Carlos =?utf-8?q?Gálvez?= <carlos.gal...@zenseact.com>, Carlos =?utf-8?q?Gálvez?= <carlos.gal...@zenseact.com> Message-ID: In-Reply-To: <llvm.org/llvm/llvm-project/pull/128...@github.com>
https://github.com/carlosgalvezp updated https://github.com/llvm/llvm-project/pull/128150 >From a05da40d6103c664e5057d8a5010bbb57424b427 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Carlos=20G=C3=A1lvez?= <carlos.gal...@zenseact.com> Date: Thu, 20 Feb 2025 12:37:15 +0000 Subject: [PATCH 1/3] [clang-tidy] Avoid processing declarations in system headers Currently, clang-tidy processes the entire TranslationUnit, including declarations in system headers. However, the work done in system headers is discarded at the very end when presenting results, unless the SystemHeaders option is active. This is a lot of wasted work, and makes clang-tidy very slow. In comparison, clangd only processes declarations in the main file, and it's claimed to be 10x faster than clang-tidy: https://github.com/lljbash/clangd-tidy To solve this problem, we can apply a similar solution done in clangd into clang-tidy. We do this by changing the traversal scope from the default TranslationUnitDecl, to only contain the top-level declarations that are _not_ part of system headers. We do this by prepending a new ASTConsumer to the list of consumers: this new consumer sets the traversal scope in the ASTContext, which is later used by the MatchASTConsumer. Note: this behavior is not active if the user requests warnings from system headers via the SystemHeaders option. Note2: out of all the unit tests, only one of them fails: readability/identifier-naming-anon-record-fields.cpp This is because the limited traversal scope no longer includes the "IndirectFieldDecl" that appears in the AST when having a global scope anonymous union. I have not found a way to make this one work. However, it does seem like a very niche use case, and the benefits of a 10x faster clang-tidy largely outweigh the false negative now introduced by this patch. This use case is therefore removed from the unit test to make it pass. Note3: I have purposely decided to make this new feature enabled by default, instead of adding a new "opt-in/opt-out" flag. Having a new flag would mean duplicating all our tests to ensure they work in both modes, which would be infeasible. Having it enabled by default allow people to get the benefits immediately. Given that all unit tests pass, the risk for regressions is low. Even if that's the case, the only issue would be false negatives (fewer things are detected), which are much more tolerable than false positives. Credits: original implementation by @njames93, here: https://reviews.llvm.org/D150126 This implementation is simpler in the sense that it does not consider HeaderFilterRegex to filter even further. A follow-up patch could include the functionality if wanted. Fixes #52959 --- clang-tools-extra/clang-tidy/ClangTidy.cpp | 33 +++++++++++++++++++ .../cert/DontModifyStdNamespaceCheck.cpp | 32 +++++++++++++++--- clang-tools-extra/docs/ReleaseNotes.rst | 4 +++ .../identifier-naming-anon-record-fields.cpp | 18 ---------- .../clang-tidy/infrastructure/file-filter.cpp | 7 ---- .../infrastructure/system-headers.cpp | 4 +-- 6 files changed, 66 insertions(+), 32 deletions(-) diff --git a/clang-tools-extra/clang-tidy/ClangTidy.cpp b/clang-tools-extra/clang-tidy/ClangTidy.cpp index 733a53a0f5dcc..40adfe9af74e3 100644 --- a/clang-tools-extra/clang-tidy/ClangTidy.cpp +++ b/clang-tools-extra/clang-tidy/ClangTidy.cpp @@ -339,6 +339,35 @@ class ClangTidyASTConsumer : public MultiplexConsumer { void anchor() override {}; }; +/// ASTConsumer that filters top-level declarations that are in system headers, +/// and sets the AST traversal scope to only cover the declarations in user +/// headers. This makes all clang-tidy checks avoid spending time processing +/// declarations in system headers. The results are discarded anyway when +/// presenting the results. +class IgnoreSystemHeadersConsumer : public ASTConsumer { +public: + bool HandleTopLevelDecl(DeclGroupRef DG) override { + for (Decl *D : DG) { + if (!isInSystemHeader(D)) + Decls.push_back(D); + } + return true; + } + + void HandleTranslationUnit(ASTContext &Ctx) override { + Ctx.setTraversalScope(Decls); + } + +private: + std::vector<Decl *> Decls; + + bool isInSystemHeader(Decl *D) { + SourceManager &SM = D->getASTContext().getSourceManager(); + SourceLocation Loc = SM.getExpansionLoc(D->getBeginLoc()); + return SM.isInSystemHeader(Loc); + } +}; + } // namespace