clang/lib/Sema/SemaStmtAsm.cpp

   1 //===--- SemaStmtAsm.cpp - Semantic Analysis for Asm Statements -----------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 //  This file implements semantic analysis for inline asm statements.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/AST/ExprCXX.h"
  14 #include "clang/AST/GlobalDecl.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 "clang/Sema/SemaInternal.h"
  24 #include "llvm/ADT/ArrayRef.h"
  25 #include "llvm/ADT/StringExtras.h"
  26 #include "llvm/ADT/StringSet.h"
  27 #include "llvm/MC/MCParser/MCAsmParser.h"
  28 #include <optional>
  29 using namespace clang;
  30 using namespace sema;
  31
  32 /// Remove the upper-level LValueToRValue cast from an expression.
  33 static void removeLValueToRValueCast(Expr *E) {
  34   Expr *Parent = E;
  35   Expr *ExprUnderCast = nullptr;
  36   SmallVector<Expr *, 8> ParentsToUpdate;
  37
  38   while (true) {
  39     ParentsToUpdate.push_back(Parent);
  40     if (auto *ParenE = dyn_cast<ParenExpr>(Parent)) {
  41       Parent = ParenE->getSubExpr();
  42       continue;
  43     }
  44
  45     Expr *Child = nullptr;
  46     CastExpr *ParentCast = dyn_cast<CastExpr>(Parent);
  47     if (ParentCast)
  48       Child = ParentCast->getSubExpr();
  49     else
  50       return;
  51
  52     if (auto *CastE = dyn_cast<CastExpr>(Child))
  53       if (CastE->getCastKind() == CK_LValueToRValue) {
  54         ExprUnderCast = CastE->getSubExpr();
  55         // LValueToRValue cast inside GCCAsmStmt requires an explicit cast.
  56         ParentCast->setSubExpr(ExprUnderCast);
  57         break;
  58       }
  59     Parent = Child;
  60   }
  61
  62   // Update parent expressions to have same ValueType as the underlying.
  63   assert(ExprUnderCast &&
  64          "Should be reachable only if LValueToRValue cast was found!");
  65   auto ValueKind = ExprUnderCast->getValueKind();
  66   for (Expr *E : ParentsToUpdate)
  67     E->setValueKind(ValueKind);
  68 }
  69
  70 /// Emit a warning about usage of "noop"-like casts for lvalues (GNU extension)
  71 /// and fix the argument with removing LValueToRValue cast from the expression.
  72 static void emitAndFixInvalidAsmCastLValue(const Expr *LVal, Expr *BadArgument,
  73                                            Sema &S) {
  74   if (!S.getLangOpts().HeinousExtensions) {
  75     S.Diag(LVal->getBeginLoc(), diag::err_invalid_asm_cast_lvalue)
  76         << BadArgument->getSourceRange();
  77   } else {
  78     S.Diag(LVal->getBeginLoc(), diag::warn_invalid_asm_cast_lvalue)
  79         << BadArgument->getSourceRange();
  80   }
  81   removeLValueToRValueCast(BadArgument);
  82 }
  83
  84 /// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
  85 /// ignore "noop" casts in places where an lvalue is required by an inline asm.
  86 /// We emulate this behavior when -fheinous-gnu-extensions is specified, but
  87 /// provide a strong guidance to not use it.
  88 ///
  89 /// This method checks to see if the argument is an acceptable l-value and
  90 /// returns false if it is a case we can handle.
  91 static bool CheckAsmLValue(Expr *E, Sema &S) {
  92   // Type dependent expressions will be checked during instantiation.
  93   if (E->isTypeDependent())
  94     return false;
  95
  96   if (E->isLValue())
  97     return false;  // Cool, this is an lvalue.
  98
  99   // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
 100   // are supposed to allow.
 101   const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
 102   if (E != E2 && E2->isLValue()) {
 103     emitAndFixInvalidAsmCastLValue(E2, E, S);
 104     // Accept, even if we emitted an error diagnostic.
 105     return false;
 106   }
 107
 108   // None of the above, just randomly invalid non-lvalue.
 109   return true;
 110 }
 111
 112 /// isOperandMentioned - Return true if the specified operand # is mentioned
 113 /// anywhere in the decomposed asm string.
 114 static bool
 115 isOperandMentioned(unsigned OpNo,
 116                    ArrayRef<GCCAsmStmt::AsmStringPiece> AsmStrPieces) {
 117   for (unsigned p = 0, e = AsmStrPieces.size(); p != e; ++p) {
 118     const GCCAsmStmt::AsmStringPiece &Piece = AsmStrPieces[p];
 119     if (!Piece.isOperand())
 120       continue;
 121
 122     // If this is a reference to the input and if the input was the smaller
 123     // one, then we have to reject this asm.
