1//===- BugSuppression.cpp - Suppression interface -------------------------===//
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 "clang/StaticAnalyzer/Core/BugReporter/BugSuppression.h"
10#include "clang/AST/DynamicRecursiveASTVisitor.h"
11#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
12#include "llvm/Support/FormatVariadic.h"
13#include "llvm/Support/TimeProfiler.h"
14
15using namespace clang;
16using namespace ento;
17
18namespace {
19
20using Ranges = llvm::SmallVectorImpl<SourceRange>;
21
22inline bool hasSuppression(const Decl *D) {
23 // FIXME: Implement diagnostic identifier arguments
24 // (checker names, "hashtags").
25 if (const auto *Suppression = D->getAttr<SuppressAttr>())
26 return !Suppression->isGSL() &&
27 (Suppression->diagnosticIdentifiers().empty());
28 return false;
29}
30inline bool hasSuppression(const AttributedStmt *S) {
31 // FIXME: Implement diagnostic identifier arguments
32 // (checker names, "hashtags").
33 return llvm::any_of(Range: S->getAttrs(), P: [](const Attr *A) {
34 const auto *Suppression = dyn_cast<SuppressAttr>(Val: A);
35 return Suppression && !Suppression->isGSL() &&
36 (Suppression->diagnosticIdentifiers().empty());
37 });
38}
39
40template <class NodeType> inline SourceRange getRange(const NodeType *Node) {
41 return Node->getSourceRange();
42}
43template <> inline SourceRange getRange(const AttributedStmt *S) {
44 // Begin location for attributed statement node seems to be ALWAYS invalid.
45 //
46 // It is unlikely that we ever report any warnings on suppression
47 // attribute itself, but even if we do, we wouldn't want that warning
48 // to be suppressed by that same attribute.
49 //
50 // Long story short, we can use inner statement and it's not going to break
51 // anything.
52 return getRange(Node: S->getSubStmt());
53}
54
55inline bool isLessOrEqual(SourceLocation LHS, SourceLocation RHS,
56 const SourceManager &SM) {
57 // SourceManager::isBeforeInTranslationUnit tests for strict
58 // inequality, when we need a non-strict comparison (bug
59 // can be reported directly on the annotated note).
60 // For this reason, we use the following equivalence:
61 //
62 // A <= B <==> !(B < A)
63 //
64 return !SM.isBeforeInTranslationUnit(LHS: RHS, RHS: LHS);
65}
66
67inline bool fullyContains(SourceRange Larger, SourceRange Smaller,
68 const SourceManager &SM) {
69 // Essentially this means:
70 //
71 // Larger.fullyContains(Smaller)
72 //
73 // However, that method has a very trivial implementation and couldn't
74 // compare regular locations and locations from macro expansions.
75 // We could've converted everything into regular locations as a solution,
76 // but the following solution seems to be the most bulletproof.
77 return isLessOrEqual(LHS: Larger.getBegin(), RHS: Smaller.getBegin(), SM) &&
78 isLessOrEqual(LHS: Smaller.getEnd(), RHS: Larger.getEnd(), SM);
79}
80
81class CacheInitializer : public DynamicRecursiveASTVisitor {
82public:
83 static void initialize(const Decl *D, Ranges &ToInit) {
84 CacheInitializer(ToInit).TraverseDecl(D: const_cast<Decl *>(D));
85 }
86
87 bool VisitDecl(Decl *D) override {
88 // Bug location could be somewhere in the init value of
89 // a freshly declared variable. Even though it looks like the
90 // user applied attribute to a statement, it will apply to a
91 // variable declaration, and this is where we check for it.
92 return VisitAttributedNode(Node: D);
93 }
94
95 bool VisitAttributedStmt(AttributedStmt *AS) override {
96 // When we apply attributes to statements, it actually creates
97 // a wrapper statement that only contains attributes and the wrapped
98 // statement.
99 return VisitAttributedNode(Node: AS);
100 }
101
102private:
103 template <class NodeType> bool VisitAttributedNode(NodeType *Node) {
104 if (hasSuppression(Node)) {
105 // TODO: In the future, when we come up with good stable IDs for checkers
106 // we can return a list of kinds to ignore, or all if no arguments
107 // were provided.
108 addRange(R: getRange(Node));
109 }
110 // We should keep traversing AST.
