[clang] d931ac9 - [clang][dataflow] Generalise match switch utility to other AST types and add a `CFGMatchSwitch` which currently handles `CFGStmt` and `CFGInitializer`.
Wei Yi Tee via cfe-commits
cfe-commits at lists.llvm.org
Thu Sep 1 03:16:59 PDT 2022
Author: Wei Yi Tee
Date: 2022-09-01T10:15:53Z
New Revision: d931ac9e27cab964c65078c80e4488185c62b3d8
URL: https://github.com/llvm/llvm-project/commit/d931ac9e27cab964c65078c80e4488185c62b3d8
DIFF: https://github.com/llvm/llvm-project/commit/d931ac9e27cab964c65078c80e4488185c62b3d8.diff
LOG: [clang][dataflow] Generalise match switch utility to other AST types and add a `CFGMatchSwitch` which currently handles `CFGStmt` and `CFGInitializer`.
`MatchSwitch` currently takes in matchers and functions for the `Stmt` class.
This patch generalises the match switch utility (renamed to `ASTMatchSwitch`) to work for different AST node types by introducing a template argument which is the base type for the AST nodes that the match switch will handle.
A `CFGMatchSwitch` is introduced as a wrapper around multiple `ASTMatchSwitch`s for different base types. It works by unwrapping `CFGElement`s into their contained AST nodes and passing the nodes to the relevant `ASTMatchSwitch`. The `CFGMatchSwitch` currently only handles `CFGStmt` and `CFGInitializer`.
Reviewed By: gribozavr2, sgatev
Differential Revision: https://reviews.llvm.org/D131616
Added:
clang/include/clang/Analysis/FlowSensitive/CFGMatchSwitch.h
clang/unittests/Analysis/FlowSensitive/CFGMatchSwitchTest.cpp
Modified:
clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h
clang/unittests/Analysis/FlowSensitive/CMakeLists.txt
clang/unittests/Analysis/FlowSensitive/MatchSwitchTest.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Analysis/FlowSensitive/CFGMatchSwitch.h b/clang/include/clang/Analysis/FlowSensitive/CFGMatchSwitch.h
new file mode 100644
index 0000000000000..ecd8558970f93
--- /dev/null
+++ b/clang/include/clang/Analysis/FlowSensitive/CFGMatchSwitch.h
@@ -0,0 +1,98 @@
+//===---- CFGMatchSwitch.h --------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the `CFGMatchSwitch` abstraction for building a "switch"
+// statement for control flow graph elements. Each case of the switch is
+// defined by an ASTMatcher which is applied on the AST node contained in the
+// input `CFGElement`.
+//
+// Currently, the `CFGMatchSwitch` only handles `CFGElement`s of
+// `Kind::Statement` and `Kind::Initializer`.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_CFGMATCHSWITCH_H_
+#define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_CFGMATCHSWITCH_H_
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Analysis/CFG.h"
+#include "clang/Analysis/FlowSensitive/MatchSwitch.h"
+#include <functional>
+#include <utility>
+
+namespace clang {
+namespace dataflow {
+
+template <typename State, typename Result = void>
+using CFGMatchSwitch =
+ std::function<Result(const CFGElement &, ASTContext &, State &)>;
+
+/// Collects cases of a "match switch": a collection of matchers paired with
+/// callbacks, which together define a switch that can be applied to an AST node
+/// contained in a CFG element.
+template <typename State, typename Result = void> class CFGMatchSwitchBuilder {
+public:
+ /// Registers an action `A` for `CFGStmt`s that will be triggered by the match
+ /// of the pattern `M` against the `Stmt` contained in the input `CFGStmt`.
+ ///
+ /// Requirements:
+ ///
+ /// `NodeT` should be derived from `Stmt`.
