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