted.
    166   unsigned NumOperands = MI->getNumOperands();
    167 
    168   while (*LastEmitted) {
    169     switch (*LastEmitted) {
    170     default: {
    171       // Not a special case, emit the string section literally.
    172       const char *LiteralEnd = LastEmitted+1;
    173       while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
    174              *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
    175         ++LiteralEnd;
    176 
    177       OS.write(LastEmitted, LiteralEnd-LastEmitted);
    178       LastEmitted = LiteralEnd;
    179       break;
    180     }
    181     case '\n':
    182       ++LastEmitted;   // Consume newline character.
    183       OS << '\n';      // Indent code with newline.
    184       break;
    185     case '$': {
    186       ++LastEmitted;   // Consume '$' character.
    187       bool Done = true;
    188 
    189       // Handle escapes.
    190       switch (*LastEmitted) {
    191       default: Done = false; break;
    192       case '$':
    193         ++LastEmitted;  // Consume second '$' character.
    194         break;
    195       }
    196       if (Done) break;
    197 
    198       const char *IDStart = LastEmitted;
    199       const char *IDEnd = IDStart;
    200       while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
    201 
    202       unsigned Val;
    203       if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
    204         report_fatal_error("Bad $ operand number in inline asm string: '" +
    205                            Twine(AsmStr) + "'");
    206       LastEmitted = IDEnd;
    207 
    208       if (Val >= NumOperands-1)
    209         report_fatal_error("Invalid $ operand number in inline asm string: '" +
    210                            Twine(AsmStr) + "'");
    211 
    212       // Okay, we finally have a value number.  Ask the target to print this
    213       // operand!
    214       unsigned OpNo = InlineAsm::MIOp_FirstOperand;
    215 
    216       bool Error = false;
    217 
    218       // Scan to find the machine operand number for the operand.
    219       for (; Val; --Val) {
    220         if (OpNo >= MI->getNumOperands()) break;
    221         unsigned OpFlags = MI->getOperand(OpNo).getImm();
    222         OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
    223       }
    224 
    225       // We may have a location metadata attached to the end of the
    226       // instruction, and at no point should see metadata at any
    227       // other point while processing. It's an error if so.
    228       if (OpNo >= MI->getNumOperands() ||
    229           MI->getOperand(OpNo).isMetadata()) {
    230         Error = true;
    231       } else {
    232         unsigned OpFlags = MI->getOperand(OpNo).getImm();
    233         ++OpNo;  // Skip over the ID number.
    234 
    235         if (InlineAsm::isMemKind(OpFlags)) {
    236           Error = AP->PrintAsmMemoryOperand(MI, OpNo, InlineAsmVariant,
    237                                             /*Modifier*/ nullptr, OS);
    238         } else {
    239           Error = AP->PrintAsmOperand(MI, OpNo, InlineAsmVariant,
    240                                       /*Modifier*/ nullptr, OS);
    241         }
    242       }
    243       if (Error) {
    244         std::string msg;
    245         raw_string_ostream Msg(msg);
    246         Msg << "invalid operand in inline asm: '" << AsmStr << "'";
    247         MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
    248       }
    249       break;
    250     }
    251     }
    252   }
    253   OS << "\n\t.att_syntax\n" << (char)0;  // null terminate string.
    254 }
    255 
    256 static void EmitGCCInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
    257                                 MachineModuleInfo *MMI, int InlineAsmVariant,
    258                                 int AsmPrinterVariant, AsmPrinter *AP,
    259                                 unsigned LocCookie, raw_ostream &OS) {
    260   int CurVariant = -1;            // The number of the {.|.|.} region we are in.
    261   const char *LastEmitted = AsmStr; // One past the last character emitted.
    262   unsigned NumOperands = MI->getNumOperands();
    263 
    264   OS << '\t';
    265 
    266   while (*LastEmitted) {
    267     switch (*LastEmitted) {
    268     default: {
    269       // Not a special case, emit the string section literally.
