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      1 //===--- SemaStmtAsm.cpp - Semantic Analysis for Asm Statements -----------===//
      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 semantic analysis for inline asm statements.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "clang/Sema/SemaInternal.h"
     15 #include "clang/AST/RecordLayout.h"
     16 #include "clang/AST/TypeLoc.h"
     17 #include "clang/Basic/TargetInfo.h"
     18 #include "clang/Lex/Preprocessor.h"
     19 #include "clang/Sema/Initialization.h"
     20 #include "clang/Sema/Lookup.h"
     21 #include "clang/Sema/Scope.h"
     22 #include "clang/Sema/ScopeInfo.h"
     23 #include "llvm/ADT/ArrayRef.h"
     24 #include "llvm/ADT/BitVector.h"
     25 #include "llvm/ADT/SmallString.h"
     26 #include "llvm/MC/MCAsmInfo.h"
     27 #include "llvm/MC/MCContext.h"
     28 #include "llvm/MC/MCObjectFileInfo.h"
     29 #include "llvm/MC/MCParser/MCAsmParser.h"
     30 #include "llvm/MC/MCRegisterInfo.h"
     31 #include "llvm/MC/MCStreamer.h"
     32 #include "llvm/MC/MCSubtargetInfo.h"
     33 #include "llvm/MC/MCTargetAsmParser.h"
     34 #include "llvm/Support/SourceMgr.h"
     35 #include "llvm/Support/TargetRegistry.h"
     36 #include "llvm/Support/TargetSelect.h"
     37 using namespace clang;
     38 using namespace sema;
     39 
     40 /// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
     41 /// ignore "noop" casts in places where an lvalue is required by an inline asm.
     42 /// We emulate this behavior when -fheinous-gnu-extensions is specified, but
     43 /// provide a strong guidance to not use it.
     44 ///
     45 /// This method checks to see if the argument is an acceptable l-value and
     46 /// returns false if it is a case we can handle.
     47 static bool CheckAsmLValue(const Expr *E, Sema &S) {
     48   // Type dependent expressions will be checked during instantiation.
     49   if (E->isTypeDependent())
     50     return false;
     51 
     52   if (E->isLValue())
     53     return false;  // Cool, this is an lvalue.
     54 
     55   // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
     56   // are supposed to allow.
     57   const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
     58   if (E != E2 && E2->isLValue()) {
     59     if (!S.getLangOpts().HeinousExtensions)
     60       S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
     61         << E->getSourceRange();
     62     else
     63       S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
     64         << E->getSourceRange();
     65     // Accept, even if we emitted an error diagnostic.
     66     return false;
     67   }
     68 
     69   // None of the above, just randomly invalid non-lvalue.
     70   return true;
     71 }
     72 
     73 /// isOperandMentioned - Return true if the specified operand # is mentioned
     74 /// anywhere in the decomposed asm string.
     75 static bool isOperandMentioned(unsigned OpNo,
     76                          ArrayRef<GCCAsmStmt::AsmStringPiece> AsmStrPieces) {
     77   for (unsigned p = 0, e = AsmStrPieces.size(); p != e; ++p) {
     78     const GCCAsmStmt::AsmStringPiece &Piece = AsmStrPieces[p];
     79     if (!Piece.isOperand()) continue;
     80 
     81     // If this is a reference to the input and if the input was the smaller
     82     // one, then we have to reject this asm.
     83     if (Piece.getOperandNo() == OpNo)
     84       return true;
     85   }
     86   return false;
     87 }
     88 
     89 StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
     90                                  bool IsVolatile, unsigned NumOutputs,
     91                                  unsigned NumInputs, IdentifierInfo **Names,
     92                                  MultiExprArg constraints, MultiExprArg exprs,
     93                                  Expr *asmString, MultiExprArg clobbers,
     94                                  SourceLocation RParenLoc) {
     95   unsigned NumClobbers = clobbers.size();
     96   StringLiteral **Constraints =
     97     reinterpret_cast<StringLiteral**>(constraints.data());
     98   Expr **Exprs = exprs.data();
     99   StringLiteral *AsmString = cast<StringLiteral>(asmString);
    100   StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.data());
    101 
    102   SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
    103 
    104   // The parser verifies that there is a string literal here.
