Home | History | Annotate | Download | only in AsmPrinter 
      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/Target/TargetAsmParser.h"
     27 #include "llvm/Target/TargetMachine.h"
     28 #include "llvm/Target/TargetRegistry.h"
     29 #include "llvm/ADT/OwningPtr.h"
     30 #include "llvm/ADT/SmallString.h"
     31 #include "llvm/ADT/Twine.h"
     32 #include "llvm/Support/ErrorHandling.h"
     33 #include "llvm/Support/MemoryBuffer.h"
     34 #include "llvm/Support/SourceMgr.h"
     35 #include "llvm/Support/raw_ostream.h"
     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 #ifndef ANDROID_TARGET_BUILD
     73   assert(!Str.empty() && "Can't emit empty inline asm block");
     74 
     75   // Remember if the buffer is nul terminated or not so we can avoid a copy.
     76   bool isNullTerminated = Str.back() == 0;
     77   if (isNullTerminated)
     78     Str = Str.substr(0, Str.size()-1);
     79 
     80   // If the output streamer is actually a .s file, just emit the blob textually.
     81   // This is useful in case the asm parser doesn't handle something but the
     82   // system assembler does.
     83   if (OutStreamer.hasRawTextSupport()) {
     84     OutStreamer.EmitRawText(Str);
     85     return;
     86   }
     87 
     88   SourceMgr SrcMgr;
     89   SrcMgrDiagInfo DiagInfo;
     90 
     91   // If the current LLVMContext has an inline asm handler, set it in SourceMgr.
     92   LLVMContext &LLVMCtx = MMI->getModule()->getContext();
     93   bool HasDiagHandler = false;
     94   if (LLVMCtx.getInlineAsmDiagnosticHandler() != 0) {
     95     // If the source manager has an issue, we arrange for SrcMgrDiagHandler
     96     // to be invoked, getting DiagInfo passed into it.
     97     DiagInfo.LocInfo = LocMDNode;
     98     DiagInfo.DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler();
     99     DiagInfo.DiagContext = LLVMCtx.getInlineAsmDiagnosticContext();
    100     SrcMgr.setDiagHandler(SrcMgrDiagHandler, &DiagInfo);
    101     HasDiagHandler = true;
    102   }
    103 
    104   MemoryBuffer *Buffer;
    105   if (isNullTerminated)
    106     Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
    107   else
    108     Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
    109 
    110   // Tell SrcMgr about this buffer, it takes ownership of the buffer.
    111   SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
    112 
    113   OwningPtr<MCAsmParser> Parser(createMCAsmParser(TM.getTarget(), SrcMgr,
    114                                                   OutContext, OutStreamer,
    115                                                   *MAI));
    116 
    117   // FIXME: It would be nice if we can avoid createing a new instance of
    118   // MCSubtargetInfo here given TargetSubtargetInfo is available. However,
    119   // we have to watch out for asm directives which can change subtarget
    120   // state. e.g. .code 16, .code 32.
    121   OwningPtr<MCSubtargetInfo>
    122     STI(TM.getTarget().createMCSubtargetInfo(TM.getTargetTriple(),
    123                                              TM.getTargetCPU(),
    124                                              TM.getTargetFeatureString()));
    125   OwningPtr<TargetAsmParser> TAP(TM.getTarget().createAsmParser(*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 #endif // ANDROID_TARGET_BUILD
    137 }
    138 
    139 
    140 /// EmitInlineAsm - This method formats and emits the specified machine
    141 /// instruction that is an inline asm.
    142 void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
    143 #ifndef ANDROID_TARGET_BUILD
    144   assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
    145 
    146   unsigned NumOperands = MI->getNumOperands();
    147 
    148   // Count the number of register definitions to find the asm string.
    149   unsigned NumDefs = 0;
    150   for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
    151        ++NumDefs)
    152     assert(NumDefs != NumOperands-2 && "No asm string?");
    153 
    154   assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
    155 
    156   // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
    157   const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
    158 
    159   // If this asmstr is empty, just print the #APP/#NOAPP markers.
    160   // These are useful to see where empty asm's wound up.
    161   if (AsmStr[0] == 0) {
    162     // Don't emit the comments if writing to a .o file.
    163     if (!OutStreamer.hasRawTextSupport()) return;
    164 
    165     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    166                             MAI->getInlineAsmStart());
    167     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    168                             MAI->getInlineAsmEnd());
    169     return;
    170   }
    171 
    172   // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
    173   // enabled, so we use EmitRawText.
    174   if (OutStreamer.hasRawTextSupport())
    175     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    176                             MAI->getInlineAsmStart());
    177 
    178   // Get the !srcloc metadata node if we have it, and decode the loc cookie from
    179   // it.