 124     if (Piece.getOperandNo() == OpNo)
 125       return true;
 126   }
 127   return false;
 128 }
 129
 130 static bool CheckNakedParmReference(Expr *E, Sema &S) {
 131   FunctionDecl *Func = dyn_cast<FunctionDecl>(S.CurContext);
 132   if (!Func)
 133     return false;
 134   if (!Func->hasAttr<NakedAttr>())
 135     return false;
 136
 137   SmallVector<Expr*, 4> WorkList;
 138   WorkList.push_back(E);
 139   while (WorkList.size()) {
 140     Expr *E = WorkList.pop_back_val();
 141     if (isa<CXXThisExpr>(E)) {
 142       S.Diag(E->getBeginLoc(), diag::err_asm_naked_this_ref);
 143       S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
 144       return true;
 145     }
 146     if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
 147       if (isa<ParmVarDecl>(DRE->getDecl())) {
 148         S.Diag(DRE->getBeginLoc(), diag::err_asm_naked_parm_ref);
 149         S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
 150         return true;
 151       }
 152     }
 153     for (Stmt *Child : E->children()) {
 154       if (Expr *E = dyn_cast_or_null<Expr>(Child))
 155         WorkList.push_back(E);
 156     }
 157   }
 158   return false;
 159 }
 160
 161 /// Returns true if given expression is not compatible with inline
 162 /// assembly's memory constraint; false otherwise.
 163 static bool checkExprMemoryConstraintCompat(Sema &S, Expr *E,
 164                                             TargetInfo::ConstraintInfo &Info,
 165                                             bool is_input_expr) {
 166   enum {
 167     ExprBitfield = 0,
 168     ExprVectorElt,
 169     ExprGlobalRegVar,
 170     ExprSafeType
 171   } EType = ExprSafeType;
 172
 173   // Bitfields, vector elements and global register variables are not
 174   // compatible.
 175   if (E->refersToBitField())
 176     EType = ExprBitfield;
 177   else if (E->refersToVectorElement())
 178     EType = ExprVectorElt;
 179   else if (E->refersToGlobalRegisterVar())
 180     EType = ExprGlobalRegVar;
 181
 182   if (EType != ExprSafeType) {
 183     S.Diag(E->getBeginLoc(), diag::err_asm_non_addr_value_in_memory_constraint)
 184         << EType << is_input_expr << Info.getConstraintStr()
 185         << E->getSourceRange();
 186     return true;
 187   }
 188
 189   return false;
 190 }
 191
 192 // Extracting the register name from the Expression value,
 193 // if there is no register name to extract, returns ""
 194 static StringRef extractRegisterName(const Expr *Expression,
 195                                      const TargetInfo &Target) {
 196   Expression = Expression->IgnoreImpCasts();
 197   if (const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(Expression)) {
 198     // Handle cases where the expression is a variable
 199     const VarDecl *Variable = dyn_cast<VarDecl>(AsmDeclRef->getDecl());
 200     if (Variable && Variable->getStorageClass() == SC_Register) {
 201       if (AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>())
 202         if (Target.isValidGCCRegisterName(Attr->getLabel()))
 203           return Target.getNormalizedGCCRegisterName(Attr->getLabel(), true);
 204     }
 205   }
 206   return "";
 207 }
 208
 209 // Checks if there is a conflict between the input and output lists with the
 210 // clobbers list. If there's a conflict, returns the location of the
 211 // conflicted clobber, else returns nullptr
 212 static SourceLocation
 213 getClobberConflictLocation(MultiExprArg Exprs, StringLiteral **Constraints,
 214                            StringLiteral **Clobbers, int NumClobbers,
 215                            unsigned NumLabels,
 216                            const TargetInfo &Target, ASTContext &Cont) {
 217   llvm::StringSet<> InOutVars;
 218   // Collect all the input and output registers from the extended asm
 219   // statement in order to check for conflicts with the clobber list
 220   for (unsigned int i = 0; i < Exprs.size() - NumLabels; ++i) {
 221     StringRef Constraint = Constraints[i]->getString();
 222     StringRef InOutReg = Target.getConstraintRegister(
 223         Constraint, extractRegisterName(Exprs[i], Target));
 224     if (InOutReg != "")
 225       InOutVars.insert(InOutReg);
 226   }
 227   // Check for each item in the clobber list if it conflicts with the input
 228   // or output
 229   for (int i = 0; i < NumClobbers; ++i) {
 230     StringRef Clobber = Clobbers[i]->getString();
 231     // We only check registers, therefore we don't check cc and memory
 232     // clobbers
 233     if (Clobber == "cc" || Clobber == "memory" || Clobber == "unwind")
 234       continue;
 235     Clobber = Target.getNormalizedGCCRegisterName(Clobber, true);
 236     // Go over the output's registers we collected
 237     if (InOutVars.count(Clobber))
 238       return Clobbers[i]->getBeginLoc();
 239   }
 240   return SourceLocation();
 241 }
 242
 243 StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
 244                                  bool IsVolatile, unsigned NumOutputs,
 245                                  unsigned NumInputs, IdentifierInfo **Names,
 246                                  MultiExprArg constraints, MultiExprArg Exprs,
 247                                  Expr *asmString, MultiExprArg clobbers,
 248                                  unsigned NumLabels,
 249                                  SourceLocation RParenLoc) {
 250   unsigned NumClobbers = clobbers.size();
 251   StringLiteral **Constraints =
 252     reinterpret_cast<StringLiteral**>(constraints.data());
 253   StringLiteral *AsmString = cast<StringLiteral>(asmString);
 254   StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.data());
 255
 256   SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
 257
 258   // The parser verifies that there is a string literal here.