    105   if (!AsmString->isAscii())
    106     return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
    107       << AsmString->getSourceRange());
    108 
    109   for (unsigned i = 0; i != NumOutputs; i++) {
    110     StringLiteral *Literal = Constraints[i];
    111     if (!Literal->isAscii())
    112       return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
    113         << Literal->getSourceRange());
    114 
    115     StringRef OutputName;
    116     if (Names[i])
    117       OutputName = Names[i]->getName();
    118 
    119     TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
    120     if (!Context.getTargetInfo().validateOutputConstraint(Info))
    121       return StmtError(Diag(Literal->getLocStart(),
    122                             diag::err_asm_invalid_output_constraint)
    123                        << Info.getConstraintStr());
    124 
    125     // Check that the output exprs are valid lvalues.
    126     Expr *OutputExpr = Exprs[i];
    127     if (CheckAsmLValue(OutputExpr, *this)) {
    128       return StmtError(Diag(OutputExpr->getLocStart(),
    129                   diag::err_asm_invalid_lvalue_in_output)
    130         << OutputExpr->getSourceRange());
    131     }
    132 
    133     OutputConstraintInfos.push_back(Info);
    134   }
    135 
    136   SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
    137 
    138   for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
    139     StringLiteral *Literal = Constraints[i];
    140     if (!Literal->isAscii())
    141       return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
    142         << Literal->getSourceRange());
    143 
    144     StringRef InputName;
    145     if (Names[i])
    146       InputName = Names[i]->getName();
    147 
    148     TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
    149     if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos.data(),
    150                                                 NumOutputs, Info)) {
    151       return StmtError(Diag(Literal->getLocStart(),
    152                             diag::err_asm_invalid_input_constraint)
    153                        << Info.getConstraintStr());
    154     }
    155 
    156     Expr *InputExpr = Exprs[i];
    157 
    158     // Only allow void types for memory constraints.
    159     if (Info.allowsMemory() && !Info.allowsRegister()) {
    160       if (CheckAsmLValue(InputExpr, *this))
    161         return StmtError(Diag(InputExpr->getLocStart(),
    162                               diag::err_asm_invalid_lvalue_in_input)
    163                          << Info.getConstraintStr()
    164                          << InputExpr->getSourceRange());
    165     }
    166 
    167     if (Info.allowsRegister()) {
    168       if (InputExpr->getType()->isVoidType()) {
    169         return StmtError(Diag(InputExpr->getLocStart(),
    170                               diag::err_asm_invalid_type_in_input)
    171           << InputExpr->getType() << Info.getConstraintStr()
    172           << InputExpr->getSourceRange());
    173       }
    174     }
    175 
    176     ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
    177     if (Result.isInvalid())
    178       return StmtError();
    179 
    180     Exprs[i] = Result.take();
    181     InputConstraintInfos.push_back(Info);
    182 
    183     const Type *Ty = Exprs[i]->getType().getTypePtr();
    184     if (Ty->isDependentType() || Ty->isIncompleteType())
    185       continue;
    186 
    187     unsigned Size = Context.getTypeSize(Ty);
    188     if (!Context.getTargetInfo().validateInputSize(Literal->getString(),
    189                                                    Size))
    190       return StmtError(Diag(InputExpr->getLocStart(),
    191                             diag::err_asm_invalid_input_size)
    192                        << Info.getConstraintStr());
    193   }
    194 
    195   // Check that the clobbers are valid.
    196   for (unsigned i = 0; i != NumClobbers; i++) {
    197     StringLiteral *Literal = Clobbers[i];
    198     if (!Literal->isAscii())
    199       return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
    200         << Literal->getSourceRange());
    201 
    202     StringRef Clobber = Literal->getString();
    203 
    204     if (!Context.getTargetInfo().isValidClobber(Clobber))
    205       return StmtError(Diag(Literal->getLocStart(),
    206                   diag::err_asm_unknown_register_name) << Clobber);
    207   }
    208 
    209   GCCAsmStmt *NS =
    210     new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
    211                              NumInputs, Names, Constraints, Exprs, AsmString,
    212                              NumClobbers, Clobbers, RParenLoc);
    213   // Validate the asm string, ensuring it makes sense given the operands we
    214   // have.