+ template <typename NodeT>
+ CFGMatchSwitchBuilder &&
+ CaseOfCFGStmt(MatchSwitchMatcher<Stmt> M,
+ MatchSwitchAction<NodeT, State, Result> A) && {
+ std::move(StmtBuilder).template CaseOf<NodeT>(M, A);
+ return std::move(*this);
+ }
+
+ /// Registers an action `A` for `CFGInitializer`s that will be triggered by
+ /// the match of the pattern `M` against the `CXXCtorInitializer` contained in
+ /// the input `CFGInitializer`.
+ ///
+ /// Requirements:
+ ///
+ /// `NodeT` should be derived from `CXXCtorInitializer`.
+ template <typename NodeT>
+ CFGMatchSwitchBuilder &&
+ CaseOfCFGInit(MatchSwitchMatcher<CXXCtorInitializer> M,
+ MatchSwitchAction<NodeT, State, Result> A) && {
+ std::move(InitBuilder).template CaseOf<NodeT>(M, A);
+ return std::move(*this);
+ }
+
+ CFGMatchSwitch<State, Result> Build() && {
+ return [StmtMS = std::move(StmtBuilder).Build(),
+ InitMS = std::move(InitBuilder).Build()](const CFGElement &Element,
+ ASTContext &Context,
+ State &S) -> Result {
+ switch (Element.getKind()) {
+ case CFGElement::Initializer:
+ return InitMS(*Element.castAs<CFGInitializer>().getInitializer(),
+ Context, S);
+ case CFGElement::Statement:
+ case CFGElement::Constructor:
+ case CFGElement::CXXRecordTypedCall:
+ return StmtMS(*Element.castAs<CFGStmt>().getStmt(), Context, S);
+ default:
+ // FIXME: Handle other kinds of CFGElement.
+ return Result();
+ }
+ };
+ }
+
+private:
+ ASTMatchSwitchBuilder<Stmt, State, Result> StmtBuilder;
+ ASTMatchSwitchBuilder<CXXCtorInitializer, State, Result> InitBuilder;
+};
+
+} // namespace dataflow
+} // namespace clang
+
+#endif // LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_CFGMATCHSWITCH_H_
diff --git a/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h b/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h
index 927aec7df5731..76d18c1d24463 100644
--- a/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h
+++ b/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h
@@ -16,6 +16,9 @@
// library may be generalized and moved to ASTMatchers.
//
//===----------------------------------------------------------------------===//
+//
+// FIXME: Rename to ASTMatchSwitch.h and update documentation when all usages of
+// `MatchSwitch` are updated to `ASTMatchSwitch<Stmt>`
#ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_MATCHSWITCH_H_
#define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_MATCHSWITCH_H_
@@ -28,6 +31,7 @@
#include "llvm/ADT/StringRef.h"
#include <functional>
#include <string>
+#include <type_traits>
#include <utility>
#include <vector>
@@ -44,23 +48,35 @@ template <typename LatticeT> struct TransferState {
Environment &Env;
};
-/// Matches against `Stmt` and, based on its structure, dispatches to an
-/// appropriate handler.
+template <typename T>
+using MatchSwitchMatcher = ast_matchers::internal::Matcher<T>;
+
+template <typename T, typename State, typename Result = void>
+using MatchSwitchAction = std::function<Result(
+ const T *, const ast_matchers::MatchFinder::MatchResult &, State &)>;
+
+template <typename BaseT, typename State, typename Result = void>
+using ASTMatchSwitch =
+ std::function<Result(const BaseT &, ASTContext &, State &)>;
+
+// FIXME: Remove this alias when all usages of `MatchSwitch` are updated to
+// `ASTMatchSwitch<Stmt>`.
template <typename State, typename Result = void>
-using MatchSwitch = std::function<Result(const Stmt &, ASTContext &, State &)>;
+using MatchSwitch = ASTMatchSwitch<Stmt, State, Result>;
/// Collects cases of a "match switch": a collection of matchers paired with
-/// callbacks, which together define a switch that can be applied to a
-/// `Stmt`. This structure can simplify the definition of `transfer` functions
-/// that rely on pattern-matching.
