xref: /openbsd/gnu/llvm/clang/lib/Sema/SemaStmtAsm.cpp (revision 12c85518)
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/StringSet.h"
26 #include "llvm/MC/MCParser/MCAsmParser.h"
27 #include <optional>
28 using namespace clang;
29 using namespace sema;
30 
31 /// Remove the upper-level LValueToRValue cast from an expression.
removeLValueToRValueCast(Expr * E)32 static void removeLValueToRValueCast(Expr *E) {
33   Expr *Parent = E;
34   Expr *ExprUnderCast = nullptr;
35   SmallVector<Expr *, 8> ParentsToUpdate;
36 
37   while (true) {
38     ParentsToUpdate.push_back(Parent);
39     if (auto *ParenE = dyn_cast<ParenExpr>(Parent)) {
40       Parent = ParenE->getSubExpr();
41       continue;
42     }
43 
44     Expr *Child = nullptr;
45     CastExpr *ParentCast = dyn_cast<CastExpr>(Parent);
46     if (ParentCast)
47       Child = ParentCast->getSubExpr();
48     else
49       return;
50 
51     if (auto *CastE = dyn_cast<CastExpr>(Child))
52       if (CastE->getCastKind() == CK_LValueToRValue) {
53         ExprUnderCast = CastE->getSubExpr();
54         // LValueToRValue cast inside GCCAsmStmt requires an explicit cast.
55         ParentCast->setSubExpr(ExprUnderCast);
56         break;
57       }
58     Parent = Child;
59   }
60 
61   // Update parent expressions to have same ValueType as the underlying.
62   assert(ExprUnderCast &&
63          "Should be reachable only if LValueToRValue cast was found!");
64   auto ValueKind = ExprUnderCast->getValueKind();
65   for (Expr *E : ParentsToUpdate)
66     E->setValueKind(ValueKind);
67 }
68 
69 /// Emit a warning about usage of "noop"-like casts for lvalues (GNU extension)
70 /// and fix the argument with removing LValueToRValue cast from the expression.
emitAndFixInvalidAsmCastLValue(const Expr * LVal,Expr * BadArgument,Sema & S)71 static void emitAndFixInvalidAsmCastLValue(const Expr *LVal, Expr *BadArgument,
72                                            Sema &S) {
73   if (!S.getLangOpts().HeinousExtensions) {
74     S.Diag(LVal->getBeginLoc(), diag::err_invalid_asm_cast_lvalue)
75         << BadArgument->getSourceRange();
76   } else {
77     S.Diag(LVal->getBeginLoc(), diag::warn_invalid_asm_cast_lvalue)
78         << BadArgument->getSourceRange();
79   }
80   removeLValueToRValueCast(BadArgument);
81 }
82 
83 /// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
84 /// ignore "noop" casts in places where an lvalue is required by an inline asm.
85 /// We emulate this behavior when -fheinous-gnu-extensions is specified, but
86 /// provide a strong guidance to not use it.
87 ///
88 /// This method checks to see if the argument is an acceptable l-value and
89 /// returns false if it is a case we can handle.
CheckAsmLValue(Expr * E,Sema & S)90 static bool CheckAsmLValue(Expr *E, Sema &S) {
91   // Type dependent expressions will be checked during instantiation.
92   if (E->isTypeDependent())
93     return false;
94 
95   if (E->isLValue())
96     return false;  // Cool, this is an lvalue.
97 
98   // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
99   // are supposed to allow.
100   const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
101   if (E != E2 && E2->isLValue()) {
102     emitAndFixInvalidAsmCastLValue(E2, E, S);
103     // Accept, even if we emitted an error diagnostic.
104     return false;
105   }
106 
107   // None of the above, just randomly invalid non-lvalue.
108   return true;
109 }
110 
111 /// isOperandMentioned - Return true if the specified operand # is mentioned
112 /// anywhere in the decomposed asm string.
113 static bool
isOperandMentioned(unsigned OpNo,ArrayRef<GCCAsmStmt::AsmStringPiece> AsmStrPieces)114 isOperandMentioned(unsigned OpNo,
115                    ArrayRef<GCCAsmStmt::AsmStringPiece> AsmStrPieces) {
116   for (unsigned p = 0, e = AsmStrPieces.size(); p != e; ++p) {
117     const GCCAsmStmt::AsmStringPiece &Piece = AsmStrPieces[p];
118     if (!Piece.isOperand())
119       continue;
120 
121     // If this is a reference to the input and if the input was the smaller
122     // one, then we have to reject this asm.
