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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 #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/MCTargetAsmParser.h"
     27 #include "llvm/Target/TargetMachine.h"
     28 #include "llvm/ADT/OwningPtr.h"
     29 #include "llvm/ADT/SmallString.h"
     30 #include "llvm/ADT/Twine.h"
     31 #include "llvm/Support/ErrorHandling.h"
     32 #include "llvm/Support/MemoryBuffer.h"
     33 #include "llvm/Support/SourceMgr.h"
     34 #include "llvm/Support/TargetRegistry.h"
     35 #include "llvm/Support/raw_ostream.h"
     36 using namespace llvm;
     37 
     38 namespace {
     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.
     49 static 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.
     71 void 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(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<MCTargetAsmParser>
    125     TAP(TM.getTarget().createMCAsmParser(*STI, *Parser));
    126   if (!TAP)
    127     report_fatal_error("Inline asm not supported by this streamer because"
    128                        " we don't have an asm parser for this target\n");
    129   Parser->setTargetParser(*TAP.get());
    130 
    131   // Don't implicitly switch to the text section before the asm.
    132   int Res = Parser->Run(/*NoInitialTextSection*/ true,
    133                         /*NoFinalize*/ true);
    134   if (Res && !HasDiagHandler)
    135     report_fatal_error("Error parsing inline asm\n");
    136 }
    137 
    138 
    139 /// EmitInlineAsm - This method formats and emits the specified machine
    140 /// instruction that is an inline asm.
    141 void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
    142   assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
    143 
    144   unsigned NumOperands = MI->getNumOperands();
    145 
    146   // Count the number of register definitions to find the asm string.
    147   unsigned NumDefs = 0;
    148   for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
    149        ++NumDefs)
    150     assert(NumDefs != NumOperands-2 && "No asm string?");
    151 
    152   assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
    153 
    154   // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
    155   const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
    156 
    157   // If this asmstr is empty, just print the #APP/#NOAPP markers.
    158   // These are useful to see where empty asm's wound up.
    159   if (AsmStr[0] == 0) {
    160     // Don't emit the comments if writing to a .o file.
    161     if (!OutStreamer.hasRawTextSupport()) return;
    162 
    163     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    164                             MAI->getInlineAsmStart());
    165     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    166                             MAI->getInlineAsmEnd());
    167     return;
    168   }
    169 
    170   // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
    171   // enabled, so we use EmitRawText.
    172   if (OutStreamer.hasRawTextSupport())
    173     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    174                             MAI->getInlineAsmStart());
    175 
    176   // Get the !srcloc metadata node if we have it, and decode the loc cookie from
    177   // it.
    178   unsigned LocCookie = 0;
    179   const MDNode *LocMD = 0;
    180   for (unsigned i = MI->getNumOperands(); i != 0; --i) {
    181     if (MI->getOperand(i-1).isMetadata() &&
    182         (LocMD = MI->getOperand(i-1).getMetadata()) &&
    183         LocMD->getNumOperands() != 0) {
    184       if (const ConstantInt *CI = dyn_cast<ConstantInt>(LocMD->getOperand(0))) {
    185         LocCookie = CI->getZExtValue();
    186         break;
    187       }
    188     }
    189   }
    190 
    191   // Emit the inline asm to a temporary string so we can emit it through
    192   // EmitInlineAsm.
    193   SmallString<256> StringData;
    194   raw_svector_ostream OS(StringData);
    195 
    196   OS << '\t';
    197 
    198   // The variant of the current asmprinter.
    199   int AsmPrinterVariant = MAI->getAssemblerDialect();
    200 
    201   int CurVariant = -1;            // The number of the {.|.|.} region we are in.
    202   const char *LastEmitted = AsmStr; // One past the last character emitted.
    203 
    204   while (*LastEmitted) {
    205     switch (*LastEmitted) {
    206     default: {
    207       // Not a special case, emit the string section literally.