111 return true;
112 }
113
114 void addRange(SourceRange R) {
115 if (R.isValid()) {
116 Result.push_back(Elt: R);
117 }
118 }
119
120 CacheInitializer(Ranges &R) : Result(R) {}
121 Ranges &Result;
122};
123
124std::string timeScopeName(const Decl *DeclWithIssue) {
125 if (!llvm::timeTraceProfilerEnabled())
126 return "";
127 return llvm::formatv(
128 Fmt: "BugSuppression::isSuppressed init suppressions cache for {0}",
129 Vals: DeclWithIssue->getDeclKindName())
130 .str();
131}
132
133llvm::TimeTraceMetadata getDeclTimeTraceMetadata(const Decl *DeclWithIssue) {
134 assert(DeclWithIssue);
135 assert(llvm::timeTraceProfilerEnabled());
136 std::string Name = "<noname>";
137 if (const auto *ND = dyn_cast<NamedDecl>(Val: DeclWithIssue)) {
138 Name = ND->getNameAsString();
139 }
140 const auto &SM = DeclWithIssue->getASTContext().getSourceManager();
141 auto Line = SM.getPresumedLineNumber(Loc: DeclWithIssue->getBeginLoc());
142 auto Fname = SM.getFilename(SpellingLoc: DeclWithIssue->getBeginLoc());
143 return llvm::TimeTraceMetadata{.Detail: std::move(Name), .File: Fname.str(),
144 .Line: static_cast<int>(Line)};
145}
146
147} // end anonymous namespace
148
149// TODO: Introduce stable IDs for checkers and check for those here
150// to be more specific. Attribute without arguments should still
151// be considered as "suppress all".
152// It is already much finer granularity than what we have now
153// (i.e. removing the whole function from the analysis).
154bool BugSuppression::isSuppressed(const BugReport &R) {
155 PathDiagnosticLocation Location = R.getLocation();
156 PathDiagnosticLocation UniqueingLocation = R.getUniqueingLocation();
157 const Decl *DeclWithIssue = R.getDeclWithIssue();
158
159 return isSuppressed(Location, DeclWithIssue, DiagnosticIdentification: {}) ||
160 isSuppressed(Location: UniqueingLocation, DeclWithIssue, DiagnosticIdentification: {});
161}
162
163bool BugSuppression::isSuppressed(const PathDiagnosticLocation &Location,
164 const Decl *DeclWithIssue,
165 DiagnosticIdentifierList Hashtags) {
166 if (!Location.isValid())
167 return false;
168
169 if (!DeclWithIssue) {
170 // FIXME: This defeats the purpose of passing DeclWithIssue to begin with.
171 // If this branch is ever hit, we're re-doing all the work we've already
172 // done as well as perform a lot of work we'll never need.
173 // Gladly, none of our on-by-default checkers currently need it.
174 DeclWithIssue = ACtx.getTranslationUnitDecl();
175 } else {
176 // This is the fast path. However, we should still consider the topmost
177 // declaration that isn't TranslationUnitDecl, because we should respect
178 // attributes on the entire declaration chain.
179 while (true) {
180 // Use the "lexical" parent. Eg., if the attribute is on a class, suppress
181 // warnings in inline methods but not in out-of-line methods.
182 const Decl *Parent =
183 dyn_cast_or_null<Decl>(Val: DeclWithIssue->getLexicalDeclContext());
184 if (Parent == nullptr || isa<TranslationUnitDecl>(Val: Parent))
185 break;
186
187 DeclWithIssue = Parent;
188 }
189 }
190
191 // While some warnings are attached to AST nodes (mostly path-sensitive
192 // checks), others are simply associated with a plain source location
193 // or range. Figuring out the node based on locations can be tricky,
194 // so instead, we traverse the whole body of the declaration and gather
195 // information on ALL suppressions. After that we can simply check if
196 // any of those suppressions affect the warning in question.
197 //
198 // Traversing AST of a function is not a heavy operation, but for
199 // large functions with a lot of bugs it can make a dent in performance.
200 // In order to avoid this scenario, we cache traversal results.
201 auto InsertionResult = CachedSuppressionLocations.insert(
202 KV: std::make_pair(x&: DeclWithIssue, y: CachedRanges{}));
203 Ranges &SuppressionRanges = InsertionResult.first->second;
204 if (InsertionResult.second) {
205 llvm::TimeTraceScope TimeScope(
206 timeScopeName(DeclWithIssue),
207 [DeclWithIssue]() { return getDeclTimeTraceMetadata(DeclWithIssue); });
208 // We haven't checked this declaration for suppressions yet!
209 CacheInitializer::initialize(D: DeclWithIssue, ToInit&: SuppressionRanges);
210 }
211
212 SourceRange BugRange = Location.asRange();
213 const SourceManager &SM = Location.getManager();
214
215 return llvm::any_of(Range&: SuppressionRanges,
216 P: [BugRange, &SM](SourceRange Suppression) {
217 return fullyContains(Larger: Suppression, Smaller: BugRange, SM);
218 });
219}
220