123     if (Piece.getOperandNo() == OpNo)
124       return true;
125   }
126   return false;
127 }
128 
CheckNakedParmReference(Expr * E,Sema & S)129 static bool CheckNakedParmReference(Expr *E, Sema &S) {
130   FunctionDecl *Func = dyn_cast<FunctionDecl>(S.CurContext);
131   if (!Func)
132     return false;
133   if (!Func->hasAttr<NakedAttr>())
134     return false;
135 
136   SmallVector<Expr*, 4> WorkList;
137   WorkList.push_back(E);
138   while (WorkList.size()) {
139     Expr *E = WorkList.pop_back_val();
140     if (isa<CXXThisExpr>(E)) {
141       S.Diag(E->getBeginLoc(), diag::err_asm_naked_this_ref);
142       S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
143       return true;
144     }
145     if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
146       if (isa<ParmVarDecl>(DRE->getDecl())) {
147         S.Diag(DRE->getBeginLoc(), diag::err_asm_naked_parm_ref);
148         S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
149         return true;
150       }
151     }
152     for (Stmt *Child : E->children()) {
153       if (Expr *E = dyn_cast_or_null<Expr>(Child))
154         WorkList.push_back(E);
155     }
156   }
157   return false;
158 }
159 
160 /// Returns true if given expression is not compatible with inline
161 /// assembly's memory constraint; false otherwise.
checkExprMemoryConstraintCompat(Sema & S,Expr * E,TargetInfo::ConstraintInfo & Info,bool is_input_expr)162 static bool checkExprMemoryConstraintCompat(Sema &S, Expr *E,
163                                             TargetInfo::ConstraintInfo &Info,
164                                             bool is_input_expr) {
165   enum {
166     ExprBitfield = 0,
167     ExprVectorElt,
168     ExprGlobalRegVar,
169     ExprSafeType
170   } EType = ExprSafeType;
171 
172   // Bitfields, vector elements and global register variables are not
173   // compatible.
174   if (E->refersToBitField())
175     EType = ExprBitfield;
176   else if (E->refersToVectorElement())
177     EType = ExprVectorElt;
178   else if (E->refersToGlobalRegisterVar())
179     EType = ExprGlobalRegVar;
180 
181   if (EType != ExprSafeType) {
182     S.Diag(E->getBeginLoc(), diag::err_asm_non_addr_value_in_memory_constraint)
183         << EType << is_input_expr << Info.getConstraintStr()
184         << E->getSourceRange();
185     return true;
186   }
187 
188   return false;
189 }
190 
191 // Extracting the register name from the Expression value,
192 // if there is no register name to extract, returns ""
extractRegisterName(const Expr * Expression,const TargetInfo & Target)193 static StringRef extractRegisterName(const Expr *Expression,
194                                      const TargetInfo &Target) {
195   Expression = Expression->IgnoreImpCasts();
196   if (const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(Expression)) {
197     // Handle cases where the expression is a variable
198     const VarDecl *Variable = dyn_cast<VarDecl>(AsmDeclRef->getDecl());
199     if (Variable && Variable->getStorageClass() == SC_Register) {
200       if (AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>())
201         if (Target.isValidGCCRegisterName(Attr->getLabel()))
202           return Target.getNormalizedGCCRegisterName(Attr->getLabel(), true);
203     }
204   }
205   return "";
206 }
207 
208 // Checks if there is a conflict between the input and output lists with the
209 // clobbers list. If there's a conflict, returns the location of the
210 // conflicted clobber, else returns nullptr
211 static SourceLocation
getClobberConflictLocation(MultiExprArg Exprs,StringLiteral ** Constraints,StringLiteral ** Clobbers,int NumClobbers,unsigned NumLabels,const TargetInfo & Target,ASTContext & Cont)212 getClobberConflictLocation(MultiExprArg Exprs, StringLiteral **Constraints,
213                            StringLiteral **Clobbers, int NumClobbers,
214                            unsigned NumLabels,
215                            const TargetInfo &Target, ASTContext &Cont) {
216   llvm::StringSet<> InOutVars;
217   // Collect all the input and output registers from the extended asm
218   // statement in order to check for conflicts with the clobber list
219   for (unsigned int i = 0; i < Exprs.size() - NumLabels; ++i) {
220     StringRef Constraint = Constraints[i]->getString();
221     StringRef InOutReg = Target.getConstraintRegister(
222         Constraint, extractRegisterName(Exprs[i], Target));
223     if (InOutReg != "")
224       InOutVars.insert(InOutReg);
225   }
226   // Check for each item in the clobber list if it conflicts with the input
227   // or output
228   for (int i = 0; i < NumClobbers; ++i) {
229     StringRef Clobber = Clobbers[i]->getString();
230     // We only check registers, therefore we don't check cc and memory
231     // clobbers
232     if (Clobber == "cc" || Clobber == "memory" || Clobber == "unwind")
233       continue;
234     Clobber = Target.getNormalizedGCCRegisterName(Clobber, true);
235     // Go over the output's registers we collected
236     if (InOutVars.count(Clobber))
237       return Clobbers[i]->getBeginLoc();
238   }
239   return SourceLocation();
240 }
241 
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)242 StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
243                                  bool IsVolatile, unsigned NumOutputs,
244                                  unsigned NumInputs, IdentifierInfo **Names,
245                                  MultiExprArg constraints, MultiExprArg Exprs,
246                                  Expr *asmString, MultiExprArg clobbers,
247                                  unsigned NumLabels,
248                                  SourceLocation RParenLoc) {
249   unsigned NumClobbers = clobbers.size();
250   StringLiteral **Constraints =
251     reinterpret_cast<StringLiteral**>(constraints.data());
252   StringLiteral *AsmString = cast<StringLiteral>(asmString);
253   StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.data());
254 
255   SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
256 
257   // The parser verifies that there is a string literal here.