    208       const char *LiteralEnd = LastEmitted+1;
    209       while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
    210              *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
    211         ++LiteralEnd;
    212       if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    213         OS.write(LastEmitted, LiteralEnd-LastEmitted);
    214       LastEmitted = LiteralEnd;
    215       break;
    216     }
    217     case '\n':
    218       ++LastEmitted;   // Consume newline character.
    219       OS << '\n';      // Indent code with newline.
    220       break;
    221     case '$': {
    222       ++LastEmitted;   // Consume '$' character.
    223       bool Done = true;
    224 
    225       // Handle escapes.
    226       switch (*LastEmitted) {
    227       default: Done = false; break;
    228       case '$':     // $$ -> $
    229         if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    230           OS << '$';
    231         ++LastEmitted;  // Consume second '$' character.
    232         break;
    233       case '(':             // $( -> same as GCC's { character.
    234         ++LastEmitted;      // Consume '(' character.
    235         if (CurVariant != -1)
    236           report_fatal_error("Nested variants found in inline asm string: '" +
    237                              Twine(AsmStr) + "'");
    238         CurVariant = 0;     // We're in the first variant now.
    239         break;
    240       case '|':
    241         ++LastEmitted;  // consume '|' character.
    242         if (CurVariant == -1)
    243           OS << '|';       // this is gcc's behavior for | outside a variant
    244         else
    245           ++CurVariant;   // We're in the next variant.
    246         break;
    247       case ')':         // $) -> same as GCC's } char.
    248         ++LastEmitted;  // consume ')' character.
    249         if (CurVariant == -1)
    250           OS << '}';     // this is gcc's behavior for } outside a variant
    251         else
    252           CurVariant = -1;
    253         break;
    254       }
    255       if (Done) break;
    256 
    257       bool HasCurlyBraces = false;
    258       if (*LastEmitted == '{') {     // ${variable}
    259         ++LastEmitted;               // Consume '{' character.
    260         HasCurlyBraces = true;
    261       }
    262 
    263       // If we have ${:foo}, then this is not a real operand reference, it is a
    264       // "magic" string reference, just like in .td files.  Arrange to call
    265       // PrintSpecial.
    266       if (HasCurlyBraces && *LastEmitted == ':') {
    267         ++LastEmitted;
    268         const char *StrStart = LastEmitted;
    269         const char *StrEnd = strchr(StrStart, '}');
    270         if (StrEnd == 0)
    271           report_fatal_error("Unterminated ${:foo} operand in inline asm"
    272                              " string: '" + Twine(AsmStr) + "'");
    273 
    274         std::string Val(StrStart, StrEnd);
    275         PrintSpecial(MI, OS, Val.c_str());
    276         LastEmitted = StrEnd+1;
    277         break;
    278       }
    279 
    280       const char *IDStart = LastEmitted;
    281       const char *IDEnd = IDStart;
    282       while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
    283 
    284       unsigned Val;
    285       if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
    286         report_fatal_error("Bad $ operand number in inline asm string: '" +
    287                            Twine(AsmStr) + "'");
    288       LastEmitted = IDEnd;
    289 
    290       char Modifier[2] = { 0, 0 };
    291 
    292       if (HasCurlyBraces) {
    293         // If we have curly braces, check for a modifier character.  This
    294         // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
    295         if (*LastEmitted == ':') {
    296           ++LastEmitted;    // Consume ':' character.
    297           if (*LastEmitted == 0)
    298             report_fatal_error("Bad ${:} expression in inline asm string: '" +
    299                                Twine(AsmStr) + "'");
    300 
    301           Modifier[0] = *LastEmitted;
    302           ++LastEmitted;    // Consume modifier character.
    303         }
    304 
    305         if (*LastEmitted != '}')
    306           report_fatal_error("Bad ${} expression in inline asm string: '" +
    307                              Twine(AsmStr) + "'");
    308         ++LastEmitted;    // Consume '}' character.