    215   SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
    216   unsigned DiagOffs;
    217   if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
    218     Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
    219            << AsmString->getSourceRange();
    220     return StmtError();
    221   }
    222 
    223   // Validate constraints and modifiers.
    224   for (unsigned i = 0, e = Pieces.size(); i != e; ++i) {
    225     GCCAsmStmt::AsmStringPiece &Piece = Pieces[i];
    226     if (!Piece.isOperand()) continue;
    227 
    228     // Look for the correct constraint index.
    229     unsigned Idx = 0;
    230     unsigned ConstraintIdx = 0;
    231     for (unsigned i = 0, e = NS->getNumOutputs(); i != e; ++i, ++ConstraintIdx) {
    232       TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
    233       if (Idx == Piece.getOperandNo())
    234         break;
    235       ++Idx;
    236 
    237       if (Info.isReadWrite()) {
    238         if (Idx == Piece.getOperandNo())
    239           break;
    240         ++Idx;
    241       }
    242     }
    243 
    244     for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) {
    245       TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
    246       if (Idx == Piece.getOperandNo())
    247         break;
    248       ++Idx;
    249 
    250       if (Info.isReadWrite()) {
    251         if (Idx == Piece.getOperandNo())
    252           break;
    253         ++Idx;
    254       }
    255     }
    256 
    257     // Now that we have the right indexes go ahead and check.
    258     StringLiteral *Literal = Constraints[ConstraintIdx];
    259     const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr();
    260     if (Ty->isDependentType() || Ty->isIncompleteType())
    261       continue;
    262 
    263     unsigned Size = Context.getTypeSize(Ty);
    264     if (!Context.getTargetInfo()
    265           .validateConstraintModifier(Literal->getString(), Piece.getModifier(),
    266                                       Size))
    267       Diag(Exprs[ConstraintIdx]->getLocStart(),
    268            diag::warn_asm_mismatched_size_modifier);
    269   }
    270 
    271   // Validate tied input operands for type mismatches.
    272   for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
    273     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
    274 
    275     // If this is a tied constraint, verify that the output and input have
    276     // either exactly the same type, or that they are int/ptr operands with the
    277     // same size (int/long, int*/long, are ok etc).
    278     if (!Info.hasTiedOperand()) continue;
    279 
    280     unsigned TiedTo = Info.getTiedOperand();
    281     unsigned InputOpNo = i+NumOutputs;
    282     Expr *OutputExpr = Exprs[TiedTo];
    283     Expr *InputExpr = Exprs[InputOpNo];
    284 
    285     if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
    286       continue;
    287 
    288     QualType InTy = InputExpr->getType();
    289     QualType OutTy = OutputExpr->getType();
    290     if (Context.hasSameType(InTy, OutTy))
    291       continue;  // All types can be tied to themselves.
    292 
    293     // Decide if the input and output are in the same domain (integer/ptr or
    294     // floating point.
    295     enum AsmDomain {
    296       AD_Int, AD_FP, AD_Other
    297     } InputDomain, OutputDomain;
    298 
    299     if (InTy->isIntegerType() || InTy->isPointerType())
    300       InputDomain = AD_Int;
    301     else if (InTy->isRealFloatingType())
    302       InputDomain = AD_FP;
    303     else
    304       InputDomain = AD_Other;
    305 
    306     if (OutTy->isIntegerType() || OutTy->isPointerType())
    307       OutputDomain = AD_Int;
    308     else if (OutTy->isRealFloatingType())
    309       OutputDomain = AD_FP;
    310     else
    311       OutputDomain = AD_Other;
    312 
    313     // They are ok if they are the same size and in the same domain.  This
    314     // allows tying things like:
    315     //   void* to int*
    316     //   void* to int            if they are the same size.
    317     //   double to long double   if they are the same size.
    318     //
    319     uint64_t OutSize = Context.getTypeSize(OutTy);
    320     uint64_t InSize = Context.getTypeSize(InTy);
    321     if (OutSize == InSize && InputDomain == OutputDomain &&
    322         InputDomain != AD_Other)
    323       continue;
    324 
    325     // If the smaller input/output operand is not mentioned in the asm string,
    326     // then we can promote the smaller one to a larger input and the asm string
    327     // won't notice.
    328     bool SmallerValueMentioned = false;
    329 
    330     // If this is a reference to the input and if the input was the smaller
    331     // one, then we have to reject this asm.