258   assert(AsmString->isOrdinary());
259 
260   FunctionDecl *FD = dyn_cast<FunctionDecl>(getCurLexicalContext());
261   llvm::StringMap<bool> FeatureMap;
262   Context.getFunctionFeatureMap(FeatureMap, FD);
263 
264   for (unsigned i = 0; i != NumOutputs; i++) {
265     StringLiteral *Literal = Constraints[i];
266     assert(Literal->isOrdinary());
267 
268     StringRef OutputName;
269     if (Names[i])
270       OutputName = Names[i]->getName();
271 
272     TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
273     if (!Context.getTargetInfo().validateOutputConstraint(Info)) {
274       targetDiag(Literal->getBeginLoc(),
275                  diag::err_asm_invalid_output_constraint)
276           << Info.getConstraintStr();
277       return new (Context)
278           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
279                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
280                      NumClobbers, Clobbers, NumLabels, RParenLoc);
281     }
282 
283     ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
284     if (ER.isInvalid())
285       return StmtError();
286     Exprs[i] = ER.get();
287 
288     // Check that the output exprs are valid lvalues.
289     Expr *OutputExpr = Exprs[i];
290 
291     // Referring to parameters is not allowed in naked functions.
292     if (CheckNakedParmReference(OutputExpr, *this))
293       return StmtError();
294 
295     // Check that the output expression is compatible with memory constraint.
296     if (Info.allowsMemory() &&
297         checkExprMemoryConstraintCompat(*this, OutputExpr, Info, false))
298       return StmtError();
299 
300     // Disallow bit-precise integer types, since the backends tend to have
301     // difficulties with abnormal sizes.
302     if (OutputExpr->getType()->isBitIntType())
303       return StmtError(
304           Diag(OutputExpr->getBeginLoc(), diag::err_asm_invalid_type)
305           << OutputExpr->getType() << 0 /*Input*/
306           << OutputExpr->getSourceRange());
307 
308     OutputConstraintInfos.push_back(Info);
309 
310     // If this is dependent, just continue.
311     if (OutputExpr->isTypeDependent())
312       continue;
313 
314     Expr::isModifiableLvalueResult IsLV =
315         OutputExpr->isModifiableLvalue(Context, /*Loc=*/nullptr);
316     switch (IsLV) {
317     case Expr::MLV_Valid:
318       // Cool, this is an lvalue.
319       break;
320     case Expr::MLV_ArrayType:
321       // This is OK too.
322       break;
323     case Expr::MLV_LValueCast: {
324       const Expr *LVal = OutputExpr->IgnoreParenNoopCasts(Context);
325       emitAndFixInvalidAsmCastLValue(LVal, OutputExpr, *this);
326       // Accept, even if we emitted an error diagnostic.
327       break;
328     }
329     case Expr::MLV_IncompleteType:
330     case Expr::MLV_IncompleteVoidType:
331       if (RequireCompleteType(OutputExpr->getBeginLoc(), Exprs[i]->getType(),
332                               diag::err_dereference_incomplete_type))
333         return StmtError();
334       [[fallthrough]];
335     default:
336       return StmtError(Diag(OutputExpr->getBeginLoc(),
337                             diag::err_asm_invalid_lvalue_in_output)
338                        << OutputExpr->getSourceRange());
339     }
340 
341     unsigned Size = Context.getTypeSize(OutputExpr->getType());
342     if (!Context.getTargetInfo().validateOutputSize(
343             FeatureMap, Literal->getString(), Size)) {
344       targetDiag(OutputExpr->getBeginLoc(), diag::err_asm_invalid_output_size)
345           << Info.getConstraintStr();
346       return new (Context)
347           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
348                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
349                      NumClobbers, Clobbers, NumLabels, RParenLoc);
350     }
351   }
352 
353   SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
354 
355   for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
356     StringLiteral *Literal = Constraints[i];
357     assert(Literal->isOrdinary());
358 
359     StringRef InputName;
360     if (Names[i])
361       InputName = Names[i]->getName();
362 
363     TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
364     if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos,
365                                                          Info)) {
366       targetDiag(Literal->getBeginLoc(), diag::err_asm_invalid_input_constraint)
367           << Info.getConstraintStr();
368       return new (Context)
369           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
370                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
371                      NumClobbers, Clobbers, NumLabels, RParenLoc);
372     }
373 
374     ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
375     if (ER.isInvalid())
376       return StmtError();
377     Exprs[i] = ER.get();
378 
379     Expr *InputExpr = Exprs[i];
380 
381     if (InputExpr->getType()->isMemberPointerType())
382       return StmtError(Diag(InputExpr->getBeginLoc(),
383                             diag::err_asm_pmf_through_constraint_not_permitted)
384                        << InputExpr->getSourceRange());
385 
386     // Referring to parameters is not allowed in naked functions.
387     if (CheckNakedParmReference(InputExpr, *this))
388       return StmtError();
389 
390     // Check that the input expression is compatible with memory constraint.
391     if (Info.allowsMemory() &&
392         checkExprMemoryConstraintCompat(*this, InputExpr, Info, true))
393       return StmtError();
394 
395     // Only allow void types for memory constraints.