    309       }
    310 
    311       if (Val >= NumOperands-1)
    312         report_fatal_error("Invalid $ operand number in inline asm string: '" +
    313                            Twine(AsmStr) + "'");
    314 
    315       // Okay, we finally have a value number.  Ask the target to print this
    316       // operand!
    317       if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
    318         unsigned OpNo = InlineAsm::MIOp_FirstOperand;
    319 
    320         bool Error = false;
    321 
    322         // Scan to find the machine operand number for the operand.
    323         for (; Val; --Val) {
    324           if (OpNo >= MI->getNumOperands()) break;
    325           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    326           OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
    327         }
    328 
    329         if (OpNo >= MI->getNumOperands()) {
    330           Error = true;
    331         } else {
    332           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    333           ++OpNo;  // Skip over the ID number.
    334 
    335           if (Modifier[0] == 'l')  // labels are target independent
    336             // FIXME: What if the operand isn't an MBB, report error?
    337             OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
    338           else {
    339             AsmPrinter *AP = const_cast<AsmPrinter*>(this);
    340             if (InlineAsm::isMemKind(OpFlags)) {
    341               Error = AP->PrintAsmMemoryOperand(MI, OpNo, AsmPrinterVariant,
    342                                                 Modifier[0] ? Modifier : 0,
    343                                                 OS);
    344             } else {
    345               Error = AP->PrintAsmOperand(MI, OpNo, AsmPrinterVariant,
    346                                           Modifier[0] ? Modifier : 0, OS);
    347             }
    348           }
    349         }
    350         if (Error) {
    351           std::string msg;
    352           raw_string_ostream Msg(msg);
    353           Msg << "invalid operand in inline asm: '" << AsmStr << "'";
    354           MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
    355         }
    356       }
    357       break;
    358     }
    359     }
    360   }
    361   OS << '\n' << (char)0;  // null terminate string.
    362   EmitInlineAsm(OS.str(), LocMD);
    363 
    364   // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
    365   // enabled, so we use EmitRawText.
    366   if (OutStreamer.hasRawTextSupport())
    367     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    368                             MAI->getInlineAsmEnd());
    369 }
    370 
    371 
    372 /// PrintSpecial - Print information related to the specified machine instr
    373 /// that is independent of the operand, and may be independent of the instr
    374 /// itself.  This can be useful for portably encoding the comment character
    375 /// or other bits of target-specific knowledge into the asmstrings.  The
    376 /// syntax used is ${:comment}.  Targets can override this to add support
    377 /// for their own strange codes.
    378 void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
    379                               const char *Code) const {
    380   if (!strcmp(Code, "private")) {
    381     OS << MAI->getPrivateGlobalPrefix();
    382   } else if (!strcmp(Code, "comment")) {
    383     OS << MAI->getCommentString();
    384   } else if (!strcmp(Code, "uid")) {
    385     // Comparing the address of MI isn't sufficient, because machineinstrs may
    386     // be allocated to the same address across functions.
    387 
    388     // If this is a new LastFn instruction, bump the counter.
    389     if (LastMI != MI || LastFn != getFunctionNumber()) {
    390       ++Counter;
    391       LastMI = MI;
    392       LastFn = getFunctionNumber();
    393     }
    394     OS << Counter;
    395   } else {
    396     std::string msg;
    397     raw_string_ostream Msg(msg);
    398     Msg << "Unknown special formatter '" << Code
    399          << "' for machine instr: " << *MI;
    400     report_fatal_error(Msg.str());
    401   }
    402 }
    403 
    404 /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
    405 /// instruction, using the specified assembler variant.  Targets should
    406 /// override this to format as appropriate.
    407 bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
    408                                  unsigned AsmVariant, const char *ExtraCode,
    409                                  raw_ostream &O) {
    410   // Target doesn't support this yet!
    411   return true;
    412 }
    413 
    414 bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
    415                                        unsigned AsmVariant,
    416                                        const char *ExtraCode, raw_ostream &O) {
    417   // Target doesn't support this yet!
    418   return true;
    419 }
    420 
    421