    332     if (isOperandMentioned(InputOpNo, Pieces)) {
    333       // This is a use in the asm string of the smaller operand.  Since we
    334       // codegen this by promoting to a wider value, the asm will get printed
    335       // "wrong".
    336       SmallerValueMentioned |= InSize < OutSize;
    337     }
    338     if (isOperandMentioned(TiedTo, Pieces)) {
    339       // If this is a reference to the output, and if the output is the larger
    340       // value, then it's ok because we'll promote the input to the larger type.
    341       SmallerValueMentioned |= OutSize < InSize;
    342     }
    343 
    344     // If the smaller value wasn't mentioned in the asm string, and if the
    345     // output was a register, just extend the shorter one to the size of the
    346     // larger one.
    347     if (!SmallerValueMentioned && InputDomain != AD_Other &&
    348         OutputConstraintInfos[TiedTo].allowsRegister())
    349       continue;
    350 
    351     // Either both of the operands were mentioned or the smaller one was
    352     // mentioned.  One more special case that we'll allow: if the tied input is
    353     // integer, unmentioned, and is a constant, then we'll allow truncating it
    354     // down to the size of the destination.
    355     if (InputDomain == AD_Int && OutputDomain == AD_Int &&
    356         !isOperandMentioned(InputOpNo, Pieces) &&
    357         InputExpr->isEvaluatable(Context)) {
    358       CastKind castKind =
    359         (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast);
    360       InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).take();
    361       Exprs[InputOpNo] = InputExpr;
    362       NS->setInputExpr(i, InputExpr);
    363       continue;
    364     }
    365 
    366     Diag(InputExpr->getLocStart(),
    367          diag::err_asm_tying_incompatible_types)
    368       << InTy << OutTy << OutputExpr->getSourceRange()
    369       << InputExpr->getSourceRange();
    370     return StmtError();
    371   }
    372 
    373   return Owned(NS);
    374 }
    375 
    376 // getSpelling - Get the spelling of the AsmTok token.
    377 static StringRef getSpelling(Sema &SemaRef, Token AsmTok) {
    378   StringRef Asm;
    379   SmallString<512> TokenBuf;
    380   TokenBuf.resize(512);
    381   bool StringInvalid = false;
    382   Asm = SemaRef.PP.getSpelling(AsmTok, TokenBuf, &StringInvalid);
    383   assert (!StringInvalid && "Expected valid string!");
    384   return Asm;
    385 }
    386 
    387 // Build the inline assembly string.  Returns true on error.
    388 static bool buildMSAsmString(Sema &SemaRef,
    389                              SourceLocation AsmLoc,
    390                              ArrayRef<Token> AsmToks,
    391                              SmallVectorImpl<unsigned> &TokOffsets,
    392                              std::string &AsmString) {
    393   assert (!AsmToks.empty() && "Didn't expect an empty AsmToks!");
    394 
    395   SmallString<512> Asm;
    396   for (unsigned i = 0, e = AsmToks.size(); i < e; ++i) {
    397     bool isNewAsm = ((i == 0) ||
    398                      AsmToks[i].isAtStartOfLine() ||
    399                      AsmToks[i].is(tok::kw_asm));
    400     if (isNewAsm) {
    401       if (i != 0)
    402         Asm += "\n\t";
    403 
    404       if (AsmToks[i].is(tok::kw_asm)) {
    405         i++; // Skip __asm
    406         if (i == e) {
    407           SemaRef.Diag(AsmLoc, diag::err_asm_empty);
    408           return true;
    409         }
    410 
    411       }
    412     }
    413 
    414     if (i && AsmToks[i].hasLeadingSpace() && !isNewAsm)
    415       Asm += ' ';
    416 
    417     StringRef Spelling = getSpelling(SemaRef, AsmToks[i]);
    418     Asm += Spelling;
    419     TokOffsets.push_back(Asm.size());
    420   }
    421   AsmString = Asm.str();
