SemaStmtAsm.cpp revision 1e7ca6211c77208c8a339c2a26e612be81c70ec5 
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"
37using namespace clang;
38using 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.
47static 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.
75static 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
89StmtResult 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    if (RequireCompleteType(OutputExpr->getLocStart(), Exprs[i]->getType(),
133                            diag::err_dereference_incomplete_type))
134      return StmtError();
135
136    OutputConstraintInfos.push_back(Info);
137  }
138
139  SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
140
141  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
142    StringLiteral *Literal = Constraints[i];
143    if (!Literal->isAscii())
144      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
145        << Literal->getSourceRange());
146
147    StringRef InputName;
148    if (Names[i])
149      InputName = Names[i]->getName();
150
151    TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
152    if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos.data(),
153                                                NumOutputs, Info)) {
154      return StmtError(Diag(Literal->getLocStart(),
155                            diag::err_asm_invalid_input_constraint)
156                       << Info.getConstraintStr());
157    }
158
159    Expr *InputExpr = Exprs[i];
160
161    // Only allow void types for memory constraints.
162    if (Info.allowsMemory() && !Info.allowsRegister()) {
163      if (CheckAsmLValue(InputExpr, *this))
164        return StmtError(Diag(InputExpr->getLocStart(),
165                              diag::err_asm_invalid_lvalue_in_input)
166                         << Info.getConstraintStr()
167                         << InputExpr->getSourceRange());
168    }
169
170    if (Info.allowsRegister()) {
171      if (InputExpr->getType()->isVoidType()) {
172        return StmtError(Diag(InputExpr->getLocStart(),
173                              diag::err_asm_invalid_type_in_input)
174          << InputExpr->getType() << Info.getConstraintStr()
175          << InputExpr->getSourceRange());
176      }
177    }
178
179    ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
180    if (Result.isInvalid())
181      return StmtError();
182
183    Exprs[i] = Result.take();
184    InputConstraintInfos.push_back(Info);
185
186    const Type *Ty = Exprs[i]->getType().getTypePtr();
187    if (Ty->isDependentType())
188      continue;
189
190    if (!Ty->isVoidType() || !Info.allowsMemory())
191      if (RequireCompleteType(InputExpr->getLocStart(), Exprs[i]->getType(),
192                              diag::err_dereference_incomplete_type))
193        return StmtError();
194
195    unsigned Size = Context.getTypeSize(Ty);
196    if (!Context.getTargetInfo().validateInputSize(Literal->getString(),
197                                                   Size))
198      return StmtError(Diag(InputExpr->getLocStart(),
199                            diag::err_asm_invalid_input_size)
200                       << Info.getConstraintStr());
201  }
202
203  // Check that the clobbers are valid.
204  for (unsigned i = 0; i != NumClobbers; i++) {
205    StringLiteral *Literal = Clobbers[i];
206    if (!Literal->isAscii())
207      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
208        << Literal->getSourceRange());
209
210    StringRef Clobber = Literal->getString();
211
212    if (!Context.getTargetInfo().isValidClobber(Clobber))
213      return StmtError(Diag(Literal->getLocStart(),
214                  diag::err_asm_unknown_register_name) << Clobber);
215  }
216
217  GCCAsmStmt *NS =
218    new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
219                             NumInputs, Names, Constraints, Exprs, AsmString,
220                             NumClobbers, Clobbers, RParenLoc);
221  // Validate the asm string, ensuring it makes sense given the operands we
222  // have.
223  SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
224  unsigned DiagOffs;
225  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
226    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
227           << AsmString->getSourceRange();
228    return StmtError();
229  }
230
231  // Validate constraints and modifiers.
232  for (unsigned i = 0, e = Pieces.size(); i != e; ++i) {
233    GCCAsmStmt::AsmStringPiece &Piece = Pieces[i];
234    if (!Piece.isOperand()) continue;
235
236    // Look for the correct constraint index.