 259   assert(AsmString->isOrdinary());
 260
 261   FunctionDecl *FD = dyn_cast<FunctionDecl>(getCurLexicalContext());
 262   llvm::StringMap<bool> FeatureMap;
 263   Context.getFunctionFeatureMap(FeatureMap, FD);
 264
 265   for (unsigned i = 0; i != NumOutputs; i++) {
 266     StringLiteral *Literal = Constraints[i];
 267     assert(Literal->isOrdinary());
 268
 269     StringRef OutputName;
 270     if (Names[i])
 271       OutputName = Names[i]->getName();
 272
 273     TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
 274     if (!Context.getTargetInfo().validateOutputConstraint(Info) &&
 275         !(LangOpts.HIPStdPar && LangOpts.CUDAIsDevice)) {
 276       targetDiag(Literal->getBeginLoc(),
 277                  diag::err_asm_invalid_output_constraint)
 278           << Info.getConstraintStr();
 279       return new (Context)
 280           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
 281                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
 282                      NumClobbers, Clobbers, NumLabels, RParenLoc);
 283     }
 284
 285     ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
 286     if (ER.isInvalid())
 287       return StmtError();
 288     Exprs[i] = ER.get();
 289
 290     // Check that the output exprs are valid lvalues.
 291     Expr *OutputExpr = Exprs[i];
 292
 293     // Referring to parameters is not allowed in naked functions.
 294     if (CheckNakedParmReference(OutputExpr, *this))
 295       return StmtError();
 296
 297     // Check that the output expression is compatible with memory constraint.
 298     if (Info.allowsMemory() &&
 299         checkExprMemoryConstraintCompat(*this, OutputExpr, Info, false))
 300       return StmtError();
 301
 302     // Disallow bit-precise integer types, since the backends tend to have
 303     // difficulties with abnormal sizes.
 304     if (OutputExpr->getType()->isBitIntType())
 305       return StmtError(
 306           Diag(OutputExpr->getBeginLoc(), diag::err_asm_invalid_type)
 307           << OutputExpr->getType() << 0 /*Input*/
 308           << OutputExpr->getSourceRange());
 309
 310     OutputConstraintInfos.push_back(Info);
 311
 312     // If this is dependent, just continue.
 313     if (OutputExpr->isTypeDependent())
 314       continue;
 315
 316     Expr::isModifiableLvalueResult IsLV =
 317         OutputExpr->isModifiableLvalue(Context, /*Loc=*/nullptr);
 318     switch (IsLV) {
 319     case Expr::MLV_Valid:
 320       // Cool, this is an lvalue.
 321       break;
 322     case Expr::MLV_ArrayType:
 323       // This is OK too.
 324       break;
 325     case Expr::MLV_LValueCast: {
 326       const Expr *LVal = OutputExpr->IgnoreParenNoopCasts(Context);
 327       emitAndFixInvalidAsmCastLValue(LVal, OutputExpr, *this);
 328       // Accept, even if we emitted an error diagnostic.
 329       break;
 330     }
 331     case Expr::MLV_IncompleteType:
 332     case Expr::MLV_IncompleteVoidType:
 333       if (RequireCompleteType(OutputExpr->getBeginLoc(), Exprs[i]->getType(),
 334                               diag::err_dereference_incomplete_type))
 335         return StmtError();
 336       [[fallthrough]];
 337     default:
 338       return StmtError(Diag(OutputExpr->getBeginLoc(),
 339                             diag::err_asm_invalid_lvalue_in_output)
 340                        << OutputExpr->getSourceRange());
 341     }
 342
 343     unsigned Size = Context.getTypeSize(OutputExpr->getType());
 344     if (!Context.getTargetInfo().validateOutputSize(
 345             FeatureMap, Literal->getString(), Size)) {
 346       targetDiag(OutputExpr->getBeginLoc(), diag::err_asm_invalid_output_size)
 347           << Info.getConstraintStr();
 348       return new (Context)
 349           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
 350                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
 351                      NumClobbers, Clobbers, NumLabels, RParenLoc);
 352     }
 353   }
 354
 355   SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
 356
 357   for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
 358     StringLiteral *Literal = Constraints[i];
 359     assert(Literal->isOrdinary());
 360
 361     StringRef InputName;
 362     if (Names[i])
 363       InputName = Names[i]->getName();
 364
 365     TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
 366     if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos,
 367                                                          Info)) {
 368       targetDiag(Literal->getBeginLoc(), diag::err_asm_invalid_input_constraint)
 369           << Info.getConstraintStr();
 370       return new (Context)
 371           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
 372                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
 373                      NumClobbers, Clobbers, NumLabels, RParenLoc);
 374     }
 375
 376     ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
 377     if (ER.isInvalid())
 378       return StmtError();
 379     Exprs[i] = ER.get();
 380
 381     Expr *InputExpr = Exprs[i];
 382
 383     if (InputExpr->getType()->isMemberPointerType())
 384       return StmtError(Diag(InputExpr->getBeginLoc(),
 385                             diag::err_asm_pmf_through_constraint_not_permitted)
 386                        << InputExpr->getSourceRange());
 387
 388     // Referring to parameters is not allowed in naked functions.
 389     if (CheckNakedParmReference(InputExpr, *this))
 390       return StmtError();
 391
 392     // Check that the input expression is compatible with memory constraint.
 393     if (Info.allowsMemory() &&
 394         checkExprMemoryConstraintCompat(*this, InputExpr, Info, true))
 395       return StmtError();
 396
 397     // Only allow void types for memory constraints.