396     if (Info.allowsMemory() && !Info.allowsRegister()) {
397       if (CheckAsmLValue(InputExpr, *this))
398         return StmtError(Diag(InputExpr->getBeginLoc(),
399                               diag::err_asm_invalid_lvalue_in_input)
400                          << Info.getConstraintStr()
401                          << InputExpr->getSourceRange());
402     } else {
403       ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
404       if (Result.isInvalid())
405         return StmtError();
406 
407       InputExpr = Exprs[i] = Result.get();
408 
409       if (Info.requiresImmediateConstant() && !Info.allowsRegister()) {
410         if (!InputExpr->isValueDependent()) {
411           Expr::EvalResult EVResult;
412           if (InputExpr->EvaluateAsRValue(EVResult, Context, true)) {
413             // For compatibility with GCC, we also allow pointers that would be
414             // integral constant expressions if they were cast to int.
415             llvm::APSInt IntResult;
416             if (EVResult.Val.toIntegralConstant(IntResult, InputExpr->getType(),
417                                                 Context))
418               if (!Info.isValidAsmImmediate(IntResult))
419                 return StmtError(
420                     Diag(InputExpr->getBeginLoc(),
421                          diag::err_invalid_asm_value_for_constraint)
422                     << toString(IntResult, 10) << Info.getConstraintStr()
423                     << InputExpr->getSourceRange());
424           }
425         }
426       }
427     }
428 
429     if (Info.allowsRegister()) {
430       if (InputExpr->getType()->isVoidType()) {
431         return StmtError(
432             Diag(InputExpr->getBeginLoc(), diag::err_asm_invalid_type_in_input)
433             << InputExpr->getType() << Info.getConstraintStr()
434             << InputExpr->getSourceRange());
435       }
436     }
437 
438     if (InputExpr->getType()->isBitIntType())
439       return StmtError(
440           Diag(InputExpr->getBeginLoc(), diag::err_asm_invalid_type)
441           << InputExpr->getType() << 1 /*Output*/
442           << InputExpr->getSourceRange());
443 
444     InputConstraintInfos.push_back(Info);
445 
446     const Type *Ty = Exprs[i]->getType().getTypePtr();
447     if (Ty->isDependentType())
448       continue;
449 
450     if (!Ty->isVoidType() || !Info.allowsMemory())
451       if (RequireCompleteType(InputExpr->getBeginLoc(), Exprs[i]->getType(),
452                               diag::err_dereference_incomplete_type))
453         return StmtError();
454 
455     unsigned Size = Context.getTypeSize(Ty);
456     if (!Context.getTargetInfo().validateInputSize(FeatureMap,
457                                                    Literal->getString(), Size))
458       return targetDiag(InputExpr->getBeginLoc(),
459                         diag::err_asm_invalid_input_size)
460              << Info.getConstraintStr();
461   }
462 
463   std::optional<SourceLocation> UnwindClobberLoc;
464 
465   // Check that the clobbers are valid.
466   for (unsigned i = 0; i != NumClobbers; i++) {
467     StringLiteral *Literal = Clobbers[i];
468     assert(Literal->isOrdinary());
469 
470     StringRef Clobber = Literal->getString();
471 
472     if (!Context.getTargetInfo().isValidClobber(Clobber)) {
473       targetDiag(Literal->getBeginLoc(), diag::err_asm_unknown_register_name)
474           << Clobber;
475       return new (Context)
476           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
477                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
478                      NumClobbers, Clobbers, NumLabels, RParenLoc);
479     }
480 
481     if (Clobber == "unwind") {
482       UnwindClobberLoc = Literal->getBeginLoc();
483     }
484   }
485 
486   // Using unwind clobber and asm-goto together is not supported right now.
487   if (UnwindClobberLoc && NumLabels > 0) {
488     targetDiag(*UnwindClobberLoc, diag::err_asm_unwind_and_goto);
489     return new (Context)
490         GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs,
491                    Names, Constraints, Exprs.data(), AsmString, NumClobbers,
492                    Clobbers, NumLabels, RParenLoc);
493   }
494 
495   GCCAsmStmt *NS =
496     new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
497                              NumInputs, Names, Constraints, Exprs.data(),
498                              AsmString, NumClobbers, Clobbers, NumLabels,
499                              RParenLoc);
500   // Validate the asm string, ensuring it makes sense given the operands we
501   // have.
502   SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
503   unsigned DiagOffs;
504   if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
505     targetDiag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
506         << AsmString->getSourceRange();
507     return NS;
508   }
509 
510   // Validate constraints and modifiers.
511   for (unsigned i = 0, e = Pieces.size(); i != e; ++i) {
512     GCCAsmStmt::AsmStringPiece &Piece = Pieces[i];
513     if (!Piece.isOperand()) continue;
514 
515     // Look for the correct constraint index.
516     unsigned ConstraintIdx = Piece.getOperandNo();
517     unsigned NumOperands = NS->getNumOutputs() + NS->getNumInputs();
518     // Labels are the last in the Exprs list.