    180   unsigned LocCookie = 0;
    181   const MDNode *LocMD = 0;
    182   for (unsigned i = MI->getNumOperands(); i != 0; --i) {
    183     if (MI->getOperand(i-1).isMetadata() &&
    184         (LocMD = MI->getOperand(i-1).getMetadata()) &&
    185         LocMD->getNumOperands() != 0) {
    186       if (const ConstantInt *CI = dyn_cast<ConstantInt>(LocMD->getOperand(0))) {
    187         LocCookie = CI->getZExtValue();
    188         break;
    189       }
    190     }
    191   }
    192 
    193   // Emit the inline asm to a temporary string so we can emit it through
    194   // EmitInlineAsm.
    195   SmallString<256> StringData;
    196   raw_svector_ostream OS(StringData);
    197 
    198   OS << '\t';
    199 
    200   // The variant of the current asmprinter.
    201   int AsmPrinterVariant = MAI->getAssemblerDialect();
    202 
    203   int CurVariant = -1;            // The number of the {.|.|.} region we are in.
    204   const char *LastEmitted = AsmStr; // One past the last character emitted.
    205 
    206   while (*LastEmitted) {
    207     switch (*LastEmitted) {
    208     default: {
    209       // Not a special case, emit the string section literally.
    210       const char *LiteralEnd = LastEmitted+1;
    211       while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
    212              *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
    213         ++LiteralEnd;
    214       if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    215         OS.write(LastEmitted, LiteralEnd-LastEmitted);
    216       LastEmitted = LiteralEnd;
    217       break;
    218     }
    219     case '\n':
    220       ++LastEmitted;   // Consume newline character.
    221       OS << '\n';      // Indent code with newline.
    222       break;
    223     case '$': {
    224       ++LastEmitted;   // Consume '$' character.
    225       bool Done = true;
    226 
    227       // Handle escapes.
    228       switch (*LastEmitted) {
    229       default: Done = false; break;
    230       case '$':     // $$ -> $
    231         if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    232           OS << '$';
    233         ++LastEmitted;  // Consume second '$' character.
    234         break;
    235       case '(':             // $( -> same as GCC's { character.
    236         ++LastEmitted;      // Consume '(' character.
    237         if (CurVariant != -1)
    238           report_fatal_error("Nested variants found in inline asm string: '" +
    239                              Twine(AsmStr) + "'");
    240         CurVariant = 0;     // We're in the first variant now.
    241         break;
    242       case '|':
    243         ++LastEmitted;  // consume '|' character.
    244         if (CurVariant == -1)
    245           OS << '|';       // this is gcc's behavior for | outside a variant
    246         else
    247           ++CurVariant;   // We're in the next variant.
    248         break;
    249       case ')':         // $) -> same as GCC's } char.
    250         ++LastEmitted;  // consume ')' character.
    251         if (CurVariant == -1)
    252           OS << '}';     // this is gcc's behavior for } outside a variant
    253         else
    254           CurVariant = -1;
    255         break;
    256       }
    257       if (Done) break;
    258 
    259       bool HasCurlyBraces = false;
    260       if (*LastEmitted == '{') {     // ${variable}
    261         ++LastEmitted;               // Consume '{' character.
    262         HasCurlyBraces = true;
    263       }
    264 
    265       // If we have ${:foo}, then this is not a real operand reference, it is a
    266       // "magic" string reference, just like in .td files.  Arrange to call
    267       // PrintSpecial.
    268       if (HasCurlyBraces && *LastEmitted == ':') {
    269         ++LastEmitted;
    270         const char *StrStart = LastEmitted;
    271         const char *StrEnd = strchr(StrStart, '}');
    272         if (StrEnd == 0)
    273           report_fatal_error("Unterminated ${:foo} operand in inline asm"
    274                              " string: '" + Twine(AsmStr) + "'");
    275 
    276         std::string Val(StrStart, StrEnd);
    277         PrintSpecial(MI, OS, Val.c_str());
    278         LastEmitted = StrEnd+1;
    279         break;
    280       }
    281 
    282       const char *IDStart = LastEmitted;
    283       const char *IDEnd = IDStart;
    284       while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
    285 
    286       unsigned Val;
    287       if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
    288         report_fatal_error("Bad $ operand number in inline asm string: '" +
    289                            Twine(AsmStr) + "'");
    290       LastEmitted = IDEnd;
    291 
    292       char Modifier[2] = { 0, 0 };
    293 
    294       if (HasCurlyBraces) {
    295         // If we have curly braces, check for a modifier character.  This
    296         // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
    297         if (*LastEmitted == ':') {
    298           ++LastEmitted;    // Consume ':' character.