 398     if (Info.allowsMemory() && !Info.allowsRegister()) {
 399       if (CheckAsmLValue(InputExpr, *this))
 400         return StmtError(Diag(InputExpr->getBeginLoc(),
 401                               diag::err_asm_invalid_lvalue_in_input)
 402                          << Info.getConstraintStr()
 403                          << InputExpr->getSourceRange());
 404     } else {
 405       ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
 406       if (Result.isInvalid())
 407         return StmtError();
 408
 409       InputExpr = Exprs[i] = Result.get();
 410
 411       if (Info.requiresImmediateConstant() && !Info.allowsRegister()) {
 412         if (!InputExpr->isValueDependent()) {
 413           Expr::EvalResult EVResult;
 414           if (InputExpr->EvaluateAsRValue(EVResult, Context, true)) {
 415             // For compatibility with GCC, we also allow pointers that would be
 416             // integral constant expressions if they were cast to int.
 417             llvm::APSInt IntResult;
 418             if (EVResult.Val.toIntegralConstant(IntResult, InputExpr->getType(),
 419                                                 Context))
 420               if (!Info.isValidAsmImmediate(IntResult))
 421                 return StmtError(
 422                     Diag(InputExpr->getBeginLoc(),
 423                          diag::err_invalid_asm_value_for_constraint)
 424                     << toString(IntResult, 10) << Info.getConstraintStr()
 425                     << InputExpr->getSourceRange());
 426           }
 427         }
 428       }
 429     }
 430
 431     if (Info.allowsRegister()) {
 432       if (InputExpr->getType()->isVoidType()) {
 433         return StmtError(
 434             Diag(InputExpr->getBeginLoc(), diag::err_asm_invalid_type_in_input)
 435             << InputExpr->getType() << Info.getConstraintStr()
 436             << InputExpr->getSourceRange());
 437       }
 438     }
 439
 440     if (InputExpr->getType()->isBitIntType())
 441       return StmtError(
 442           Diag(InputExpr->getBeginLoc(), diag::err_asm_invalid_type)
 443           << InputExpr->getType() << 1 /*Output*/
 444           << InputExpr->getSourceRange());
 445
 446     InputConstraintInfos.push_back(Info);
 447
 448     const Type *Ty = Exprs[i]->getType().getTypePtr();
 449     if (Ty->isDependentType())
 450       continue;
 451
 452     if (!Ty->isVoidType() || !Info.allowsMemory())
 453       if (RequireCompleteType(InputExpr->getBeginLoc(), Exprs[i]->getType(),
 454                               diag::err_dereference_incomplete_type))
 455         return StmtError();
 456
 457     unsigned Size = Context.getTypeSize(Ty);
 458     if (!Context.getTargetInfo().validateInputSize(FeatureMap,
 459                                                    Literal->getString(), Size))
 460       return targetDiag(InputExpr->getBeginLoc(),
 461                         diag::err_asm_invalid_input_size)
 462              << Info.getConstraintStr();
 463   }
 464
 465   std::optional<SourceLocation> UnwindClobberLoc;
 466
 467   // Check that the clobbers are valid.
 468   for (unsigned i = 0; i != NumClobbers; i++) {
 469     StringLiteral *Literal = Clobbers[i];
 470     assert(Literal->isOrdinary());
 471
 472     StringRef Clobber = Literal->getString();
 473
 474     if (!Context.getTargetInfo().isValidClobber(Clobber)) {
 475       targetDiag(Literal->getBeginLoc(), diag::err_asm_unknown_register_name)
 476           << Clobber;
 477       return new (Context)
 478           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
 479                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
 480                      NumClobbers, Clobbers, NumLabels, RParenLoc);
 481     }
 482
 483     if (Clobber == "unwind") {
 484       UnwindClobberLoc = Literal->getBeginLoc();
 485     }
 486   }
 487
 488   // Using unwind clobber and asm-goto together is not supported right now.
 489   if (UnwindClobberLoc && NumLabels > 0) {
 490     targetDiag(*UnwindClobberLoc, diag::err_asm_unwind_and_goto);
 491     return new (Context)
 492         GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs,
 493                    Names, Constraints, Exprs.data(), AsmString, NumClobbers,
 494                    Clobbers, NumLabels, RParenLoc);
 495   }
 496
 497   GCCAsmStmt *NS =
 498     new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
 499                              NumInputs, Names, Constraints, Exprs.data(),
 500                              AsmString, NumClobbers, Clobbers, NumLabels,
 501                              RParenLoc);
 502   // Validate the asm string, ensuring it makes sense given the operands we
 503   // have.
 504   SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
 505   unsigned DiagOffs;
 506   if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
 507     targetDiag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
 508         << AsmString->getSourceRange();
 509     return NS;
 510   }
 511
 512   // Validate constraints and modifiers.
 513   for (unsigned i = 0, e = Pieces.size(); i != e; ++i) {
 514     GCCAsmStmt::AsmStringPiece &Piece = Pieces[i];
 515     if (!Piece.isOperand()) continue;
 516
 517     // Look for the correct constraint index.
 518     unsigned ConstraintIdx = Piece.getOperandNo();
 519     unsigned NumOperands = NS->getNumOutputs() + NS->getNumInputs();
 520     // Labels are the last in the Exprs list.
