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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 #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(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<MCTargetAsmParser>
    126     TAP(TM.getTarget().createMCAsmParser(*STI, *Parser));
    127   if (!TAP)
    128     report_fatal_error("Inline asm not supported by this streamer because"
    129                        " we don't have an asm parser for this target\n");
    130   Parser->setTargetParser(*TAP.get());
    131 
    132   // Don't implicitly switch to the text section before the asm.
    133   int Res = Parser->Run(/*NoInitialTextSection*/ true,
    134                         /*NoFinalize*/ true);
    135   if (Res && !HasDiagHandler)
    136     report_fatal_error("Error parsing inline asm\n");
    137 #endif // ANDROID_TARGET_BUILD
    138 }
    139 
    140 
    141 /// EmitInlineAsm - This method formats and emits the specified machine
    142 /// instruction that is an inline asm.
    143 void AsmPrinter::EmitInlineAsm(const MachineInstr *MI) const {
    144 #ifndef ANDROID_TARGET_BUILD
    145   assert(MI->isInlineAsm() && "printInlineAsm only works on inline asms");
    146 
    147   unsigned NumOperands = MI->getNumOperands();
    148 
    149   // Count the number of register definitions to find the asm string.
    150   unsigned NumDefs = 0;
    151   for (; MI->getOperand(NumDefs).isReg() && MI->getOperand(NumDefs).isDef();
    152        ++NumDefs)
    153     assert(NumDefs != NumOperands-2 && "No asm string?");
    154 
    155   assert(MI->getOperand(NumDefs).isSymbol() && "No asm string?");
    156 
    157   // Disassemble the AsmStr, printing out the literal pieces, the operands, etc.
    158   const char *AsmStr = MI->getOperand(NumDefs).getSymbolName();
    159 
    160   // If this asmstr is empty, just print the #APP/#NOAPP markers.
    161   // These are useful to see where empty asm's wound up.
    162   if (AsmStr[0] == 0) {
    163     // Don't emit the comments if writing to a .o file.
    164     if (!OutStreamer.hasRawTextSupport()) return;
    165 
    166     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    167                             MAI->getInlineAsmStart());
    168     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    169                             MAI->getInlineAsmEnd());
    170     return;
    171   }
    172 
    173   // Emit the #APP start marker.  This has to happen even if verbose-asm isn't
    174   // enabled, so we use EmitRawText.
    175   if (OutStreamer.hasRawTextSupport())
    176     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    177                             MAI->getInlineAsmStart());
    178 
    179   // Get the !srcloc metadata node if we have it, and decode the loc cookie from
    180   // it.
    181   unsigned LocCookie = 0;
    182   const MDNode *LocMD = 0;
    183   for (unsigned i = MI->getNumOperands(); i != 0; --i) {
    184     if (MI->getOperand(i-1).isMetadata() &&
    185         (LocMD = MI->getOperand(i-1).getMetadata()) &&
    186         LocMD->getNumOperands() != 0) {
    187       if (const ConstantInt *CI = dyn_cast<ConstantInt>(LocMD->getOperand(0))) {
    188         LocCookie = CI->getZExtValue();
    189         break;
    190       }
    191     }
    192   }
    193 
    194   // Emit the inline asm to a temporary string so we can emit it through
    195   // EmitInlineAsm.
    196   SmallString<256> StringData;
    197   raw_svector_ostream OS(StringData);
    198 
    199   OS << '\t';
    200 
    201   // The variant of the current asmprinter.
    202   int AsmPrinterVariant = MAI->getAssemblerDialect();
    203 
    204   int CurVariant = -1;            // The number of the {.|.|.} region we are in.
    205   const char *LastEmitted = AsmStr; // One past the last character emitted.
    206 
    207   while (*LastEmitted) {
    208     switch (*LastEmitted) {
    209     default: {
    210       // Not a special case, emit the string section literally.
    211       const char *LiteralEnd = LastEmitted+1;
    212       while (*LiteralEnd && *LiteralEnd != '{' && *LiteralEnd != '|' &&
    213              *LiteralEnd != '}' && *LiteralEnd != '$' && *LiteralEnd != '\n')
    214         ++LiteralEnd;
    215       if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    216         OS.write(LastEmitted, LiteralEnd-LastEmitted);
    217       LastEmitted = LiteralEnd;
    218       break;
    219     }
    220     case '\n':
    221       ++LastEmitted;   // Consume newline character.