519     if (NS->isAsmGoto() && ConstraintIdx >= NumOperands)
520       continue;
521     // Look for the (ConstraintIdx - NumOperands + 1)th constraint with
522     // modifier '+'.
523     if (ConstraintIdx >= NumOperands) {
524       unsigned I = 0, E = NS->getNumOutputs();
525 
526       for (unsigned Cnt = ConstraintIdx - NumOperands; I != E; ++I)
527         if (OutputConstraintInfos[I].isReadWrite() && Cnt-- == 0) {
528           ConstraintIdx = I;
529           break;
530         }
531 
532       assert(I != E && "Invalid operand number should have been caught in "
533                        " AnalyzeAsmString");
534     }
535 
536     // Now that we have the right indexes go ahead and check.
537     StringLiteral *Literal = Constraints[ConstraintIdx];
538     const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr();
539     if (Ty->isDependentType() || Ty->isIncompleteType())
540       continue;
541 
542     unsigned Size = Context.getTypeSize(Ty);
543     std::string SuggestedModifier;
544     if (!Context.getTargetInfo().validateConstraintModifier(
545             Literal->getString(), Piece.getModifier(), Size,
546             SuggestedModifier)) {
547       targetDiag(Exprs[ConstraintIdx]->getBeginLoc(),
548                  diag::warn_asm_mismatched_size_modifier);
549 
550       if (!SuggestedModifier.empty()) {
551         auto B = targetDiag(Piece.getRange().getBegin(),
552                             diag::note_asm_missing_constraint_modifier)
553                  << SuggestedModifier;
554         SuggestedModifier = "%" + SuggestedModifier + Piece.getString();
555         B << FixItHint::CreateReplacement(Piece.getRange(), SuggestedModifier);
556       }
557     }
558   }
559 
560   // Validate tied input operands for type mismatches.
561   unsigned NumAlternatives = ~0U;
562   for (unsigned i = 0, e = OutputConstraintInfos.size(); i != e; ++i) {
563     TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
564     StringRef ConstraintStr = Info.getConstraintStr();
565     unsigned AltCount = ConstraintStr.count(',') + 1;
566     if (NumAlternatives == ~0U) {
567       NumAlternatives = AltCount;
568     } else if (NumAlternatives != AltCount) {
569       targetDiag(NS->getOutputExpr(i)->getBeginLoc(),
570                  diag::err_asm_unexpected_constraint_alternatives)
571           << NumAlternatives << AltCount;
572       return NS;
573     }
574   }
575   SmallVector<size_t, 4> InputMatchedToOutput(OutputConstraintInfos.size(),
576                                               ~0U);
577   for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
578     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
579     StringRef ConstraintStr = Info.getConstraintStr();
580     unsigned AltCount = ConstraintStr.count(',') + 1;
581     if (NumAlternatives == ~0U) {
582       NumAlternatives = AltCount;
583     } else if (NumAlternatives != AltCount) {
584       targetDiag(NS->getInputExpr(i)->getBeginLoc(),
585                  diag::err_asm_unexpected_constraint_alternatives)
586           << NumAlternatives << AltCount;
587       return NS;
588     }
589 
590     // If this is a tied constraint, verify that the output and input have
591     // either exactly the same type, or that they are int/ptr operands with the
592     // same size (int/long, int*/long, are ok etc).
593     if (!Info.hasTiedOperand()) continue;
594 
595     unsigned TiedTo = Info.getTiedOperand();
596     unsigned InputOpNo = i+NumOutputs;
597     Expr *OutputExpr = Exprs[TiedTo];
598     Expr *InputExpr = Exprs[InputOpNo];
599 
600     // Make sure no more than one input constraint matches each output.
601     assert(TiedTo < InputMatchedToOutput.size() && "TiedTo value out of range");
602     if (InputMatchedToOutput[TiedTo] != ~0U) {
603       targetDiag(NS->getInputExpr(i)->getBeginLoc(),
604                  diag::err_asm_input_duplicate_match)
605           << TiedTo;
606       targetDiag(NS->getInputExpr(InputMatchedToOutput[TiedTo])->getBeginLoc(),
607                  diag::note_asm_input_duplicate_first)
608           << TiedTo;
609       return NS;
610     }
611     InputMatchedToOutput[TiedTo] = i;
612 
613     if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
614       continue;
615 
616     QualType InTy = InputExpr->getType();
617     QualType OutTy = OutputExpr->getType();
618     if (Context.hasSameType(InTy, OutTy))
619       continue;  // All types can be tied to themselves.
620 
621     // Decide if the input and output are in the same domain (integer/ptr or
622     // floating point.
623     enum AsmDomain {
624       AD_Int, AD_FP, AD_Other
625     } InputDomain, OutputDomain;
626 
627     if (InTy->isIntegerType() || InTy->isPointerType())
628       InputDomain = AD_Int;
629     else if (InTy->isRealFloatingType())
630       InputDomain = AD_FP;
631     else
632       InputDomain = AD_Other;
633 
634     if (OutTy->isIntegerType() || OutTy->isPointerType())
635       OutputDomain = AD_Int;
636     else if (OutTy->isRealFloatingType())
637       OutputDomain = AD_FP;
638     else
639       OutputDomain = AD_Other;
640 
641     // They are ok if they are the same size and in the same domain.  This
642     // allows tying things like:
643     //   void* to int*
644     //   void* to int            if they are the same size.