 521     if (NS->isAsmGoto() && ConstraintIdx >= NumOperands)
 522       continue;
 523     // Look for the (ConstraintIdx - NumOperands + 1)th constraint with
 524     // modifier '+'.
 525     if (ConstraintIdx >= NumOperands) {
 526       unsigned I = 0, E = NS->getNumOutputs();
 527
 528       for (unsigned Cnt = ConstraintIdx - NumOperands; I != E; ++I)
 529         if (OutputConstraintInfos[I].isReadWrite() && Cnt-- == 0) {
 530           ConstraintIdx = I;
 531           break;
 532         }
 533
 534       assert(I != E && "Invalid operand number should have been caught in "
 535                        " AnalyzeAsmString");
 536     }
 537
 538     // Now that we have the right indexes go ahead and check.
 539     StringLiteral *Literal = Constraints[ConstraintIdx];
 540     const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr();
 541     if (Ty->isDependentType() || Ty->isIncompleteType())
 542       continue;
 543
 544     unsigned Size = Context.getTypeSize(Ty);
 545     std::string SuggestedModifier;
 546     if (!Context.getTargetInfo().validateConstraintModifier(
 547             Literal->getString(), Piece.getModifier(), Size,
 548             SuggestedModifier)) {
 549       targetDiag(Exprs[ConstraintIdx]->getBeginLoc(),
 550                  diag::warn_asm_mismatched_size_modifier);
 551
 552       if (!SuggestedModifier.empty()) {
 553         auto B = targetDiag(Piece.getRange().getBegin(),
 554                             diag::note_asm_missing_constraint_modifier)
 555                  << SuggestedModifier;
 556         SuggestedModifier = "%" + SuggestedModifier + Piece.getString();
 557         B << FixItHint::CreateReplacement(Piece.getRange(), SuggestedModifier);
 558       }
 559     }
 560   }
 561
 562   // Validate tied input operands for type mismatches.
 563   unsigned NumAlternatives = ~0U;
 564   for (unsigned i = 0, e = OutputConstraintInfos.size(); i != e; ++i) {
 565     TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
 566     StringRef ConstraintStr = Info.getConstraintStr();
 567     unsigned AltCount = ConstraintStr.count(',') + 1;
 568     if (NumAlternatives == ~0U) {
 569       NumAlternatives = AltCount;
 570     } else if (NumAlternatives != AltCount) {
 571       targetDiag(NS->getOutputExpr(i)->getBeginLoc(),
 572                  diag::err_asm_unexpected_constraint_alternatives)
 573           << NumAlternatives << AltCount;
 574       return NS;
 575     }
 576   }
 577   SmallVector<size_t, 4> InputMatchedToOutput(OutputConstraintInfos.size(),
 578                                               ~0U);
 579   for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
 580     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
 581     StringRef ConstraintStr = Info.getConstraintStr();
 582     unsigned AltCount = ConstraintStr.count(',') + 1;
 583     if (NumAlternatives == ~0U) {
 584       NumAlternatives = AltCount;
 585     } else if (NumAlternatives != AltCount) {
 586       targetDiag(NS->getInputExpr(i)->getBeginLoc(),
 587                  diag::err_asm_unexpected_constraint_alternatives)
 588           << NumAlternatives << AltCount;
 589       return NS;
 590     }
 591
 592     // If this is a tied constraint, verify that the output and input have
 593     // either exactly the same type, or that they are int/ptr operands with the
 594     // same size (int/long, int*/long, are ok etc).
 595     if (!Info.hasTiedOperand()) continue;
 596
 597     unsigned TiedTo = Info.getTiedOperand();
 598     unsigned InputOpNo = i+NumOutputs;
 599     Expr *OutputExpr = Exprs[TiedTo];
 600     Expr *InputExpr = Exprs[InputOpNo];
 601
 602     // Make sure no more than one input constraint matches each output.
 603     assert(TiedTo < InputMatchedToOutput.size() && "TiedTo value out of range");
 604     if (InputMatchedToOutput[TiedTo] != ~0U) {
 605       targetDiag(NS->getInputExpr(i)->getBeginLoc(),
 606                  diag::err_asm_input_duplicate_match)
 607           << TiedTo;
 608       targetDiag(NS->getInputExpr(InputMatchedToOutput[TiedTo])->getBeginLoc(),
 609                  diag::note_asm_input_duplicate_first)
 610           << TiedTo;
 611       return NS;
 612     }
 613     InputMatchedToOutput[TiedTo] = i;
 614
 615     if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
 616       continue;
 617
 618     QualType InTy = InputExpr->getType();
 619     QualType OutTy = OutputExpr->getType();
 620     if (Context.hasSameType(InTy, OutTy))
 621       continue;  // All types can be tied to themselves.
 622
 623     // Decide if the input and output are in the same domain (integer/ptr or
 624     // floating point.