    299           if (*LastEmitted == 0)
    300             report_fatal_error("Bad ${:} expression in inline asm string: '" +
    301                                Twine(AsmStr) + "'");
    302 
    303           Modifier[0] = *LastEmitted;
    304           ++LastEmitted;    // Consume modifier character.
    305         }
    306 
    307         if (*LastEmitted != '}')
    308           report_fatal_error("Bad ${} expression in inline asm string: '" +
    309                              Twine(AsmStr) + "'");
    310         ++LastEmitted;    // Consume '}' character.
    311       }
    312 
    313       if (Val >= NumOperands-1)
    314         report_fatal_error("Invalid $ operand number in inline asm string: '" +
    315                            Twine(AsmStr) + "'");
    316 
    317       // Okay, we finally have a value number.  Ask the target to print this
    318       // operand!
    319       if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
    320         unsigned OpNo = InlineAsm::MIOp_FirstOperand;
    321 
    322         bool Error = false;
    323 
    324         // Scan to find the machine operand number for the operand.
    325         for (; Val; --Val) {
    326           if (OpNo >= MI->getNumOperands()) break;
    327           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    328           OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
    329         }
    330 
    331         if (OpNo >= MI->getNumOperands()) {
    332           Error = true;
    333         } else {
    334           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    335           ++OpNo;  // Skip over the ID number.
    336 
    337           if (Modifier[0] == 'l')  // labels are target independent
    338             // FIXME: What if the operand isn't an MBB, report error?
    339             OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
    340           else {
    341             AsmPrinter *AP = const_cast<AsmPrinter*>(this);
    342             if (InlineAsm::isMemKind(OpFlags)) {
    343               Error = AP->PrintAsmMemoryOperand(MI, OpNo, AsmPrinterVariant,
    344                                                 Modifier[0] ? Modifier : 0,
    345                                                 OS);
    346             } else {
    347               Error = AP->PrintAsmOperand(MI, OpNo, AsmPrinterVariant,
    348                                           Modifier[0] ? Modifier : 0, OS);
    349             }
    350           }
    351         }
    352         if (Error) {
    353           std::string msg;
    354           raw_string_ostream Msg(msg);
    355           Msg << "invalid operand in inline asm: '" << AsmStr << "'";
    356           MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
    357         }
    358       }
    359       break;
    360     }
    361     }
    362   }
    363   OS << '\n' << (char)0;  // null terminate string.
    364   EmitInlineAsm(OS.str(), LocMD);
    365 
    366   // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
    367   // enabled, so we use EmitRawText.
    368   if (OutStreamer.hasRawTextSupport())
    369     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    370                             MAI->getInlineAsmEnd());
    371 #endif // ANDROID_TARGET_BUILD
    372 }
    373 
    374 
    375 /// PrintSpecial - Print information related to the specified machine instr
    376 /// that is independent of the operand, and may be independent of the instr
    377 /// itself.  This can be useful for portably encoding the comment character
    378 /// or other bits of target-specific knowledge into the asmstrings.  The
    379 /// syntax used is ${:comment}.  Targets can override this to add support
    380 /// for their own strange codes.
    381 void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
    382                               const char *Code) const {
    383   if (!strcmp(Code, "private")) {
    384     OS << MAI->getPrivateGlobalPrefix();
    385   } else if (!strcmp(Code, "comment")) {
    386     OS << MAI->getCommentString();
    387   } else if (!strcmp(Code, "uid")) {
    388     // Comparing the address of MI isn't sufficient, because machineinstrs may
    389     // be allocated to the same address across functions.
    390 
    391     // If this is a new LastFn instruction, bump the counter.
    392     if (LastMI != MI || LastFn != getFunctionNumber()) {
    393       ++Counter;
    394       LastMI = MI;
    395       LastFn = getFunctionNumber();
    396     }
    397     OS << Counter;
    398   } else {
    399     std::string msg;
    400     raw_string_ostream Msg(msg);
    401     Msg << "Unknown special formatter '" << Code
    402          << "' for machine instr: " << *MI;
    403     report_fatal_error(Msg.str());
    404   }
    405 }
    406 
    407 /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
    408 /// instruction, using the specified assembler variant.  Targets should
    409 /// override this to format as appropriate.
    410 bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
    411                                  unsigned AsmVariant, const char *ExtraCode,
    412                                  raw_ostream &O) {
    413   // Target doesn't support this yet!
    414   return true;
    415 }
    416 
    417 bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
    418                                        unsigned AsmVariant,
    419                                        const char *ExtraCode, raw_ostream &O) {
    420   // Target doesn't support this yet!
    421   return true;
    422 }
    423 
    424