237    unsigned Idx = 0;
238    unsigned ConstraintIdx = 0;
239    for (unsigned i = 0, e = NS->getNumOutputs(); i != e; ++i, ++ConstraintIdx) {
240      TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
241      if (Idx == Piece.getOperandNo())
242        break;
243      ++Idx;
244
245      if (Info.isReadWrite()) {
246        if (Idx == Piece.getOperandNo())
247          break;
248        ++Idx;
249      }
250    }
251
252    for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) {
253      TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
254      if (Idx == Piece.getOperandNo())
255        break;
256      ++Idx;
257
258      if (Info.isReadWrite()) {
259        if (Idx == Piece.getOperandNo())
260          break;
261        ++Idx;
262      }
263    }
264
265    // Now that we have the right indexes go ahead and check.
266    StringLiteral *Literal = Constraints[ConstraintIdx];
267    const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr();
268    if (Ty->isDependentType() || Ty->isIncompleteType())
269      continue;
270
271    unsigned Size = Context.getTypeSize(Ty);
272    if (!Context.getTargetInfo()
273          .validateConstraintModifier(Literal->getString(), Piece.getModifier(),
274                                      Size))
275      Diag(Exprs[ConstraintIdx]->getLocStart(),
276           diag::warn_asm_mismatched_size_modifier);
277  }
278
279  // Validate tied input operands for type mismatches.
280  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
281    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
282
283    // If this is a tied constraint, verify that the output and input have
284    // either exactly the same type, or that they are int/ptr operands with the
285    // same size (int/long, int*/long, are ok etc).
286    if (!Info.hasTiedOperand()) continue;
287
288    unsigned TiedTo = Info.getTiedOperand();
289    unsigned InputOpNo = i+NumOutputs;
290    Expr *OutputExpr = Exprs[TiedTo];
291    Expr *InputExpr = Exprs[InputOpNo];
292
293    if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
294      continue;
295
296    QualType InTy = InputExpr->getType();
297    QualType OutTy = OutputExpr->getType();
298    if (Context.hasSameType(InTy, OutTy))
299      continue;  // All types can be tied to themselves.
300
301    // Decide if the input and output are in the same domain (integer/ptr or
302    // floating point.
303    enum AsmDomain {
304      AD_Int, AD_FP, AD_Other
305    } InputDomain, OutputDomain;
306
307    if (InTy->isIntegerType() || InTy->isPointerType())
308      InputDomain = AD_Int;
309    else if (InTy->isRealFloatingType())
310      InputDomain = AD_FP;
311    else
312      InputDomain = AD_Other;
313
314    if (OutTy->isIntegerType() || OutTy->isPointerType())
315      OutputDomain = AD_Int;
316    else if (OutTy->isRealFloatingType())
317      OutputDomain = AD_FP;
318    else
319      OutputDomain = AD_Other;
320
321    // They are ok if they are the same size and in the same domain.  This
322    // allows tying things like:
323    //   void* to int*
324    //   void* to int            if they are the same size.
325    //   double to long double   if they are the same size.
326    //
327    uint64_t OutSize = Context.getTypeSize(OutTy);
328    uint64_t InSize = Context.getTypeSize(InTy);
329    if (OutSize == InSize && InputDomain == OutputDomain &&
330        InputDomain != AD_Other)
331      continue;
332
333    // If the smaller input/output operand is not mentioned in the asm string,
334    // then we can promote the smaller one to a larger input and the asm string
335    // won't notice.
336    bool SmallerValueMentioned = false;
337
338    // If this is a reference to the input and if the input was the smaller
339    // one, then we have to reject this asm.
340    if (isOperandMentioned(InputOpNo, Pieces)) {
341      // This is a use in the asm string of the smaller operand.  Since we
342      // codegen this by promoting to a wider value, the asm will get printed
343      // "wrong".
344      SmallerValueMentioned |= InSize < OutSize;
345    }
346    if (isOperandMentioned(TiedTo, Pieces)) {
347      // If this is a reference to the output, and if the output is the larger
348      // value, then it's ok because we'll promote the input to the larger type.
