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.
removeLValueToRValueCast(Expr * E)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.
emitAndFixInvalidAsmCastLValue(const Expr * LVal,Expr * BadArgument,Sema & S)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.
CheckAsmLValue(Expr * E,Sema & S)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
isOperandMentioned(unsigned OpNo,ArrayRef<GCCAsmStmt::AsmStringPiece> AsmStrPieces)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 
CheckNakedParmReference(Expr * E,Sema & S)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.
checkExprMemoryConstraintCompat(Sema & S,Expr * E,TargetInfo::ConstraintInfo & Info,bool is_input_expr)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 ""
extractRegisterName(const Expr * Expression,const TargetInfo & Target)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
getClobberConflictLocation(MultiExprArg Exprs,StringLiteral ** Constraints,StringLiteral ** Clobbers,int NumClobbers,unsigned NumLabels,const TargetInfo & Target,ASTContext & Cont)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 
ActOnGCCAsmStmt(SourceLocation AsmLoc,bool IsSimple,bool IsVolatile,unsigned NumOutputs,unsigned NumInputs,IdentifierInfo ** Names,MultiExprArg constraints,MultiExprArg Exprs,Expr * asmString,MultiExprArg clobbers,unsigned NumLabels,SourceLocation RParenLoc)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 
FillInlineAsmIdentifierInfo(Expr * Res,llvm::InlineAsmIdentifierInfo & Info)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 
LookupInlineAsmIdentifier(CXXScopeSpec & SS,SourceLocation TemplateKWLoc,UnqualifiedId & Id,bool IsUnevaluatedContext)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 
LookupInlineAsmField(StringRef Base,StringRef Member,unsigned & Offset,SourceLocation AsmLoc)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
LookupInlineAsmVarDeclField(Expr * E,StringRef Member,SourceLocation AsmLoc)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 
ActOnMSAsmStmt(SourceLocation AsmLoc,SourceLocation LBraceLoc,ArrayRef<Token> AsmToks,StringRef AsmString,unsigned NumOutputs,unsigned NumInputs,ArrayRef<StringRef> Constraints,ArrayRef<StringRef> Clobbers,ArrayRef<Expr * > Exprs,SourceLocation EndLoc)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 
GetOrCreateMSAsmLabel(StringRef ExternalLabelName,SourceLocation Location,bool AlwaysCreate)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 }
1008