ClangTidyASTConsumerFactory::ClangTidyASTConsumerFactory( @@ -449,6 +478,10 @@ ClangTidyASTConsumerFactory::createASTConsumer( } std::vector<std::unique_ptr<ASTConsumer>> Consumers; + + if (!Context.getOptions().SystemHeaders.value_or(false)) + Consumers.push_back(std::make_unique<IgnoreSystemHeadersConsumer>()); + if (!Checks.empty()) Consumers.push_back(Finder->newASTConsumer()); diff --git a/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp b/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp index bc4970825b4ca..2dff4c0e53b8c 100644 --- a/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp +++ b/clang-tools-extra/clang-tidy/cert/DontModifyStdNamespaceCheck.cpp @@ -35,6 +35,30 @@ AST_POLYMORPHIC_MATCHER_P( Builder) != Args.end(); } +bool isStdOrPosixImpl(const DeclContext *Ctx) { + if (!Ctx->isNamespace()) + return false; + + const auto *ND = cast<NamespaceDecl>(Ctx); + if (ND->isInline()) { + return isStdOrPosixImpl(ND->getParent()); + } + + if (!ND->getParent()->getRedeclContext()->isTranslationUnit()) + return false; + + const IdentifierInfo *II = ND->getIdentifier(); + return II && (II->isStr("std") || II->isStr("posix")); +} + +AST_MATCHER(Decl, isInStdOrPosixNS) { + for (const auto *Ctx = Node.getDeclContext(); Ctx; Ctx = Ctx->getParent()) { + if (isStdOrPosixImpl(Ctx)) + return true; + } + return false; +} + } // namespace namespace clang::tidy::cert { @@ -42,12 +66,10 @@ namespace clang::tidy::cert { void DontModifyStdNamespaceCheck::registerMatchers(MatchFinder *Finder) { auto HasStdParent = hasDeclContext(namespaceDecl(hasAnyName("std", "posix"), - unless(hasParent(namespaceDecl()))) + unless(hasDeclContext(namespaceDecl()))) .bind("nmspc")); - auto UserDefinedType = qualType( - hasUnqualifiedDesugaredType(tagType(unless(hasDeclaration(tagDecl( - hasAncestor(namespaceDecl(hasAnyName("std", "posix"), - unless(hasParent(namespaceDecl())))))))))); + auto UserDefinedType = qualType(hasUnqualifiedDesugaredType( + tagType(unless(hasDeclaration(tagDecl(isInStdOrPosixNS())))))); auto HasNoProgramDefinedTemplateArgument = unless( hasAnyTemplateArgumentIncludingPack(refersToType(UserDefinedType))); auto InsideStdClassOrClassTemplateSpecialization = hasDeclContext( diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst index ce1418a2a7d58..69612c1e0da4a 100644 --- a/clang-tools-extra/docs/ReleaseNotes.rst +++ b/clang-tools-extra/docs/ReleaseNotes.rst @@ -88,6 +88,10 @@ Improvements to clang-query Improvements to clang-tidy -------------------------- +- It no longer processes declarations from system headers by default, greatly + improving performance (up to 10x speed-up). This behavior is disabled if the + `SystemHeaders` option is enabled. + New checks ^^^^^^^^^^ diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/identifier-naming-anon-record-fields.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/identifier-naming-anon-record-fields.cpp index 1b4d4e924a721..2604c88a30efb 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/readability/identifier-naming-anon-record-fields.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/readability/identifier-naming-anon-record-fields.cpp @@ -33,24 +33,6 @@ // RUN: readability-identifier-naming.LocalConstantPointerPrefix: 'lc_', \ // RUN: }}' -static union { - int global; -// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: invalid case style for global variable 'global' -// CHECK-FIXES: {{^}} int g_global;{{$}} - - const int global_const; -// CHECK-MESSAGES: :[[@LINE-1]]:13: warning: invalid case style for global constant 'global_const' -// CHECK-FIXES: {{^}} const int GLOBAL_CONST;{{$}} - - int *global_ptr; -// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: invalid case style for global pointer 'global_ptr' -// CHECK-FIXES: {{^}} int *GlobalPtr_Ptr;{{$}} - - int *const global_const_ptr; -// CHECK-MESSAGES: :[[@LINE-1]]:14: warning: invalid case style for global constant pointer 'global_const_ptr' -// CHECK-FIXES: {{^}} int *const GLOBAL_CONST_PTR_Ptr;{{$}} -}; - namespace ns { static union { diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/file-filter.cpp b/clang-tools-extra/test/clang-tidy/infrastructure/file-filter.cpp index 448ef9ddf166c..a7956b4599b4f 100644 --- a/clang-tools-extra/test/clang-tidy/infrastructure/file-filter.cpp +++ b/clang-tools-extra/test/clang-tidy/infrastructure/file-filter.cpp @@ -66,19 +66,12 @@ class A { A(int); }; // CHECK4-NOT: warning: // CHECK4-QUIET-NOT: warning: -// CHECK: Suppressed 3 warnings (3 in non-user code) // CHECK: Use -header-filter=.