349      SmallerValueMentioned |= OutSize < InSize;
350    }
351
352    // If the smaller value wasn't mentioned in the asm string, and if the
353    // output was a register, just extend the shorter one to the size of the
354    // larger one.
355    if (!SmallerValueMentioned && InputDomain != AD_Other &&
356        OutputConstraintInfos[TiedTo].allowsRegister())
357      continue;
358
359    // Either both of the operands were mentioned or the smaller one was
360    // mentioned.  One more special case that we'll allow: if the tied input is
361    // integer, unmentioned, and is a constant, then we'll allow truncating it
362    // down to the size of the destination.
363    if (InputDomain == AD_Int && OutputDomain == AD_Int &&
364        !isOperandMentioned(InputOpNo, Pieces) &&
365        InputExpr->isEvaluatable(Context)) {
366      CastKind castKind =
367        (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast);
368      InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).take();
369      Exprs[InputOpNo] = InputExpr;
370      NS->setInputExpr(i, InputExpr);
371      continue;
372    }
373
374    Diag(InputExpr->getLocStart(),
375         diag::err_asm_tying_incompatible_types)
376      << InTy << OutTy << OutputExpr->getSourceRange()
377      << InputExpr->getSourceRange();
378    return StmtError();
379  }
380
381  return Owned(NS);
382}
383
384// getSpelling - Get the spelling of the AsmTok token.
385static StringRef getSpelling(Sema &SemaRef, Token AsmTok) {
386  StringRef Asm;
387  SmallString<512> TokenBuf;
388  TokenBuf.resize(512);
389  bool StringInvalid = false;
390  Asm = SemaRef.PP.getSpelling(AsmTok, TokenBuf, &StringInvalid);
391  assert (!StringInvalid && "Expected valid string!");
392  return Asm;
393}
394
395// Build the inline assembly string.  Returns true on error.
396static bool buildMSAsmString(Sema &SemaRef,
397                             SourceLocation AsmLoc,
398                             ArrayRef<Token> AsmToks,
399                             SmallVectorImpl<unsigned> &TokOffsets,
400                             std::string &AsmString) {
401  assert (!AsmToks.empty() && "Didn't expect an empty AsmToks!");
402
403  SmallString<512> Asm;
404  for (unsigned i = 0, e = AsmToks.size(); i < e; ++i) {
405    bool isNewAsm = ((i == 0) ||
406                     AsmToks[i].isAtStartOfLine() ||
407                     AsmToks[i].is(tok::kw_asm));
408    if (isNewAsm) {
409      if (i != 0)
410        Asm += "\n\t";
411
412      if (AsmToks[i].is(tok::kw_asm)) {
413        i++; // Skip __asm
414        if (i == e) {
415          SemaRef.Diag(AsmLoc, diag::err_asm_empty);
416          return true;
417        }
418
419      }
420    }
421
422    if (i && AsmToks[i].hasLeadingSpace() && !isNewAsm)
423      Asm += ' ';
424
425    StringRef Spelling = getSpelling(SemaRef, AsmToks[i]);
426    Asm += Spelling;
427    TokOffsets.push_back(Asm.size());
428  }
429  AsmString = Asm.str();
430  return false;
431}
432
433namespace {
434
435class MCAsmParserSemaCallbackImpl : public llvm::MCAsmParserSemaCallback {
436  Sema &SemaRef;
437  SourceLocation AsmLoc;
438  ArrayRef<Token> AsmToks;
439  ArrayRef<unsigned> TokOffsets;
440
441public:
442  MCAsmParserSemaCallbackImpl(Sema &Ref, SourceLocation Loc,
443                              ArrayRef<Token> Toks,
444                              ArrayRef<unsigned> Offsets)
445    : SemaRef(Ref), AsmLoc(Loc), AsmToks(Toks), TokOffsets(Offsets) { }
446  ~MCAsmParserSemaCallbackImpl() {}
447
448  void *LookupInlineAsmIdentifier(StringRef &LineBuf,
449                                  InlineAsmIdentifierInfo &Info) {
450    SourceLocation Loc = SourceLocation::getFromPtrEncoding(LineBuf.data());
451    NamedDecl *OpDecl = SemaRef.LookupInlineAsmIdentifier(LineBuf, Loc, Info);
452    return static_cast<void *>(OpDecl);
453  }
454
455  bool LookupInlineAsmField(StringRef Base, StringRef Member,
456                            unsigned &Offset) {
457    return SemaRef.LookupInlineAsmField(Base, Member, Offset, AsmLoc);
458  }
459
460  static void MSAsmDiagHandlerCallback(const llvm::SMDiagnostic &D,
461                                       void *Context) {
462    ((MCAsmParserSemaCallbackImpl*)Context)->MSAsmDiagHandler(D);
463  }
464  void MSAsmDiagHandler(const llvm::SMDiagnostic &D) {
465    // Compute an offset into the inline asm buffer.