645     //   double to long double   if they are the same size.
646     //
647     uint64_t OutSize = Context.getTypeSize(OutTy);
648     uint64_t InSize = Context.getTypeSize(InTy);
649     if (OutSize == InSize && InputDomain == OutputDomain &&
650         InputDomain != AD_Other)
651       continue;
652 
653     // If the smaller input/output operand is not mentioned in the asm string,
654     // then we can promote the smaller one to a larger input and the asm string
655     // won't notice.
656     bool SmallerValueMentioned = false;
657 
658     // If this is a reference to the input and if the input was the smaller
659     // one, then we have to reject this asm.
660     if (isOperandMentioned(InputOpNo, Pieces)) {
661       // This is a use in the asm string of the smaller operand.  Since we
662       // codegen this by promoting to a wider value, the asm will get printed
663       // "wrong".
664       SmallerValueMentioned |= InSize < OutSize;
665     }
666     if (isOperandMentioned(TiedTo, Pieces)) {
667       // If this is a reference to the output, and if the output is the larger
668       // value, then it's ok because we'll promote the input to the larger type.
669       SmallerValueMentioned |= OutSize < InSize;
670     }
671 
672     // If the smaller value wasn't mentioned in the asm string, and if the
673     // output was a register, just extend the shorter one to the size of the
674     // larger one.
675     if (!SmallerValueMentioned && InputDomain != AD_Other &&
676         OutputConstraintInfos[TiedTo].allowsRegister()) {
677       // FIXME: GCC supports the OutSize to be 128 at maximum. Currently codegen
678       // crash when the size larger than the register size. So we limit it here.
679       if (OutTy->isStructureType() &&
680           Context.getIntTypeForBitwidth(OutSize, /*Signed*/ false).isNull()) {
681         targetDiag(OutputExpr->getExprLoc(), diag::err_store_value_to_reg);
682         return NS;
683       }
684 
685       continue;
686     }
687 
688     // Either both of the operands were mentioned or the smaller one was
689     // mentioned.  One more special case that we'll allow: if the tied input is
690     // integer, unmentioned, and is a constant, then we'll allow truncating it
691     // down to the size of the destination.
692     if (InputDomain == AD_Int && OutputDomain == AD_Int &&
693         !isOperandMentioned(InputOpNo, Pieces) &&
694         InputExpr->isEvaluatable(Context)) {
695       CastKind castKind =
696         (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast);
697       InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).get();
698       Exprs[InputOpNo] = InputExpr;
699       NS->setInputExpr(i, InputExpr);
700       continue;
701     }
702 
703     targetDiag(InputExpr->getBeginLoc(), diag::err_asm_tying_incompatible_types)
704         << InTy << OutTy << OutputExpr->getSourceRange()
705         << InputExpr->getSourceRange();
706     return NS;
707   }
708 
709   // Check for conflicts between clobber list and input or output lists
710   SourceLocation ConstraintLoc =
711       getClobberConflictLocation(Exprs, Constraints, Clobbers, NumClobbers,
712                                  NumLabels,
713                                  Context.getTargetInfo(), Context);
714   if (ConstraintLoc.isValid())
715     targetDiag(ConstraintLoc, diag::error_inoutput_conflict_with_clobber);
716 
717   // Check for duplicate asm operand name between input, output and label lists.
718   typedef std::pair<StringRef , Expr *> NamedOperand;
719   SmallVector<NamedOperand, 4> NamedOperandList;
720   for (unsigned i = 0, e = NumOutputs + NumInputs + NumLabels; i != e; ++i)
721     if (Names[i])
722       NamedOperandList.emplace_back(
723           std::make_pair(Names[i]->getName(), Exprs[i]));
724   // Sort NamedOperandList.
725   llvm::stable_sort(NamedOperandList, llvm::less_first());
726   // Find adjacent duplicate operand.