    270       const char *LiteralEnd = LastEmitted+1;
    271       while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
    272              *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
    273         ++LiteralEnd;
    274       if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    275         OS.write(LastEmitted, LiteralEnd-LastEmitted);
    276       LastEmitted = LiteralEnd;
    277       break;
    278     }
    279     case '\n':
    280       ++LastEmitted;   // Consume newline character.
    281       OS << '\n';      // Indent code with newline.
    282       break;
    283     case '$': {
    284       ++LastEmitted;   // Consume '$' character.
    285       bool Done = true;
    286 
    287       // Handle escapes.
    288       switch (*LastEmitted) {
    289       default: Done = false; break;
    290       case '$':     // $$ -> $
    291         if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    292           OS << '$';
    293         ++LastEmitted;  // Consume second '$' character.
    294         break;
    295       case '(':             // $( -> same as GCC's { character.
    296         ++LastEmitted;      // Consume '(' character.
    297         if (CurVariant != -1)
    298           report_fatal_error("Nested variants found in inline asm string: '" +
    299                              Twine(AsmStr) + "'");
    300         CurVariant = 0;     // We're in the first variant now.
    301         break;
    302       case '|':
    303         ++LastEmitted;  // consume '|' character.
    304         if (CurVariant == -1)
    305           OS << '|';       // this is gcc's behavior for | outside a variant
    306         else
    307           ++CurVariant;   // We're in the next variant.
    308         break;
    309       case ')':         // $) -> same as GCC's } char.
    310         ++LastEmitted;  // consume ')' character.
    311         if (CurVariant == -1)
    312           OS << '}';     // this is gcc's behavior for } outside a variant
    313         else
    314           CurVariant = -1;
    315         break;
    316       }
    317       if (Done) break;
    318 
    319       bool HasCurlyBraces = false;
    320       if (*LastEmitted == '{') {     // ${variable}
    321         ++LastEmitted;               // Consume '{' character.
    322         HasCurlyBraces = true;
    323       }
    324 
    325       // If we have ${:foo}, then this is not a real operand reference, it is a
    326       // "magic" string reference, just like in .td files.  Arrange to call
    327       // PrintSpecial.
    328       if (HasCurlyBraces && *LastEmitted == ':') {
    329         ++LastEmitted;
    330         const char *StrStart = LastEmitted;
    331         const char *StrEnd = strchr(StrStart, '}');
    332         if (!StrEnd)
    333           report_fatal_error("Unterminated ${:foo} operand in inline asm"
    334                              " string: '" + Twine(AsmStr) + "'");
    335 
    336         std::string Val(StrStart, StrEnd);
    337         AP->PrintSpecial(MI, OS, Val.c_str());
    338         LastEmitted = StrEnd+1;
    339         break;
    340       }
    341 
    342       const char *IDStart = LastEmitted;
    343       const char *IDEnd = IDStart;
    344       while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
    345 
    346       unsigned Val;
    347       if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
    348         report_fatal_error("Bad $ operand number in inline asm string: '" +
    349                            Twine(AsmStr) + "'");
    350       LastEmitted = IDEnd;
    351 
    352       char Modifier[2] = { 0, 0 };
    353 
    354       if (HasCurlyBraces) {
    355         // If we have curly braces, check for a modifier character.  This
    356         // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
    357         if (*LastEmitted == ':') {
    358           ++LastEmitted;    // Consume ':' character.
    359           if (*LastEmitted == 0)
    360             report_fatal_error("Bad ${:} expression in inline asm string: '" +
    361                                Twine(AsmStr) + "'");
    362 
    363           Modifier[0] = *LastEmitted;
    364           ++LastEmitted;    // Consume modifier character.
    365         }
    366 
    367         if (*LastEmitted != '}')
    368           report_fatal_error("Bad ${} expression in inline asm string: '" +
    369                              Twine(AsmStr) + "'");
    370         ++LastEmitted;    // Consume '}' character.