466    // FIXME: This isn't right if .macro is involved (but hopefully, no
467    // real-world code does that).
468    const llvm::SourceMgr &LSM = *D.getSourceMgr();
469    const llvm::MemoryBuffer *LBuf =
470    LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(D.getLoc()));
471    unsigned Offset = D.getLoc().getPointer()  - LBuf->getBufferStart();
472
473    // Figure out which token that offset points into.
474    const unsigned *OffsetPtr =
475        std::lower_bound(TokOffsets.begin(), TokOffsets.end(), Offset);
476    unsigned TokIndex = OffsetPtr - TokOffsets.begin();
477
478    // If we come up with an answer which seems sane, use it; otherwise,
479    // just point at the __asm keyword.
480    // FIXME: Assert the answer is sane once we handle .macro correctly.
481    SourceLocation Loc = AsmLoc;
482    if (TokIndex < AsmToks.size()) {
483      const Token *Tok = &AsmToks[TokIndex];
484      Loc = Tok->getLocation();
485      Loc = Loc.getLocWithOffset(Offset - (*OffsetPtr - Tok->getLength()));
486    }
487    SemaRef.Diag(Loc, diag::err_inline_ms_asm_parsing) << D.getMessage();
488  }
489};
490
491}
492
493// FIXME: Temporary hack until the frontend parser is hooked up to parse
494// variables.
495static bool isIdentifierChar(char c) {
496  return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@';
497}
498
499static void lexIdentifier(const char *&CurPtr) {
500  while (isIdentifierChar(*CurPtr))
501    ++CurPtr;
502}
503
504static StringRef parseIdentifier(StringRef Identifier) {
505  const char *StartPtr = Identifier.data(), *EndPtr, *CurPtr;
506  EndPtr = StartPtr + Identifier.size();
507  CurPtr = StartPtr;
508  while(CurPtr <= EndPtr) {
509    if (isIdentifierChar(*CurPtr))
510      lexIdentifier(CurPtr);
511    else if (CurPtr[0] == ':' && CurPtr[1] == ':')
512      CurPtr += 2;
513    else
514      break;
515  }
516  return StringRef(StartPtr, CurPtr - StartPtr);
517}
518
519NamedDecl *Sema::LookupInlineAsmIdentifier(StringRef &LineBuf, SourceLocation Loc,
520                                           InlineAsmIdentifierInfo &Info) {
521  Info.clear();
522  // FIXME: Temporary hack until the frontend parser is hooked up to parse
523  // variables.
524  LineBuf = parseIdentifier(LineBuf);
525  LookupResult Result(*this, &Context.Idents.get(LineBuf), Loc,
526                      Sema::LookupOrdinaryName);
527
528  if (!LookupName(Result, getCurScope())) {
529    // If we don't find anything, return null; the AsmParser will assume
530    // it is a label of some sort.
531    return 0;
532  }
533
534  if (!Result.isSingleResult()) {
535    // FIXME: Diagnose result.