727   SmallVector<NamedOperand, 4>::iterator Found =
728       std::adjacent_find(begin(NamedOperandList), end(NamedOperandList),
729                          [](const NamedOperand &LHS, const NamedOperand &RHS) {
730                            return LHS.first == RHS.first;
731                          });
732   if (Found != NamedOperandList.end()) {
733     Diag((Found + 1)->second->getBeginLoc(),
734          diag::error_duplicate_asm_operand_name)
735         << (Found + 1)->first;
736     Diag(Found->second->getBeginLoc(), diag::note_duplicate_asm_operand_name)
737         << Found->first;
738     return StmtError();
739   }
740   if (NS->isAsmGoto())
741     setFunctionHasBranchIntoScope();
742 
743   CleanupVarDeclMarking();
744   DiscardCleanupsInEvaluationContext();
745   return NS;
746 }
747 
FillInlineAsmIdentifierInfo(Expr * Res,llvm::InlineAsmIdentifierInfo & Info)748 void Sema::FillInlineAsmIdentifierInfo(Expr *Res,
749                                        llvm::InlineAsmIdentifierInfo &Info) {
750   QualType T = Res->getType();
751   Expr::EvalResult Eval;
752   if (T->isFunctionType() || T->isDependentType())
753     return Info.setLabel(Res);
754   if (Res->isPRValue()) {
755     bool IsEnum = isa<clang::EnumType>(T);
756     if (DeclRefExpr *DRE = dyn_cast<clang::DeclRefExpr>(Res))
757       if (DRE->getDecl()->getKind() == Decl::EnumConstant)
758         IsEnum = true;
759     if (IsEnum && Res->EvaluateAsRValue(Eval, Context))
760       return Info.setEnum(Eval.Val.getInt().getSExtValue());
761 
762     return Info.setLabel(Res);
763   }
764   unsigned Size = Context.getTypeSizeInChars(T).getQuantity();
765   unsigned Type = Size;
766   if (const auto *ATy = Context.getAsArrayType(T))
767     Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity();
768   bool IsGlobalLV = false;
769   if (Res->EvaluateAsLValue(Eval, Context))
770     IsGlobalLV = Eval.isGlobalLValue();
771   Info.setVar(Res, IsGlobalLV, Size, Type);
772 }
773 
LookupInlineAsmIdentifier(CXXScopeSpec & SS,SourceLocation TemplateKWLoc,UnqualifiedId & Id,bool IsUnevaluatedContext)774 ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS,
775                                            SourceLocation TemplateKWLoc,
776                                            UnqualifiedId &Id,
777                                            bool IsUnevaluatedContext) {
778 
779   if (IsUnevaluatedContext)
780     PushExpressionEvaluationContext(
781         ExpressionEvaluationContext::UnevaluatedAbstract,
782         ReuseLambdaContextDecl);
783 
784   ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id,
785                                         /*trailing lparen*/ false,
786                                         /*is & operand*/ false,
787                                         /*CorrectionCandidateCallback=*/nullptr,
788                                         /*IsInlineAsmIdentifier=*/ true);
789 
790   if (IsUnevaluatedContext)
791     PopExpressionEvaluationContext();
792 
793   if (!Result.isUsable()) return Result;
794 
795   Result = CheckPlaceholderExpr(Result.get());
796   if (!Result.isUsable()) return Result;
797 
798   // Referring to parameters is not allowed in naked functions.
799   if (CheckNakedParmReference(Result.get(), *this))
800     return ExprError();
801 
802   QualType T = Result.get()->getType();
803 
804   if (T->isDependentType()) {
805     return Result;
806   }
807 
808   // Any sort of function type is fine.
809   if (T->isFunctionType()) {
810     return Result;
811   }
812 
813   // Otherwise, it needs to be a complete type.
814   if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) {
815     return ExprError();
816   }
817 
818   return Result;
819 }
820 
LookupInlineAsmField(StringRef Base,StringRef Member,unsigned & Offset,SourceLocation AsmLoc)821 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
822                                 unsigned &Offset, SourceLocation AsmLoc) {
823   Offset = 0;
824   SmallVector<StringRef, 2> Members;
825   Member.split(Members, ".");
826 
827   NamedDecl *FoundDecl = nullptr;
828 
829   // MS InlineAsm uses 'this' as a base
830   if (getLangOpts().CPlusPlus && Base.equals("this")) {
831     if (const Type *PT = getCurrentThisType().getTypePtrOrNull())
832       FoundDecl = PT->getPointeeType()->getAsTagDecl();
833   } else {
834     LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
835                             LookupOrdinaryName);
836     if (LookupName(BaseResult, getCurScope()) && BaseResult.isSingleResult())
837       FoundDecl = BaseResult.getFoundDecl();
838   }
839 
840   if (!FoundDecl)
841     return true;
842 
843   for (StringRef NextMember : Members) {
844     const RecordType *RT = nullptr;
845     if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl))
846       RT = VD->getType()->getAs<RecordType>();
847     else if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(FoundDecl)) {
848       MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
849       // MS InlineAsm often uses struct pointer aliases as a base
850       QualType QT = TD->getUnderlyingType();
851       if (const auto *PT = QT->getAs<PointerType>())
852         QT = PT->getPointeeType();
853       RT = QT->getAs<RecordType>();
854     } else if (TypeDecl *TD = dyn_cast<TypeDecl>(FoundDecl))
855       RT = TD->getTypeForDecl()->getAs<RecordType>();
856     else if (FieldDecl *TD = dyn_cast<FieldDecl>(FoundDecl))
857       RT = TD->getType()->getAs<RecordType>();
858     if (!RT)
859       return true;
860 
861     if (RequireCompleteType(AsmLoc, QualType(RT, 0),
862                             diag::err_asm_incomplete_type))
863       return true;
864 
865     LookupResult FieldResult(*this, &Context.Idents.get(NextMember),
866                              SourceLocation(), LookupMemberName);
867 
868     if (!LookupQualifiedName(FieldResult, RT->getDecl()))
869       return true;
870 
871     if (!FieldResult.isSingleResult())
872       return true;
873     FoundDecl = FieldResult.getFoundDecl();
874 
875     // FIXME: Handle IndirectFieldDecl?