    371       }
    372 
    373       if (Val >= NumOperands-1)
    374         report_fatal_error("Invalid $ operand number in inline asm string: '" +
    375                            Twine(AsmStr) + "'");
    376 
    377       // Okay, we finally have a value number.  Ask the target to print this
    378       // operand!
    379       if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
    380         unsigned OpNo = InlineAsm::MIOp_FirstOperand;
    381 
    382         bool Error = false;
    383 
    384         // Scan to find the machine operand number for the operand.
    385         for (; Val; --Val) {
    386           if (OpNo >= MI->getNumOperands()) break;
    387           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    388           OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
    389         }
    390 
    391         // We may have a location metadata attached to the end of the
    392         // instruction, and at no point should see metadata at any
    393         // other point while processing. It's an error if so.
    394         if (OpNo >= MI->getNumOperands() ||
    395             MI->getOperand(OpNo).isMetadata()) {
    396           Error = true;
    397         } else {
    398           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    399           ++OpNo;  // Skip over the ID number.
    400 
    401           if (Modifier[0] == 'l')  // labels are target independent
    402             // FIXME: What if the operand isn't an MBB, report error?
    403             OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
    404           else {
    405             if (InlineAsm::isMemKind(OpFlags)) {
    406               Error = AP->PrintAsmMemoryOperand(MI, OpNo, InlineAsmVariant,
    407                                                 Modifier[0] ? Modifier : nullptr,
    408                                                 OS);
    409             } else {
    410               Error = AP->PrintAsmOperand(MI, OpNo, InlineAsmVariant,
    411                                           Modifier[0] ? Modifier : nullptr, OS);
    412             }
    413           }
    414         }
    415         if (Error) {
    416           std::string msg;
    417           raw_string_ostream Msg(msg);
    418           Msg << "invalid operand in inline asm: '" << AsmStr << "'";
    419           MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
    420         }
    421       }
    422       break;
    423     }
    424     }
    425   }
    426   OS << '\n' << (char)0;  // null terminate string.
    427 }
    428 
    429 /// EmitInlineAsm - This method formats and emits the specified machine
    430 /// instruction that is an inline asm.
    431 void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
    432   assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
    433 
    434   // Count the number of register definitions to find the asm string.
    435   unsigned NumDefs = 0;
    436   for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
    437        ++NumDefs)
    438     assert(NumDefs != MI->getNumOperands()-2 && "No asm string?");
    439 
    440   assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
    441 
    442   // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
    443   const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
    444 
    445   // If this asmstr is empty, just print the #APP/#NOAPP markers.
    446   // These are useful to see where empty asm's wound up.
    447   if (AsmStr[0] == 0) {
    448     OutStreamer.emitRawComment(MAI->getInlineAsmStart());
    449     OutStreamer.emitRawComment(MAI->getInlineAsmEnd());
    450     return;
    451   }
    452 
    453   // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
    454   // enabled, so we use emitRawComment.
    455   OutStreamer.emitRawComment(MAI->getInlineAsmStart());
    456 
    457   // Get the !srcloc metadata node if we have it, and decode the loc cookie from
    458   // it.
    459   unsigned LocCookie = 0;
    460   const MDNode *LocMD = nullptr;
    461   for (unsigned i = MI->getNumOperands(); i != 0; --i) {
    462     if (MI->getOperand(i-1).isMetadata() &&
    463         (LocMD = MI->getOperand(i-1).getMetadata()) &&
    464         LocMD->getNumOperands() != 0) {
    465       if (const ConstantInt *CI = dyn_cast<ConstantInt>(LocMD->getOperand(0))) {
    466         LocCookie = CI->getZExtValue();
    467         break;
    468       }
    469     }
    470   }
    471 
    472   // Emit the inline asm to a temporary string so we can emit it through
    473   // EmitInlineAsm.