    222       OS << '\n';      // Indent code with newline.
    223       break;
    224     case '$': {
    225       ++LastEmitted;   // Consume '$' character.
    226       bool Done = true;
    227 
    228       // Handle escapes.
    229       switch (*LastEmitted) {
    230       default: Done = false; break;
    231       case '$':     // $$ -> $
    232         if (CurVariant == -1 || CurVariant == AsmPrinterVariant)
    233           OS << '$';
    234         ++LastEmitted;  // Consume second '$' character.
    235         break;
    236       case '(':             // $( -> same as GCC's { character.
    237         ++LastEmitted;      // Consume '(' character.
    238         if (CurVariant != -1)
    239           report_fatal_error("Nested variants found in inline asm string: '" +
    240                              Twine(AsmStr) + "'");
    241         CurVariant = 0;     // We're in the first variant now.
    242         break;
    243       case '|':
    244         ++LastEmitted;  // consume '|' character.
    245         if (CurVariant == -1)
    246           OS << '|';       // this is gcc's behavior for | outside a variant
    247         else
    248           ++CurVariant;   // We're in the next variant.
    249         break;
    250       case ')':         // $) -> same as GCC's } char.
    251         ++LastEmitted;  // consume ')' character.
    252         if (CurVariant == -1)
    253           OS << '}';     // this is gcc's behavior for } outside a variant
    254         else
    255           CurVariant = -1;
    256         break;
    257       }
    258       if (Done) break;
    259 
    260       bool HasCurlyBraces = false;
    261       if (*LastEmitted == '{') {     // ${variable}
    262         ++LastEmitted;               // Consume '{' character.
    263         HasCurlyBraces = true;
    264       }
    265 
    266       // If we have ${:foo}, then this is not a real operand reference, it is a
    267       // "magic" string reference, just like in .td files.  Arrange to call
    268       // PrintSpecial.
    269       if (HasCurlyBraces && *LastEmitted == ':') {
    270         ++LastEmitted;
    271         const char *StrStart = LastEmitted;
    272         const char *StrEnd = strchr(StrStart, '}');
    273         if (StrEnd == 0)
    274           report_fatal_error("Unterminated ${:foo} operand in inline asm"
    275                              " string: '" + Twine(AsmStr) + "'");
    276 
    277         std::string Val(StrStart, StrEnd);
    278         PrintSpecial(MI, OS, Val.c_str());
    279         LastEmitted = StrEnd+1;
    280         break;
    281       }
    282 
    283       const char *IDStart = LastEmitted;
    284       const char *IDEnd = IDStart;
    285       while (*IDEnd >= '0' && *IDEnd <= '9') ++IDEnd;
    286 
    287       unsigned Val;
    288       if (StringRef(IDStart, IDEnd-IDStart).getAsInteger(10, Val))
    289         report_fatal_error("Bad $ operand number in inline asm string: '" +
    290                            Twine(AsmStr) + "'");
    291       LastEmitted = IDEnd;
    292 
    293       char Modifier[2] = { 0, 0 };
    294 
    295       if (HasCurlyBraces) {
    296         // If we have curly braces, check for a modifier character.  This
    297         // supports syntax like ${0:u}, which correspond to "%u0" in GCC asm.
    298         if (*LastEmitted == ':') {
    299           ++LastEmitted;    // Consume ':' character.
    300           if (*LastEmitted == 0)
    301             report_fatal_error("Bad ${:} expression in inline asm string: '" +
    302                                Twine(AsmStr) + "'");
    303 
    304           Modifier[0] = *LastEmitted;
    305           ++LastEmitted;    // Consume modifier character.
    306         }
    307 
    308         if (*LastEmitted != '}')
    309           report_fatal_error("Bad ${} expression in inline asm string: '" +
    310                              Twine(AsmStr) + "'");
    311         ++LastEmitted;    // Consume '}' character.
    312       }
    313 
    314       if (Val >= NumOperands-1)
    315         report_fatal_error("Invalid $ operand number in inline asm string: '" +
    316                            Twine(AsmStr) + "'");
    317 
    318       // Okay, we finally have a value number.  Ask the target to print this
    319       // operand!
    320       if (CurVariant == -1 || CurVariant == AsmPrinterVariant) {
    321         unsigned OpNo = InlineAsm::MIOp_FirstOperand;
    322 
    323         bool Error = false;
    324 
    325         // Scan to find the machine operand number for the operand.