    422   return false;
    423 }
    424 
    425 namespace {
    426 
    427 class MCAsmParserSemaCallbackImpl : public llvm::MCAsmParserSemaCallback {
    428   Sema &SemaRef;
    429   SourceLocation AsmLoc;
    430   ArrayRef<Token> AsmToks;
    431   ArrayRef<unsigned> TokOffsets;
    432 
    433 public:
    434   MCAsmParserSemaCallbackImpl(Sema &Ref, SourceLocation Loc,
    435                               ArrayRef<Token> Toks,
    436                               ArrayRef<unsigned> Offsets)
    437     : SemaRef(Ref), AsmLoc(Loc), AsmToks(Toks), TokOffsets(Offsets) { }
    438   ~MCAsmParserSemaCallbackImpl() {}
    439 
    440   void *LookupInlineAsmIdentifier(StringRef Name, void *SrcLoc,
    441                                   unsigned &Length, unsigned &Size,
    442                                   unsigned &Type, bool &IsVarDecl){
    443     SourceLocation Loc = SourceLocation::getFromPtrEncoding(SrcLoc);
    444 
    445     NamedDecl *OpDecl = SemaRef.LookupInlineAsmIdentifier(Name, Loc, Length,
    446                                                           Size, Type,
    447                                                           IsVarDecl);
    448     return static_cast<void *>(OpDecl);
    449   }
    450 
    451   bool LookupInlineAsmField(StringRef Base, StringRef Member,
    452                             unsigned &Offset) {
    453     return SemaRef.LookupInlineAsmField(Base, Member, Offset, AsmLoc);
    454   }
    455 
    456   static void MSAsmDiagHandlerCallback(const llvm::SMDiagnostic &D,
    457                                        void *Context) {
    458     ((MCAsmParserSemaCallbackImpl*)Context)->MSAsmDiagHandler(D);
    459   }
    460   void MSAsmDiagHandler(const llvm::SMDiagnostic &D) {
    461     // Compute an offset into the inline asm buffer.
    462     // FIXME: This isn't right if .macro is involved (but hopefully, no
    463     // real-world code does that).
    464     const llvm::SourceMgr &LSM = *D.getSourceMgr();
    465     const llvm::MemoryBuffer *LBuf =
    466     LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(D.getLoc()));
    467     unsigned Offset = D.getLoc().getPointer()  - LBuf->getBufferStart();
    468 
    469     // Figure out which token that offset points into.
    470     const unsigned *OffsetPtr =
    471         std::lower_bound(TokOffsets.begin(), TokOffsets.end(), Offset);
    472     unsigned TokIndex = OffsetPtr - TokOffsets.begin();
    473 
    474     // If we come up with an answer which seems sane, use it; otherwise,
    475     // just point at the __asm keyword.
    476     // FIXME: Assert the answer is sane once we handle .macro correctly.
    477     SourceLocation Loc = AsmLoc;
    478     if (TokIndex < AsmToks.size()) {
    479       const Token *Tok = &AsmToks[TokIndex];
    480       Loc = Tok->getLocation();
    481       Loc = Loc.getLocWithOffset(Offset - (*OffsetPtr - Tok->getLength()));
    482     }
    483     SemaRef.Diag(Loc, diag::err_inline_ms_asm_parsing) << D.getMessage();
    484   }
    485 };
    486 
    487 }
    488 
    489 NamedDecl *Sema::LookupInlineAsmIdentifier(StringRef Name, SourceLocation Loc,
    490                                            unsigned &Length, unsigned &Size,
    491                                            unsigned &Type, bool &IsVarDecl) {
    492   Length = 1;
    493   Size = 0;
    494   Type = 0;
    495   IsVarDecl = false;
    496   LookupResult Result(*this, &Context.Idents.get(Name), Loc,
    497                       Sema::LookupOrdinaryName);
    498 
    499   if (!LookupName(Result, getCurScope())) {
    500     // If we don't find anything, return null; the AsmParser will assume
    501     // it is a label of some sort.
    502     return 0;
    503   }
    504 
    505   if (!Result.isSingleResult()) {
    506     // FIXME: Diagnose result.