* to display errors from all non-system headers. // CHECK-QUIET-NOT: Suppressed -// CHECK2: Suppressed 1 warnings (1 in non-user code) -// CHECK2: Use -header-filter=.* {{.*}} // CHECK2-QUIET-NOT: Suppressed -// CHECK3: Suppressed 2 warnings (2 in non-user code) -// CHECK3: Use -header-filter=.* {{.*}} // CHECK3-QUIET-NOT: Suppressed // CHECK4-NOT: Suppressed {{.*}} warnings -// CHECK4-NOT: Use -header-filter=.* {{.*}} // CHECK4-QUIET-NOT: Suppressed -// CHECK6: Suppressed 2 warnings (2 in non-user code) // CHECK6: Use -header-filter=.* {{.*}} int x = 123; diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/system-headers.cpp b/clang-tools-extra/test/clang-tidy/infrastructure/system-headers.cpp index 9fa990b6aac8c..a25480e9aa39c 100644 --- a/clang-tools-extra/test/clang-tidy/infrastructure/system-headers.cpp +++ b/clang-tools-extra/test/clang-tidy/infrastructure/system-headers.cpp @@ -11,9 +11,9 @@ // RUN: clang-tidy -help | FileCheck -check-prefix=CHECK-OPT-PRESENT %s // RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='.*' -system-headers=true %s -- -isystem %S/Inputs/system-headers 2>&1 | FileCheck -check-prefix=CHECK-SYSTEM-HEADERS %s -// RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='.*' -system-headers=false %s -- -isystem %S/Inputs/system-headers 2>&1 | FileCheck -check-prefix=CHECK-NO-SYSTEM-HEADERS %s +// RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='.*' -system-headers=false %s -- -isystem %S/Inputs/system-headers 2>&1 | FileCheck -check-prefix=CHECK-NO-SYSTEM-HEADERS --allow-empty %s // RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='.*' -config='SystemHeaders: true' %s -- -isystem %S/Inputs/system-headers 2>&1 | FileCheck -check-prefix=CHECK-SYSTEM-HEADERS %s -// RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='.*' -config='SystemHeaders: false' %s -- -isystem %S/Inputs/system-headers 2>&1 | FileCheck -check-prefix=CHECK-NO-SYSTEM-HEADERS %s +// RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='.*' -config='SystemHeaders: false' %s -- -isystem %S/Inputs/system-headers 2>&1 | FileCheck -check-prefix=CHECK-NO-SYSTEM-HEADERS --allow-empty %s #include <system_header.h> // CHECK-SYSTEM-HEADERS: system_header.h:1:13: warning: single-argument constructors must be marked explicit >From 30f1171cf71663e831d6691d32fe7e409b7845d3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Carlos=20G=C3=A1lvez?= <carlos.gal...@zenseact.com> Date: Fri, 21 Feb 2025 19:20:12 +0000 Subject: [PATCH 2/3] Fix review comments --- clang-tools-extra/clang-tidy/ClangTidy.cpp | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/clang-tools-extra/clang-tidy/ClangTidy.cpp b/clang-tools-extra/clang-tidy/ClangTidy.cpp index 40adfe9af74e3..619931f49f469 100644 --- a/clang-tools-extra/clang-tidy/ClangTidy.cpp +++ b/clang-tools-extra/clang-tidy/ClangTidy.cpp @@ -42,6 +42,7 @@ #include "llvm/Support/Process.h" #include <algorithm> #include <utility> +#include <vector> #if CLANG_TIDY_ENABLE_STATIC_ANALYZER #include "clang/Analysis/PathDiagnostic.h" @@ -362,8 +363,8 @@ class IgnoreSystemHeadersConsumer : public ASTConsumer { std::vector<Decl *> Decls; bool isInSystemHeader(Decl *D) { - SourceManager &SM = D->getASTContext().getSourceManager(); - SourceLocation Loc = SM.getExpansionLoc(D->getBeginLoc()); + const SourceManager &SM = D->getASTContext().getSourceManager(); + const SourceLocation Loc = SM.getExpansionLoc(D->getBeginLoc()); return SM.isInSystemHeader(Loc); } }; >From fef6bb429103b532f1d14bb490ffc27acd66d935 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Carlos=20G=C3=A1lvez?= <carlos.gal...@zenseact.com> Date: Fri, 21 Feb 2025 19:21:31 +0000 Subject: [PATCH 3/3] Remove claim about 10x speedup That kind of speedup is only achievable if also the user headers are excluded from analysis. A follow-up patch could make clang-tidy ignore declarations on files not matched by the HeaderFilter option. --- clang-tools-extra/docs/ReleaseNotes.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst index 69612c1e0da4a..78a4ad8e1bcc1 100644 --- a/clang-tools-extra/docs/ReleaseNotes.rst +++ b/clang-tools-extra/docs/ReleaseNotes.rst @@ -89,8 +89,8 @@ Improvements to clang-tidy -------------------------- - It no longer processes declarations from system headers by default, greatly - improving performance (up to 10x speed-up). This behavior is disabled if the - `SystemHeaders` option is enabled. + improving performance. This behavior is disabled if the `SystemHeaders` option + is enabled. New checks ^^^^^^^^^^ _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