    326         for (; Val; --Val) {
    327           if (OpNo >= MI->getNumOperands()) break;
    328           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    329           OpNo += InlineAsm::getNumOperandRegisters(OpFlags) + 1;
    330         }
    331 
    332 	// We may have a location metadata attached to the end of the
    333 	// instruction, and at no point should see metadata at any
    334 	// other point while processing. It's an error if so.
    335         if (OpNo >= MI->getNumOperands() ||
    336 	    MI->getOperand(OpNo).isMetadata()) {
    337           Error = true;
    338         } else {
    339           unsigned OpFlags = MI->getOperand(OpNo).getImm();
    340           ++OpNo;  // Skip over the ID number.
    341 
    342           if (Modifier[0] == 'l')  // labels are target independent
    343             // FIXME: What if the operand isn't an MBB, report error?
    344             OS << *MI->getOperand(OpNo).getMBB()->getSymbol();
    345           else {
    346             AsmPrinter *AP = const_cast<AsmPrinter*>(this);
    347             if (InlineAsm::isMemKind(OpFlags)) {
    348               Error = AP->PrintAsmMemoryOperand(MI, OpNo, AsmPrinterVariant,
    349                                                 Modifier[0] ? Modifier : 0,
    350                                                 OS);
    351             } else {
    352               Error = AP->PrintAsmOperand(MI, OpNo, AsmPrinterVariant,
    353                                           Modifier[0] ? Modifier : 0, OS);
    354             }
    355           }
    356         }
    357         if (Error) {
    358           std::string msg;
    359           raw_string_ostream Msg(msg);
    360           Msg << "invalid operand in inline asm: '" << AsmStr << "'";
    361           MMI->getModule()->getContext().emitError(LocCookie, Msg.str());
    362         }
    363       }
    364       break;
    365     }
    366     }
    367   }
    368   OS << '\n' << (char)0;  // null terminate string.
    369   EmitInlineAsm(OS.str(), LocMD);
    370 
    371   // Emit the #NOAPP end marker.  This has to happen even if verbose-asm isn't
    372   // enabled, so we use EmitRawText.
    373   if (OutStreamer.hasRawTextSupport())
    374     OutStreamer.EmitRawText(Twine("\t")+MAI->getCommentString()+
    375                             MAI->getInlineAsmEnd());
    376 #endif // ANDROID_TARGET_BUILD
    377 }
    378 
    379 
    380 /// PrintSpecial - Print information related to the specified machine instr
    381 /// that is independent of the operand, and may be independent of the instr
    382 /// itself.  This can be useful for portably encoding the comment character
    383 /// or other bits of target-specific knowledge into the asmstrings.  The
    384 /// syntax used is ${:comment}.  Targets can override this to add support
    385 /// for their own strange codes.
    386 void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
    387                               const char *Code) const {
    388   if (!strcmp(Code, "private")) {
    389     OS << MAI->getPrivateGlobalPrefix();
    390   } else if (!strcmp(Code, "comment")) {
    391     OS << MAI->getCommentString();
    392   } else if (!strcmp(Code, "uid")) {
    393     // Comparing the address of MI isn't sufficient, because machineinstrs may
    394     // be allocated to the same address across functions.
    395 
    396     // If this is a new LastFn instruction, bump the counter.
    397     if (LastMI != MI || LastFn != getFunctionNumber()) {
    398       ++Counter;
    399       LastMI = MI;
    400       LastFn = getFunctionNumber();
    401     }
    402     OS << Counter;
    403   } else {
    404     std::string msg;
    405     raw_string_ostream Msg(msg);
    406     Msg << "Unknown special formatter '" << Code
    407          << "' for machine instr: " << *MI;
    408     report_fatal_error(Msg.str());
    409   }
    410 }
    411 
    412 /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
    413 /// instruction, using the specified assembler variant.  Targets should
    414 /// override this to format as appropriate.
    415 bool AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
    416                                  unsigned AsmVariant, const char *ExtraCode,
    417                                  raw_ostream &O) {
    418   // Target doesn't support this yet!
    419   return true;
    420 }
    421 
    422 bool AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
    423                                        unsigned AsmVariant,
    424                                        const char *ExtraCode, raw_ostream &O) {
    425   // Target doesn't support this yet!
    426   return true;
    427 }
    428 
    429