    507     return 0;
    508   }
    509 
    510   NamedDecl *ND = Result.getFoundDecl();
    511   if (isa<VarDecl>(ND) || isa<FunctionDecl>(ND)) {
    512     if (VarDecl *Var = dyn_cast<VarDecl>(ND)) {
    513       Type = Context.getTypeInfo(Var->getType()).first;
    514       QualType Ty = Var->getType();
    515       if (Ty->isArrayType()) {
    516         const ArrayType *ATy = Context.getAsArrayType(Ty);
    517         Length = Type / Context.getTypeInfo(ATy->getElementType()).first;
    518         Type /= Length; // Type is in terms of a single element.
    519       }
    520       Type /= 8; // Type is in terms of bits, but we want bytes.
    521       Size = Length * Type;
    522       IsVarDecl = true;
    523     }
    524     return ND;
    525   }
    526 
    527   // FIXME: Handle other kinds of results? (FieldDecl, etc.)
    528   // FIXME: Diagnose if we find something we can't handle, like a typedef.
    529   return 0;
    530 }
    531 
    532 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
    533                                 unsigned &Offset, SourceLocation AsmLoc) {
    534   Offset = 0;
    535   LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
    536                           LookupOrdinaryName);
    537 
    538   if (!LookupName(BaseResult, getCurScope()))
    539     return true;
    540 
    541   if (!BaseResult.isSingleResult())
    542     return true;
    543 
    544   NamedDecl *FoundDecl = BaseResult.getFoundDecl();
    545   const RecordType *RT = 0;
    546   if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl)) {
    547     RT = VD->getType()->getAs<RecordType>();
    548   } else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(FoundDecl)) {
    549     RT = TD->getUnderlyingType()->getAs<RecordType>();
    550   }
    551   if (!RT)
    552     return true;
    553 
    554   if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0))
    555     return true;
    556 
    557   LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(),
    558                            LookupMemberName);
    559 
    560   if (!LookupQualifiedName(FieldResult, RT->getDecl()))
    561     return true;
    562 
    563   // FIXME: Handle IndirectFieldDecl?
    564   FieldDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
    565   if (!FD)
    566     return true;
    567 
    568   const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
    569   unsigned i = FD->getFieldIndex();
    570   CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
    571   Offset = (unsigned)Result.getQuantity();
    572 
    573   return false;
    574 }
    575 
    576 StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
    577                                 ArrayRef<Token> AsmToks,SourceLocation EndLoc) {
    578   SmallVector<IdentifierInfo*, 4> Names;
    579   SmallVector<StringRef, 4> ConstraintRefs;
    580   SmallVector<Expr*, 4> Exprs;
    581   SmallVector<StringRef, 4> ClobberRefs;
    582 
    583   llvm::Triple TheTriple = Context.getTargetInfo().getTriple();
    584   llvm::Triple::ArchType ArchTy = TheTriple.getArch();
    585   bool UnsupportedArch = ArchTy != llvm::Triple::x86 &&
    586     ArchTy != llvm::Triple::x86_64;
    587   if (UnsupportedArch)
    588     Diag(AsmLoc, diag::err_msasm_unsupported_arch) << TheTriple.getArchName();
    589 
    590   // Empty asm statements don't need to instantiate the AsmParser, etc.
    591   if (UnsupportedArch || AsmToks.empty()) {
    592     StringRef EmptyAsmStr;
    593     MSAsmStmt *NS =
    594       new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, /*IsSimple*/ true,
    595                               /*IsVolatile*/ true, AsmToks, /*NumOutputs*/ 0,
    596                               /*NumInputs*/ 0, Names, ConstraintRefs, Exprs,
    597                               EmptyAsmStr, ClobberRefs, EndLoc);
    598     return Owned(NS);
    599   }
    600 
    601   std::string AsmString;
    602   SmallVector<unsigned, 8> TokOffsets;
    603   if (buildMSAsmString(*this, AsmLoc, AsmToks, TokOffsets, AsmString))
    604     return StmtError();
    605 
    606   // Get the target specific parser.
    607   std::string Error;
    608   const std::string &TT = TheTriple.getTriple();
    609   const llvm::Target *TheTarget(llvm::TargetRegistry::lookupTarget(TT, Error));
    610 
    611   OwningPtr<llvm::MCAsmInfo> MAI(TheTarget->createMCAsmInfo(TT));
    612   OwningPtr<llvm::MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TT));
    613   OwningPtr<llvm::MCObjectFileInfo> MOFI(new llvm::MCObjectFileInfo());
    614   OwningPtr<llvm::MCSubtargetInfo>
    615     STI(TheTarget->createMCSubtargetInfo(TT, "", ""));
    616 
    617   llvm::SourceMgr SrcMgr;
    618   llvm::MCContext Ctx(*MAI, *MRI, MOFI.get(), &SrcMgr);
    619   llvm::MemoryBuffer *Buffer =
    620     llvm::MemoryBuffer::getMemBuffer(AsmString, "<inline asm>");
    621 
    622   // Tell SrcMgr about this buffer, which is what the parser will pick up.