 625     enum AsmDomain {
 626       AD_Int, AD_FP, AD_Other
 627     } InputDomain, OutputDomain;
 628
 629     if (InTy->isIntegerType() || InTy->isPointerType())
 630       InputDomain = AD_Int;
 631     else if (InTy->isRealFloatingType())
 632       InputDomain = AD_FP;
 633     else
 634       InputDomain = AD_Other;
 635
 636     if (OutTy->isIntegerType() || OutTy->isPointerType())
 637       OutputDomain = AD_Int;
 638     else if (OutTy->isRealFloatingType())
 639       OutputDomain = AD_FP;
 640     else
 641       OutputDomain = AD_Other;
 642
 643     // They are ok if they are the same size and in the same domain.  This
 644     // allows tying things like:
 645     //   void* to int*
 646     //   void* to int            if they are the same size.
 647     //   double to long double   if they are the same size.
 648     //
 649     uint64_t OutSize = Context.getTypeSize(OutTy);
 650     uint64_t InSize = Context.getTypeSize(InTy);
 651     if (OutSize == InSize && InputDomain == OutputDomain &&
 652         InputDomain != AD_Other)
 653       continue;
 654
 655     // If the smaller input/output operand is not mentioned in the asm string,
 656     // then we can promote the smaller one to a larger input and the asm string
 657     // won't notice.
 658     bool SmallerValueMentioned = false;
 659
 660     // If this is a reference to the input and if the input was the smaller
 661     // one, then we have to reject this asm.
 662     if (isOperandMentioned(InputOpNo, Pieces)) {
 663       // This is a use in the asm string of the smaller operand.  Since we
 664       // codegen this by promoting to a wider value, the asm will get printed
 665       // "wrong".
 666       SmallerValueMentioned |= InSize < OutSize;
 667     }
 668     if (isOperandMentioned(TiedTo, Pieces)) {
 669       // If this is a reference to the output, and if the output is the larger
 670       // value, then it's ok because we'll promote the input to the larger type.
 671       SmallerValueMentioned |= OutSize < InSize;
 672     }
 673
 674     // If the smaller value wasn't mentioned in the asm string, and if the
 675     // output was a register, just extend the shorter one to the size of the
 676     // larger one.
 677     if (!SmallerValueMentioned && InputDomain != AD_Other &&
 678         OutputConstraintInfos[TiedTo].allowsRegister()) {
 679       // FIXME: GCC supports the OutSize to be 128 at maximum. Currently codegen
 680       // crash when the size larger than the register size. So we limit it here.
 681       if (OutTy->isStructureType() &&
 682           Context.getIntTypeForBitwidth(OutSize, /*Signed*/ false).isNull()) {
 683         targetDiag(OutputExpr->getExprLoc(), diag::err_store_value_to_reg);
 684         return NS;
 685       }
 686
 687       continue;
 688     }
 689
 690     // Either both of the operands were mentioned or the smaller one was
 691     // mentioned.  One more special case that we'll allow: if the tied input is
 692     // integer, unmentioned, and is a constant, then we'll allow truncating it
 693     // down to the size of the destination.
 694     if (InputDomain == AD_Int && OutputDomain == AD_Int &&
 695         !isOperandMentioned(InputOpNo, Pieces) &&
 696         InputExpr->isEvaluatable(Context)) {
 697       CastKind castKind =
 698         (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast);
 699       InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).get();
 700       Exprs[InputOpNo] = InputExpr;
 701       NS->setInputExpr(i, InputExpr);
 702       continue;
 703     }
 704
 705     targetDiag(InputExpr->getBeginLoc(), diag::err_asm_tying_incompatible_types)
 706         << InTy << OutTy << OutputExpr->getSourceRange()
 707         << InputExpr->getSourceRange();
 708     return NS;
 709   }
 710
 711   // Check for conflicts between clobber list and input or output lists
 712   SourceLocation ConstraintLoc =
 713       getClobberConflictLocation(Exprs, Constraints, Clobbers, NumClobbers,
 714                                  NumLabels,
 715                                  Context.getTargetInfo(), Context);
 716   if (ConstraintLoc.isValid())
 717     targetDiag(ConstraintLoc, diag::error_inoutput_conflict_with_clobber);
 718
 719   // Check for duplicate asm operand name between input, output and label lists.
 720   typedef std::pair<StringRef , Expr *> NamedOperand;
 721   SmallVector<NamedOperand, 4> NamedOperandList;
 722   for (unsigned i = 0, e = NumOutputs + NumInputs + NumLabels; i != e; ++i)
 723     if (Names[i])
 724       NamedOperandList.emplace_back(
 725           std::make_pair(Names[i]->getName(), Exprs[i]));
 726   // Sort NamedOperandList.
 727   llvm::stable_sort(NamedOperandList, llvm::less_first());
 728   // Find adjacent duplicate operand.