+/// callbacks, which together define a switch that can be applied to a node
+/// whose type derives from `BaseT`. This structure can simplify the definition
+/// of `transfer` functions that rely on pattern-matching.
///
/// For example, consider an analysis that handles particular function calls. It
-/// can define the `MatchSwitch` once, in the constructor of the analysis, and
-/// then reuse it each time that `transfer` is called, with a fresh state value.
+/// can define the `ASTMatchSwitch` once, in the constructor of the analysis,
+/// and then reuse it each time that `transfer` is called, with a fresh state
+/// value.
///
/// \code
-/// MatchSwitch<TransferState<MyLattice> BuildSwitch() {
-/// return MatchSwitchBuilder<TransferState<MyLattice>>()
+/// ASTMatchSwitch<Stmt, TransferState<MyLattice> BuildSwitch() {
+/// return ASTMatchSwitchBuilder<TransferState<MyLattice>>()
/// .CaseOf(callExpr(callee(functionDecl(hasName("foo")))), TransferFooCall)
/// .CaseOf(callExpr(argumentCountIs(2),
/// callee(functionDecl(hasName("bar")))),
@@ -68,35 +84,35 @@ using MatchSwitch = std::function<Result(const Stmt &, ASTContext &, State &)>;
/// .Build();
/// }
/// \endcode
-template <typename State, typename Result = void> class MatchSwitchBuilder {
+template <typename BaseT, typename State, typename Result = void>
+class ASTMatchSwitchBuilder {
public:
/// Registers an action that will be triggered by the match of a pattern
/// against the input statement.
///
/// Requirements:
///
- /// `Node` should be a subclass of `Stmt`.
- template <typename Node>
- MatchSwitchBuilder &&
- CaseOf(ast_matchers::internal::Matcher<Stmt> M,
- std::function<Result(const Node *,
- const ast_matchers::MatchFinder::MatchResult &,
- State &)>
- A) && {
+ /// `NodeT` should be derived from `BaseT`.
+ template <typename NodeT>
+ ASTMatchSwitchBuilder &&CaseOf(MatchSwitchMatcher<BaseT> M,
+ MatchSwitchAction<NodeT, State, Result> A) && {
+ static_assert(std::is_base_of<BaseT, NodeT>::value,
+ "NodeT must be derived from BaseT.");
Matchers.push_back(std::move(M));
Actions.push_back(
- [A = std::move(A)](const Stmt *Stmt,
+ [A = std::move(A)](const BaseT *Node,
const ast_matchers::MatchFinder::MatchResult &R,
- State &S) { return A(cast<Node>(Stmt), R, S); });
+ State &S) { return A(cast<NodeT>(Node), R, S); });
return std::move(*this);
}
- MatchSwitch<State, Result> Build() && {
+ ASTMatchSwitch<BaseT, State, Result> Build() && {
return [Matcher = BuildMatcher(), Actions = std::move(Actions)](
- const Stmt &Stmt, ASTContext &Context, State &S) -> Result {
- auto Results = ast_matchers::matchDynamic(Matcher, Stmt, Context);
- if (Results.empty())
+ const BaseT &Node, ASTContext &Context, State &S) -> Result {
+ auto Results = ast_matchers::matchDynamic(Matcher, Node, Context);
+ if (Results.empty()) {
return Result();
+ }
// Look through the map for the first binding of the form "TagN..." use
// that to select the action.
for (const auto &Element : Results[0].getMap()) {
@@ -105,7 +121,7 @@ template <typename State, typename Result = void> class MatchSwitchBuilder {
if (ID.consume_front("Tag") && !ID.getAsInteger(10, Index) &&
Index < Actions.size()) {
return Actions[Index](
- &Stmt,
+ &Node,
ast_matchers::MatchFinder::MatchResult(Results[0], &Context), S);
}
}
@@ -137,15 +153,19 @@ template <typename State, typename Result = void> class MatchSwitchBuilder {
// The matcher type on the cases ensures that `Expr` kind is compatible with
// all of the matchers.
