| 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 | |
| 18 | void DefaultOperatorNewAlignmentCheck::registerMatchers(MatchFinder *Finder) { |
| 19 | Finder->addMatcher( |
| 20 | NodeMatch: cxxNewExpr(unless(hasAnyPlacementArg(InnerMatcher: anything()))).bind(ID: "new"), Action: this); |
| 21 | } |
| 22 | |
| 23 | void DefaultOperatorNewAlignmentCheck::check( |
| 24 | const MatchFinder::MatchResult &Result) { |
| 25 | // Get the found 'new' expression. |
| 26 | const auto *NewExpr = Result.Nodes.getNodeAs<CXXNewExpr>(ID: "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(Loc: NewExpr->getBeginLoc(), |
| 58 | Description: "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 |