 729   SmallVector<NamedOperand, 4>::iterator Found =
 730       std::adjacent_find(begin(NamedOperandList), end(NamedOperandList),
 731                          [](const NamedOperand &LHS, const NamedOperand &RHS) {
 732                            return LHS.first == RHS.first;
 733                          });
 734   if (Found != NamedOperandList.end()) {
 735     Diag((Found + 1)->second->getBeginLoc(),
 736          diag::error_duplicate_asm_operand_name)
 737         << (Found + 1)->first;
 738     Diag(Found->second->getBeginLoc(), diag::note_duplicate_asm_operand_name)
 739         << Found->first;
 740     return StmtError();
 741   }
 742   if (NS->isAsmGoto())
 743     setFunctionHasBranchIntoScope();
 744
 745   CleanupVarDeclMarking();
 746   DiscardCleanupsInEvaluationContext();
 747   return NS;
 748 }
 749
 750 void Sema::FillInlineAsmIdentifierInfo(Expr *Res,
 751                                        llvm::InlineAsmIdentifierInfo &Info) {
 752   QualType T = Res->getType();
 753   Expr::EvalResult Eval;
 754   if (T->isFunctionType() || T->isDependentType())
 755     return Info.setLabel(Res);
 756   if (Res->isPRValue()) {
 757     bool IsEnum = isa<clang::EnumType>(T);
 758     if (DeclRefExpr *DRE = dyn_cast<clang::DeclRefExpr>(Res))
 759       if (DRE->getDecl()->getKind() == Decl::EnumConstant)
 760         IsEnum = true;
 761     if (IsEnum && Res->EvaluateAsRValue(Eval, Context))
 762       return Info.setEnum(Eval.Val.getInt().getSExtValue());
 763
 764     return Info.setLabel(Res);
 765   }
 766   unsigned Size = Context.getTypeSizeInChars(T).getQuantity();
 767   unsigned Type = Size;
 768   if (const auto *ATy = Context.getAsArrayType(T))
 769     Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity();
 770   bool IsGlobalLV = false;
 771   if (Res->EvaluateAsLValue(Eval, Context))
 772     IsGlobalLV = Eval.isGlobalLValue();
 773   Info.setVar(Res, IsGlobalLV, Size, Type);
 774 }
 775
 776 ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS,
 777                                            SourceLocation TemplateKWLoc,
 778                                            UnqualifiedId &Id,
 779                                            bool IsUnevaluatedContext) {
 780
 781   if (IsUnevaluatedContext)
 782     PushExpressionEvaluationContext(
 783         ExpressionEvaluationContext::UnevaluatedAbstract,
 784         ReuseLambdaContextDecl);
 785
 786   ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id,
 787                                         /*trailing lparen*/ false,
 788                                         /*is & operand*/ false,
 789                                         /*CorrectionCandidateCallback=*/nullptr,
 790                                         /*IsInlineAsmIdentifier=*/ true);
 791
 792   if (IsUnevaluatedContext)
 793     PopExpressionEvaluationContext();
 794
 795   if (!Result.isUsable()) return Result;
 796
 797   Result = CheckPlaceholderExpr(Result.get());
 798   if (!Result.isUsable()) return Result;
 799
 800   // Referring to parameters is not allowed in naked functions.
 801   if (CheckNakedParmReference(Result.get(), *this))
 802     return ExprError();
 803
 804   QualType T = Result.get()->getType();
 805
 806   if (T->isDependentType()) {
 807     return Result;
 808   }
 809
 810   // Any sort of function type is fine.
 811   if (T->isFunctionType()) {
 812     return Result;
 813   }
 814
 815   // Otherwise, it needs to be a complete type.
 816   if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) {
 817     return ExprError();
 818   }
 819
 820   return Result;
 821 }
 822
 823 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
 824                                 unsigned &Offset, SourceLocation AsmLoc) {
 825   Offset = 0;
 826   SmallVector<StringRef, 2> Members;
 827   Member.split(Members, ".");
 828
 829   NamedDecl *FoundDecl = nullptr;
 830
 831   // MS InlineAsm uses 'this' as a base
 832   if (getLangOpts().CPlusPlus && Base.equals("this")) {
 833     if (const Type *PT = getCurrentThisType().getTypePtrOrNull())
 834       FoundDecl = PT->getPointeeType()->getAsTagDecl();
 835   } else {
 836     LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
 837                             LookupOrdinaryName);
 838     if (LookupName(BaseResult, getCurScope()) && BaseResult.isSingleResult())
 839       FoundDecl = BaseResult.getFoundDecl();
 840   }
 841
 842   if (!FoundDecl)
 843     return true;
 844
 845   for (StringRef NextMember : Members) {
 846     const RecordType *RT = nullptr;
 847     if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl))
 848       RT = VD->getType()->getAs<RecordType>();
 849     else if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(FoundDecl)) {
 850       MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
 851       // MS InlineAsm often uses struct pointer aliases as a base
 852       QualType QT = TD->getUnderlyingType();
 853       if (const auto *PT = QT->getAs<PointerType>())
 854         QT = PT->getPointeeType();
 855       RT = QT->getAs<RecordType>();
 856     } else if (TypeDecl *TD = dyn_cast<TypeDecl>(FoundDecl))
 857       RT = TD->getTypeForDecl()->getAs<RecordType>();
 858     else if (FieldDecl *TD = dyn_cast<FieldDecl>(FoundDecl))
 859       RT = TD->getType()->getAs<RecordType>();
 860     if (!RT)
 861       return true;
 862
 863     if (RequireCompleteType(AsmLoc, QualType(RT, 0),
 864                             diag::err_asm_incomplete_type))
 865       return true;
 866
 867     LookupResult FieldResult(*this, &Context.Idents.get(NextMember),
 868                              SourceLocation(), LookupMemberName);
 869
 870     if (!LookupQualifiedName(FieldResult, RT->getDecl()))
 871       return true;
 872
 873     if (!FieldResult.isSingleResult())
 874       return true;
 875     FoundDecl = FieldResult.getFoundDecl();
 876
 877     // FIXME: Handle IndirectFieldDecl?