return DynTypedMatcher::constructVariadic(
- DynTypedMatcher::VO_AnyOf, ASTNodeKind::getFromNodeKind<Stmt>(),
+ DynTypedMatcher::VO_AnyOf, ASTNodeKind::getFromNodeKind<BaseT>(),
std::move(Matchers));
}
std::vector<ast_matchers::internal::DynTypedMatcher> Matchers;
- std::vector<std::function<Result(
- const Stmt *, const ast_matchers::MatchFinder::MatchResult &, State &)>>
- Actions;
+ std::vector<MatchSwitchAction<BaseT, State, Result>> Actions;
};
+
+// FIXME: Remove this alias when all usages of `MatchSwitchBuilder` are updated
+// to `ASTMatchSwitchBuilder<Stmt>`.
+template <typename State, typename Result = void>
+using MatchSwitchBuilder = ASTMatchSwitchBuilder<Stmt, State, Result>;
+
} // namespace dataflow
} // namespace clang
#endif // LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_MATCHSWITCH_H_
diff --git a/clang/unittests/Analysis/FlowSensitive/CFGMatchSwitchTest.cpp b/clang/unittests/Analysis/FlowSensitive/CFGMatchSwitchTest.cpp
new file mode 100644
index 0000000000000..826b84cee529d
--- /dev/null
+++ b/clang/unittests/Analysis/FlowSensitive/CFGMatchSwitchTest.cpp
@@ -0,0 +1,124 @@
+//===- unittests/Analysis/FlowSensitive/CFGMatchSwitchTest.cpp ------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/FlowSensitive/CFGMatchSwitch.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Analysis/CFG.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/ADT/StringRef.h"
+#include "gtest/gtest.h"
+
+using namespace clang;
+using namespace dataflow;
+using namespace ast_matchers;
+
+namespace {
+// State for tracking the number of matches on each kind of CFGElement by the
+// CFGMatchSwitch. Currently only tracks CFGStmt and CFGInitializer.
+struct CFGElementMatches {
+ unsigned StmtMatches = 0;
+ unsigned InitializerMatches = 0;
+};
+
+// Returns a match switch that counts the number of local variables
+// (singly-declared) and fields initialized to the integer literal 42.
+auto buildCFGMatchSwitch() {
+ return CFGMatchSwitchBuilder<CFGElementMatches>()
+ .CaseOfCFGStmt<DeclStmt>(
+ declStmt(hasSingleDecl(
+ varDecl(hasInitializer(integerLiteral(equals(42)))))),
+ [](const DeclStmt *, const MatchFinder::MatchResult &,
+ CFGElementMatches &Counter) { Counter.StmtMatches++; })
+ .CaseOfCFGInit<CXXCtorInitializer>(
+ cxxCtorInitializer(withInitializer(integerLiteral(equals(42)))),
+ [](const CXXCtorInitializer *, const MatchFinder::MatchResult &,
+ CFGElementMatches &Counter) { Counter.InitializerMatches++; })
+ .Build();
+}
+
+// Runs the match switch `MS` on the control flow graph generated from `Code`,
+// tracking information in state `S`. For simplicity, this test utility is
+// restricted to CFGs with a single control flow block (excluding entry and
+// exit blocks) - generated by `Code` with sequential flow (i.e. no branching).
+//
+// Requirements:
+//
+// `Code` must contain a function named `f`, the body of this function will be
+// used to generate the CFG.
