1 //===--- DefaultOperatorNewCheck.cpp - clang-tidy --------------------===// 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 #include "DefaultOperatorNewAlignmentCheck.h" 10 #include "clang/AST/ASTContext.h" 11 #include "clang/ASTMatchers/ASTMatchFinder.h" 12 #include "clang/Basic/TargetInfo.h" 13 14 using namespace clang::ast_matchers; 15 16 namespace clang::tidy::cert { 17 registerMatchers(MatchFinder * Finder)18void DefaultOperatorNewAlignmentCheck::registerMatchers(MatchFinder *Finder) { 19 Finder->addMatcher( 20 cxxNewExpr(unless(hasAnyPlacementArg(anything()))).bind("new"), this); 21 } 22 check(const MatchFinder::MatchResult & Result)23void DefaultOperatorNewAlignmentCheck::check( 24 const MatchFinder::MatchResult &Result) { 25 // Get the found 'new' expression. 26 const auto *NewExpr = Result.Nodes.getNodeAs<CXXNewExpr>("new"); 27 28 QualType T = NewExpr->getAllocatedType(); 29 // Dependent types do not have fixed alignment. 30 if (T->isDependentType()) 31 return; 32 const TagDecl *D = T->getAsTagDecl(); 33 // Alignment can not be obtained for undefined type. 34 if (!D || !D->getDefinition() || !D->isCompleteDefinition()) 35 return; 36 37 ASTContext &Context = D->getASTContext(); 38 39 // Check if no alignment was specified for the type. 40 if (!Context.isAlignmentRequired(T)) 41 return; 42 43 // The user-specified alignment (in bits). 44 unsigned SpecifiedAlignment = D->getMaxAlignment(); 45 // Double-check if no alignment was specified. 46 if (!SpecifiedAlignment) 47 return; 48 // The alignment used by default 'operator new' (in bits). 49 unsigned DefaultNewAlignment = Context.getTargetInfo().getNewAlign(); 50 51 bool OverAligned = SpecifiedAlignment > DefaultNewAlignment; 52 bool HasDefaultOperatorNew = 53 !NewExpr->getOperatorNew() || NewExpr->getOperatorNew()->isImplicit(); 54 55 unsigned CharWidth = Context.getTargetInfo().getCharWidth(); 56 if (HasDefaultOperatorNew && OverAligned) 57 diag(NewExpr->getBeginLoc(), 58 "allocation function returns a pointer with alignment %0 but the " 59 "over-aligned type being allocated requires alignment %1") 60 << (DefaultNewAlignment / CharWidth) 61 << (SpecifiedAlignment / CharWidth); 62 } 63 64 } // namespace clang::tidy::cert 65