 878     FieldDecl *FD = dyn_cast<FieldDecl>(FoundDecl);
 879     if (!FD)
 880       return true;
 881
 882     const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
 883     unsigned i = FD->getFieldIndex();
 884     CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
 885     Offset += (unsigned)Result.getQuantity();
 886   }
 887
 888   return false;
 889 }
 890
 891 ExprResult
 892 Sema::LookupInlineAsmVarDeclField(Expr *E, StringRef Member,
 893                                   SourceLocation AsmLoc) {
 894
 895   QualType T = E->getType();
 896   if (T->isDependentType()) {
 897     DeclarationNameInfo NameInfo;
 898     NameInfo.setLoc(AsmLoc);
 899     NameInfo.setName(&Context.Idents.get(Member));
 900     return CXXDependentScopeMemberExpr::Create(
 901         Context, E, T, /*IsArrow=*/false, AsmLoc, NestedNameSpecifierLoc(),
 902         SourceLocation(),
 903         /*FirstQualifierFoundInScope=*/nullptr, NameInfo, /*TemplateArgs=*/nullptr);
 904   }
 905
 906   const RecordType *RT = T->getAs<RecordType>();
 907   // FIXME: Diagnose this as field access into a scalar type.
 908   if (!RT)
 909     return ExprResult();
 910
 911   LookupResult FieldResult(*this, &Context.Idents.get(Member), AsmLoc,
 912                            LookupMemberName);
 913
 914   if (!LookupQualifiedName(FieldResult, RT->getDecl()))
 915     return ExprResult();
 916
 917   // Only normal and indirect field results will work.
 918   ValueDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
 919   if (!FD)
 920     FD = dyn_cast<IndirectFieldDecl>(FieldResult.getFoundDecl());
 921   if (!FD)
 922     return ExprResult();
 923
 924   // Make an Expr to thread through OpDecl.
 925   ExprResult Result = BuildMemberReferenceExpr(
 926       E, E->getType(), AsmLoc, /*IsArrow=*/false, CXXScopeSpec(),
 927       SourceLocation(), nullptr, FieldResult, nullptr, nullptr);
 928
 929   return Result;
 930 }
 931
 932 StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
 933                                 ArrayRef<Token> AsmToks,
 934                                 StringRef AsmString,
 935                                 unsigned NumOutputs, unsigned NumInputs,
 936                                 ArrayRef<StringRef> Constraints,
 937                                 ArrayRef<StringRef> Clobbers,
 938                                 ArrayRef<Expr*> Exprs,
 939                                 SourceLocation EndLoc) {
 940   bool IsSimple = (NumOutputs != 0 || NumInputs != 0);
 941   setFunctionHasBranchProtectedScope();
 942
 943   bool InvalidOperand = false;
 944   for (uint64_t I = 0; I < NumOutputs + NumInputs; ++I) {
 945     Expr *E = Exprs[I];
 946     if (E->getType()->isBitIntType()) {
 947       InvalidOperand = true;
 948       Diag(E->getBeginLoc(), diag::err_asm_invalid_type)
 949           << E->getType() << (I < NumOutputs)
 950           << E->getSourceRange();
 951     } else if (E->refersToBitField()) {
 952       InvalidOperand = true;
 953       FieldDecl *BitField = E->getSourceBitField();
 954       Diag(E->getBeginLoc(), diag::err_ms_asm_bitfield_unsupported)
 955           << E->getSourceRange();
 956       Diag(BitField->getLocation(), diag::note_bitfield_decl);
 957     }
 958   }
 959   if (InvalidOperand)
 960     return StmtError();
 961
 962   MSAsmStmt *NS =
 963     new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
 964                             /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
 965                             Constraints, Exprs, AsmString,
 966                             Clobbers, EndLoc);
 967   return NS;
 968 }
 969
 970 LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
 971                                        SourceLocation Location,
 972                                        bool AlwaysCreate) {
 973   LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName),
 974                                          Location);
 975
 976   if (Label->isMSAsmLabel()) {
 977     // If we have previously created this label implicitly, mark it as used.
 978     Label->markUsed(Context);
 979   } else {
 980     // Otherwise, insert it, but only resolve it if we have seen the label itself.
 981     std::string InternalName;
 982     llvm::raw_string_ostream OS(InternalName);
 983     // Create an internal name for the label.  The name should not be a valid
 984     // mangled name, and should be unique.  We use a dot to make the name an
 985     // invalid mangled name. We use LLVM's inline asm ${:uid} escape so that a
 986     // unique label is generated each time this blob is emitted, even after
 987     // inlining or LTO.
 988     OS << "__MSASMLABEL_.${:uid}__";
 989     for (char C : ExternalLabelName) {
 990       OS << C;
 991       // We escape '$' in asm strings by replacing it with "$$"
 992       if (C == '$')
 993         OS << '$';
 994     }
 995     Label->setMSAsmLabel(OS.str());
 996   }
 997   if (AlwaysCreate) {
 998     // The label might have been created implicitly from a previously encountered
 999     // goto statement.  So, for both newly created and looked up labels, we mark
1000     // them as resolved.
1001     Label->setMSAsmLabelResolved();
1002   }
1003   // Adjust their location for being able to generate accurate diagnostics.
1004   Label->setLocation(Location);
1005
1006   return Label;
1007 }