+template <typename State>
+void applySwitchToCode(CFGMatchSwitch<State> &MS, State &S,
+ llvm::StringRef Code) {
+ auto Unit = tooling::buildASTFromCodeWithArgs(Code, {"-Wno-unused-value"});
+ auto &Ctx = Unit->getASTContext();
+ const auto *F = selectFirst<FunctionDecl>(
+ "f", match(functionDecl(isDefinition(), hasName("f")).bind("f"), Ctx));
+
+ CFG::BuildOptions BO;
+ BO.AddInitializers = true;
+
+ auto CFG = CFG::buildCFG(F, F->getBody(), &Ctx, BO);
+ auto CFGBlock = *CFG->getEntry().succ_begin();
+ for (auto &Elt : CFGBlock->Elements) {
+ MS(Elt, Ctx, S);
+ }
+}
+
+TEST(CFGMatchSwitchTest, NoInitializationTo42) {
+ CFGMatchSwitch<CFGElementMatches> Switch = buildCFGMatchSwitch();
+ CFGElementMatches Counter;
+ applySwitchToCode(Switch, Counter, R"(
+ void f() {
+ 42;
+ }
+ )");
+ EXPECT_EQ(Counter.StmtMatches, 0u);
+ EXPECT_EQ(Counter.InitializerMatches, 0u);
+}
+
+TEST(CFGMatchSwitchTest, SingleLocalVarInitializationTo42) {
+ CFGMatchSwitch<CFGElementMatches> Switch = buildCFGMatchSwitch();
+ CFGElementMatches Counter;
+ applySwitchToCode(Switch, Counter, R"(
+ void f() {
+ int i = 42;
+ }
+ )");
+ EXPECT_EQ(Counter.StmtMatches, 1u);
+ EXPECT_EQ(Counter.InitializerMatches, 0u);
+}
+
+TEST(CFGMatchSwitchTest, SingleFieldInitializationTo42) {
+ CFGMatchSwitch<CFGElementMatches> Switch = buildCFGMatchSwitch();
+ CFGElementMatches Counter;
+ applySwitchToCode(Switch, Counter, R"(
+ struct f {
+ int i;
+ f(): i(42) {}
+ };
+ )");
+ EXPECT_EQ(Counter.StmtMatches, 0u);
+ EXPECT_EQ(Counter.InitializerMatches, 1u);
+}
+
+TEST(CFGMatchSwitchTest, LocalVarAndFieldInitializationTo42) {
+ CFGMatchSwitch<CFGElementMatches> Switch = buildCFGMatchSwitch();
+ CFGElementMatches Counter;
+ applySwitchToCode(Switch, Counter, R"(
+ struct f {
+ int i;
+ f(): i(42) {
+ int j = 42;
+ }
+ };
+ )");
+ EXPECT_EQ(Counter.StmtMatches, 1u);
+ EXPECT_EQ(Counter.InitializerMatches, 1u);
+}
+} // namespace
diff --git a/clang/unittests/Analysis/FlowSensitive/CMakeLists.txt b/clang/unittests/Analysis/FlowSensitive/CMakeLists.txt
index 8ce2549df36d6..85499ecb30010 100644
--- a/clang/unittests/Analysis/FlowSensitive/CMakeLists.txt
+++ b/clang/unittests/Analysis/FlowSensitive/CMakeLists.txt
@@ -4,6 +4,7 @@ set(LLVM_LINK_COMPONENTS
)
add_clang_unittest(ClangAnalysisFlowSensitiveTests
+ CFGMatchSwitchTest.cpp
ChromiumCheckModelTest.cpp
DataflowAnalysisContextTest.cpp
DataflowEnvironmentTest.cpp
diff --git a/clang/unittests/Analysis/FlowSensitive/MatchSwitchTest.cpp b/clang/unittests/Analysis/FlowSensitive/MatchSwitchTest.cpp
index bf8c2f5eedc95..90cc4a19ac7fc 100644
--- a/clang/unittests/Analysis/FlowSensitive/MatchSwitchTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/MatchSwitchTest.cpp
@@ -5,12 +5,6 @@
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
-//
-// This file defines a simplistic version of Constant Propagation as an example
-// of a forward, monotonic dataflow analysis. The analysis tracks all
-// variables in the scope, but lacks escape analysis.
-//
-//===----------------------------------------------------------------------===//
#include "clang/Analysis/FlowSensitive/MatchSwitch.h"
#include "TestingSupport.h"
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