    474   SmallString<256> StringData;
    475   raw_svector_ostream OS(StringData);
    476 
    477   // The variant of the current asmprinter.
    478   int AsmPrinterVariant = MAI->getAssemblerDialect();
    479   InlineAsm::AsmDialect InlineAsmVariant = MI->getInlineAsmDialect();
    480   AsmPrinter *AP = const_cast<AsmPrinter*>(this);
    481   if (InlineAsmVariant == InlineAsm::AD_ATT)
    482     EmitGCCInlineAsmStr(AsmStr, MI, MMI, InlineAsmVariant, AsmPrinterVariant,
    483                         AP, LocCookie, OS);
    484   else
    485     EmitMSInlineAsmStr(AsmStr, MI, MMI, InlineAsmVariant, AP, LocCookie, OS);
    486 
    487   EmitInlineAsm(OS.str(), LocMD, MI->getInlineAsmDialect());
    488 
    489   // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
    490   // enabled, so we use emitRawComment.
    491   OutStreamer.emitRawComment(MAI->getInlineAsmEnd());
    492 }
    493 
    494 
    495 /// PrintSpecial - Print information related to the specified machine instr
    496 /// that is independent of the operand, and may be independent of the instr
    497 /// itself.  This can be useful for portably encoding the comment character
    498 /// or other bits of target-specific knowledge into the asmstrings.  The
    499 /// syntax used is ${:comment}.  Targets can override this to add support
    500 /// for their own strange codes.
    501 void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
    502                               const char *Code) const {
    503   const DataLayout *DL = TM.getDataLayout();
    504   if (!strcmp(Code, "private")) {
    505     OS << DL->getPrivateGlobalPrefix();
    506   } else if (!strcmp(Code, "comment")) {
    507     OS << MAI->getCommentString();
    508   } else if (!strcmp(Code, "uid")) {
    509     // Comparing the address of MI isn't sufficient, because machineinstrs may
    510     // be allocated to the same address across functions.
    511 
    512     // If this is a new LastFn instruction, bump the counter.
    513     if (LastMI != MI || LastFn != getFunctionNumber()) {
    514       ++Counter;
    515       LastMI = MI;
    516       LastFn = getFunctionNumber();
    517     }
    518     OS << Counter;
    519   } else {
    520     std::string msg;
    521     raw_string_ostream Msg(msg);
    522     Msg << "Unknown special formatter '" << Code
    523          << "' for machine instr: " << *MI;
    524     report_fatal_error(Msg.str());
    525   }
    526 }
    527 
    528 /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
    529 /// instruction, using the specified assembler variant.  Targets should
    530 /// override this to format as appropriate.
    531 bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
    532                                  unsigned AsmVariant, const char *ExtraCode,
    533                                  raw_ostream &O) {
    534   // Does this asm operand have a single letter operand modifier?
    535   if (ExtraCode && ExtraCode[0]) {
    536     if (ExtraCode[1] != 0) return true; // Unknown modifier.
    537 
    538     const MachineOperand &MO = MI->getOperand(OpNo);
    539     switch (ExtraCode[0]) {
    540     default:
    541       return true;  // Unknown modifier.
    542     case 'c': // Substitute immediate value without immediate syntax
    543       if (MO.getType() != MachineOperand::MO_Immediate)
    544         return true;
    545       O << MO.getImm();
    546       return false;
    547     case 'n':  // Negate the immediate constant.
    548       if (MO.getType() != MachineOperand::MO_Immediate)
    549         return true;
    550       O << -MO.getImm();
    551       return false;
    552     }
    553   }
    554   return true;
    555 }
    556 
    557 bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
    558                                        unsigned AsmVariant,
    559                                        const char *ExtraCode, raw_ostream &O) {
    560   // Target doesn't support this yet!
    561   return true;
    562 }
    563 
    564 void AsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
    565                                   const MCSubtargetInfo *EndInfo) const {}
    566