    623   SrcMgr.AddNewSourceBuffer(Buffer, llvm::SMLoc());
    624 
    625   OwningPtr<llvm::MCStreamer> Str(createNullStreamer(Ctx));
    626   OwningPtr<llvm::MCAsmParser>
    627     Parser(createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
    628   OwningPtr<llvm::MCTargetAsmParser>
    629     TargetParser(TheTarget->createMCAsmParser(*STI, *Parser));
    630 
    631   // Get the instruction descriptor.
    632   const llvm::MCInstrInfo *MII = TheTarget->createMCInstrInfo();
    633   llvm::MCInstPrinter *IP =
    634     TheTarget->createMCInstPrinter(1, *MAI, *MII, *MRI, *STI);
    635 
    636   // Change to the Intel dialect.
    637   Parser->setAssemblerDialect(1);
    638   Parser->setTargetParser(*TargetParser.get());
    639   Parser->setParsingInlineAsm(true);
    640   TargetParser->setParsingInlineAsm(true);
    641 
    642   MCAsmParserSemaCallbackImpl MCAPSI(*this, AsmLoc, AsmToks, TokOffsets);
    643   TargetParser->setSemaCallback(&MCAPSI);
    644   SrcMgr.setDiagHandler(MCAsmParserSemaCallbackImpl::MSAsmDiagHandlerCallback,
    645                         &MCAPSI);
    646 
    647   unsigned NumOutputs;
    648   unsigned NumInputs;
    649   std::string AsmStringIR;
    650   SmallVector<std::pair<void *, bool>, 4> OpDecls;
    651   SmallVector<std::string, 4> Constraints;
    652   SmallVector<std::string, 4> Clobbers;
    653   if (Parser->parseMSInlineAsm(AsmLoc.getPtrEncoding(), AsmStringIR,
    654                                NumOutputs, NumInputs, OpDecls, Constraints,
    655                                Clobbers, MII, IP, MCAPSI))
    656     return StmtError();
    657 
    658   // Build the vector of clobber StringRefs.
    659   unsigned NumClobbers = Clobbers.size();
    660   ClobberRefs.resize(NumClobbers);
    661   for (unsigned i = 0; i != NumClobbers; ++i)
    662     ClobberRefs[i] = StringRef(Clobbers[i]);
    663 
    664   // Recast the void pointers and build the vector of constraint StringRefs.
    665   unsigned NumExprs = NumOutputs + NumInputs;
    666   Names.resize(NumExprs);
    667   ConstraintRefs.resize(NumExprs);
    668   Exprs.resize(NumExprs);
    669   for (unsigned i = 0, e = NumExprs; i != e; ++i) {
    670     NamedDecl *OpDecl = static_cast<NamedDecl *>(OpDecls[i].first);
    671     if (!OpDecl)
    672       return StmtError();
    673 
    674     DeclarationNameInfo NameInfo(OpDecl->getDeclName(), AsmLoc);
    675     ExprResult OpExpr = BuildDeclarationNameExpr(CXXScopeSpec(), NameInfo,
    676                                                  OpDecl);
    677     if (OpExpr.isInvalid())
    678       return StmtError();
    679 
    680     // Need address of variable.
    681     if (OpDecls[i].second)
    682       OpExpr = BuildUnaryOp(getCurScope(), AsmLoc, clang::UO_AddrOf,
    683                             OpExpr.take());
    684 
    685     Names[i] = OpDecl->getIdentifier();
    686     ConstraintRefs[i] = StringRef(Constraints[i]);
    687     Exprs[i] = OpExpr.take();
    688   }
    689 
    690   bool IsSimple = NumExprs > 0;
    691   MSAsmStmt *NS =
    692     new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
    693                             /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
    694                             Names, ConstraintRefs, Exprs, AsmStringIR,
    695                             ClobberRefs, EndLoc);
    696   return Owned(NS);
    697 }
    698