536    return 0;
537  }
538
539  NamedDecl *FoundDecl = Result.getFoundDecl();
540  if (isa<FunctionDecl>(FoundDecl))
541    return FoundDecl;
542  if (VarDecl *Var = dyn_cast<VarDecl>(FoundDecl)) {
543    QualType Ty = Var->getType();
544    Info.Type = Info.Size = Context.getTypeSizeInChars(Ty).getQuantity();
545    if (Ty->isArrayType()) {
546      const ArrayType *ATy = Context.getAsArrayType(Ty);
547      Info.Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity();
548      Info.Length = Info.Size / Info.Type;
549    }
550    Info.IsVarDecl = true;
551    return FoundDecl;
552  }
553
554  // FIXME: Handle other kinds of results? (FieldDecl, etc.)
555  // FIXME: Diagnose if we find something we can't handle, like a typedef.
556  return 0;
557}
558
559bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
560                                unsigned &Offset, SourceLocation AsmLoc) {
561  Offset = 0;
562  LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
563                          LookupOrdinaryName);
564
565  if (!LookupName(BaseResult, getCurScope()))
566    return true;
567
568  if (!BaseResult.isSingleResult())
569    return true;
570
571  const RecordType *RT = 0;
572  NamedDecl *FoundDecl = BaseResult.getFoundDecl();
573  if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl))
574    RT = VD->getType()->getAs<RecordType>();
575  else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(FoundDecl))
576    RT = TD->getUnderlyingType()->getAs<RecordType>();
577  if (!RT)
578    return true;
579
580  if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0))
581    return true;
582
583  LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(),
584                           LookupMemberName);
585
586  if (!LookupQualifiedName(FieldResult, RT->getDecl()))
587    return true;
588
589  // FIXME: Handle IndirectFieldDecl?
590  FieldDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
591  if (!FD)
592    return true;
593
594  const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
595  unsigned i = FD->getFieldIndex();
596  CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
597  Offset = (unsigned)Result.getQuantity();
598
599  return false;
600}
601
602StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
603                                ArrayRef<Token> AsmToks,SourceLocation EndLoc) {
604  SmallVector<IdentifierInfo*, 4> Names;
605  SmallVector<StringRef, 4> ConstraintRefs;
606  SmallVector<Expr*, 4> Exprs;
607  SmallVector<StringRef, 4> ClobberRefs;
608
609  llvm::Triple TheTriple = Context.getTargetInfo().getTriple();
610  llvm::Triple::ArchType ArchTy = TheTriple.getArch();
611  bool UnsupportedArch = ArchTy != llvm::Triple::x86 &&
612    ArchTy != llvm::Triple::x86_64;
613  if (UnsupportedArch)
614    Diag(AsmLoc, diag::err_msasm_unsupported_arch) << TheTriple.getArchName();
615
616  // Empty asm statements don't need to instantiate the AsmParser, etc.
617  if (UnsupportedArch || AsmToks.empty()) {
618    StringRef EmptyAsmStr;
619    MSAsmStmt *NS =
620      new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, /*IsSimple*/ true,
621                              /*IsVolatile*/ true, AsmToks, /*NumOutputs*/ 0,
622                              /*NumInputs*/ 0, Names, ConstraintRefs, Exprs,
623                              EmptyAsmStr, ClobberRefs, EndLoc);
624    return Owned(NS);
625  }
626
627  std::string AsmString;
628  SmallVector<unsigned, 8> TokOffsets;
629  if (buildMSAsmString(*this, AsmLoc, AsmToks, TokOffsets, AsmString))
630    return StmtError();
631
632  // Get the target specific parser.
633  std::string Error;
634  const std::string &TT = TheTriple.getTriple();
635  const llvm::Target *TheTarget(llvm::TargetRegistry::lookupTarget(TT, Error));
636
637  OwningPtr<llvm::MCAsmInfo> MAI(TheTarget->createMCAsmInfo(TT));
638  OwningPtr<llvm::MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TT));
639  OwningPtr<llvm::MCObjectFileInfo> MOFI(new llvm::MCObjectFileInfo());
640  OwningPtr<llvm::MCSubtargetInfo>
641    STI(TheTarget->createMCSubtargetInfo(TT, "", ""));
642
643  llvm::SourceMgr SrcMgr;
644  llvm::MCContext Ctx(*MAI, *MRI, MOFI.get(), &SrcMgr);
645  llvm::MemoryBuffer *Buffer =
646    llvm::MemoryBuffer::getMemBuffer(AsmString, "<MS inline asm>");
647
648  // Tell SrcMgr about this buffer, which is what the parser will pick up.