876     FieldDecl *FD = dyn_cast<FieldDecl>(FoundDecl);
877     if (!FD)
878       return true;
879 
880     const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
881     unsigned i = FD->getFieldIndex();
882     CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
883     Offset += (unsigned)Result.getQuantity();
884   }
885 
886   return false;
887 }
888 
889 ExprResult
LookupInlineAsmVarDeclField(Expr * E,StringRef Member,SourceLocation AsmLoc)890 Sema::LookupInlineAsmVarDeclField(Expr *E, StringRef Member,
891                                   SourceLocation AsmLoc) {
892 
893   QualType T = E->getType();
894   if (T->isDependentType()) {
895     DeclarationNameInfo NameInfo;
896     NameInfo.setLoc(AsmLoc);
897     NameInfo.setName(&Context.Idents.get(Member));
898     return CXXDependentScopeMemberExpr::Create(
899         Context, E, T, /*IsArrow=*/false, AsmLoc, NestedNameSpecifierLoc(),
900         SourceLocation(),
901         /*FirstQualifierFoundInScope=*/nullptr, NameInfo, /*TemplateArgs=*/nullptr);
902   }
903 
904   const RecordType *RT = T->getAs<RecordType>();
905   // FIXME: Diagnose this as field access into a scalar type.
906   if (!RT)
907     return ExprResult();
908 
909   LookupResult FieldResult(*this, &Context.Idents.get(Member), AsmLoc,
910                            LookupMemberName);
911 
912   if (!LookupQualifiedName(FieldResult, RT->getDecl()))
913     return ExprResult();
914 
915   // Only normal and indirect field results will work.
916   ValueDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
917   if (!FD)
918     FD = dyn_cast<IndirectFieldDecl>(FieldResult.getFoundDecl());
919   if (!FD)
920     return ExprResult();
921 
922   // Make an Expr to thread through OpDecl.
923   ExprResult Result = BuildMemberReferenceExpr(
924       E, E->getType(), AsmLoc, /*IsArrow=*/false, CXXScopeSpec(),
925       SourceLocation(), nullptr, FieldResult, nullptr, nullptr);
926 
927   return Result;
928 }
929 
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)930 StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
931                                 ArrayRef<Token> AsmToks,
932                                 StringRef AsmString,
933                                 unsigned NumOutputs, unsigned NumInputs,
934                                 ArrayRef<StringRef> Constraints,
935                                 ArrayRef<StringRef> Clobbers,
936                                 ArrayRef<Expr*> Exprs,
937                                 SourceLocation EndLoc) {
938   bool IsSimple = (NumOutputs != 0 || NumInputs != 0);
939   setFunctionHasBranchProtectedScope();
940 
941   bool InvalidOperand = false;
942   for (uint64_t I = 0; I < NumOutputs + NumInputs; ++I) {
943     Expr *E = Exprs[I];
944     if (E->getType()->isBitIntType()) {
945       InvalidOperand = true;
946       Diag(E->getBeginLoc(), diag::err_asm_invalid_type)
947           << E->getType() << (I < NumOutputs)
948           << E->getSourceRange();
949     } else if (E->refersToBitField()) {
950       InvalidOperand = true;
951       FieldDecl *BitField = E->getSourceBitField();
952       Diag(E->getBeginLoc(), diag::err_ms_asm_bitfield_unsupported)
953           << E->getSourceRange();
954       Diag(BitField->getLocation(), diag::note_bitfield_decl);
955     }
956   }
957   if (InvalidOperand)
958     return StmtError();
959 
960   MSAsmStmt *NS =
961     new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
962                             /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
963                             Constraints, Exprs, AsmString,
964                             Clobbers, EndLoc);
965   return NS;
966 }
967 
GetOrCreateMSAsmLabel(StringRef ExternalLabelName,SourceLocation Location,bool AlwaysCreate)968 LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
969                                        SourceLocation Location,
970                                        bool AlwaysCreate) {
971   LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName),
972                                          Location);
973 
974   if (Label->isMSAsmLabel()) {
975     // If we have previously created this label implicitly, mark it as used.
976     Label->markUsed(Context);
977   } else {
978     // Otherwise, insert it, but only resolve it if we have seen the label itself.
979     std::string InternalName;
980     llvm::raw_string_ostream OS(InternalName);
981     // Create an internal name for the label.  The name should not be a valid
982     // mangled name, and should be unique.  We use a dot to make the name an
983     // invalid mangled name. We use LLVM's inline asm ${:uid} escape so that a
984     // unique label is generated each time this blob is emitted, even after
985     // inlining or LTO.
986     OS << "__MSASMLABEL_.${:uid}__";
987     for (char C : ExternalLabelName) {
988       OS << C;
989       // We escape '$' in asm strings by replacing it with "$$"
990       if (C == '$')
991         OS << '$';
992     }
993     Label->setMSAsmLabel(OS.str());
994   }
995   if (AlwaysCreate) {
996     // The label might have been created implicitly from a previously encountered
997     // goto statement.  So, for both newly created and looked up labels, we mark
998     // them as resolved.
999     Label->setMSAsmLabelResolved();
1000   }
1001   // Adjust their location for being able to generate accurate diagnostics.
1002   Label->setLocation(Location);
1003 
1004   return Label;
1005 }
1006