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 { 17 namespace tidy { 18 namespace cert { 19 registerMatchers(MatchFinder * Finder)20void DefaultOperatorNewAlignmentCheck::registerMatchers(MatchFinder *Finder) { 21 Finder->addMatcher( 22 cxxNewExpr(unless(hasAnyPlacementArg(anything()))).bind("new"), this); 23 } 24 check(const MatchFinder::MatchResult & Result)25void DefaultOperatorNewAlignmentCheck::check( 26 const MatchFinder::MatchResult &Result) { 27 // Get the found 'new' expression. 28 const auto *NewExpr = Result.Nodes.getNodeAs<CXXNewExpr>("new"); 29 30 QualType T = NewExpr->getAllocatedType(); 31 // Dependent types do not have fixed alignment. 32 if (T->isDependentType()) 33 return; 34 const TagDecl *D = T->getAsTagDecl(); 35 // Alignment can not be obtained for undefined type. 36 if (!D || !D->getDefinition() || !D->isCompleteDefinition()) 37 return; 38 39 ASTContext &Context = D->getASTContext(); 40 41 // Check if no alignment was specified for the type. 42 if (!Context.isAlignmentRequired(T)) 43 return; 44 45 // The user-specified alignment (in bits). 46 unsigned SpecifiedAlignment = D->getMaxAlignment(); 47 // Double-check if no alignment was specified. 48 if (!SpecifiedAlignment) 49 return; 50 // The alignment used by default 'operator new' (in bits). 51 unsigned DefaultNewAlignment = Context.getTargetInfo().getNewAlign(); 52 53 bool OverAligned = SpecifiedAlignment > DefaultNewAlignment; 54 bool HasDefaultOperatorNew = 55 !NewExpr->getOperatorNew() || NewExpr->getOperatorNew()->isImplicit(); 56 57 unsigned CharWidth = Context.getTargetInfo().getCharWidth(); 58 if (HasDefaultOperatorNew && OverAligned) 59 diag(NewExpr->getBeginLoc(), 60 "allocation function returns a pointer with alignment %0 but the " 61 "over-aligned type being allocated requires alignment %1") 62 << (DefaultNewAlignment / CharWidth) 63 << (SpecifiedAlignment / CharWidth); 64 } 65 66 } // namespace cert 67 } // namespace tidy 68 } // namespace clang 69