649  SrcMgr.AddNewSourceBuffer(Buffer, llvm::SMLoc());
650
651  OwningPtr<llvm::MCStreamer> Str(createNullStreamer(Ctx));
652  OwningPtr<llvm::MCAsmParser>
653    Parser(createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
654  OwningPtr<llvm::MCTargetAsmParser>
655    TargetParser(TheTarget->createMCAsmParser(*STI, *Parser));
656
657  // Get the instruction descriptor.
658  const llvm::MCInstrInfo *MII = TheTarget->createMCInstrInfo();
659  llvm::MCInstPrinter *IP =
660    TheTarget->createMCInstPrinter(1, *MAI, *MII, *MRI, *STI);
661
662  // Change to the Intel dialect.
663  Parser->setAssemblerDialect(1);
664  Parser->setTargetParser(*TargetParser.get());
665  Parser->setParsingInlineAsm(true);
666  TargetParser->setParsingInlineAsm(true);
667
668  MCAsmParserSemaCallbackImpl MCAPSI(*this, AsmLoc, AsmToks, TokOffsets);
669  TargetParser->setSemaCallback(&MCAPSI);
670  SrcMgr.setDiagHandler(MCAsmParserSemaCallbackImpl::MSAsmDiagHandlerCallback,
671                        &MCAPSI);
672
673  unsigned NumOutputs;
674  unsigned NumInputs;
675  std::string AsmStringIR;
676  SmallVector<std::pair<void *, bool>, 4> OpDecls;
677  SmallVector<std::string, 4> Constraints;
678  SmallVector<std::string, 4> Clobbers;
679  if (Parser->parseMSInlineAsm(AsmLoc.getPtrEncoding(), AsmStringIR,
680                               NumOutputs, NumInputs, OpDecls, Constraints,
681                               Clobbers, MII, IP, MCAPSI))
682    return StmtError();
683
684  // Build the vector of clobber StringRefs.
685  unsigned NumClobbers = Clobbers.size();
686  ClobberRefs.resize(NumClobbers);
687  for (unsigned i = 0; i != NumClobbers; ++i)
688    ClobberRefs[i] = StringRef(Clobbers[i]);
689
690  // Recast the void pointers and build the vector of constraint StringRefs.
691  unsigned NumExprs = NumOutputs + NumInputs;
692  Names.resize(NumExprs);
693  ConstraintRefs.resize(NumExprs);
694  Exprs.resize(NumExprs);
695  for (unsigned i = 0, e = NumExprs; i != e; ++i) {
696    NamedDecl *OpDecl = static_cast<NamedDecl *>(OpDecls[i].first);
697    if (!OpDecl)
698      return StmtError();
699
700    DeclarationNameInfo NameInfo(OpDecl->getDeclName(), AsmLoc);
701    ExprResult OpExpr = BuildDeclarationNameExpr(CXXScopeSpec(), NameInfo,
702                                                 OpDecl);
703    if (OpExpr.isInvalid())
704      return StmtError();
705
706    // Need address of variable.
707    if (OpDecls[i].second)
708      OpExpr = BuildUnaryOp(getCurScope(), AsmLoc, clang::UO_AddrOf,
709                            OpExpr.take());
710
711    Names[i] = OpDecl->getIdentifier();
712    ConstraintRefs[i] = StringRef(Constraints[i]);
713    Exprs[i] = OpExpr.take();
714  }
715
716  bool IsSimple = NumExprs > 0;
717  MSAsmStmt *NS =
718    new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
719                            /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
720                            Names, ConstraintRefs, Exprs, AsmStringIR,
721                            ClobberRefs, EndLoc);
722  return Owned(NS);
723}
724