[clang] [clang][dataflow] Correctly handle `InitListExpr` of union type. (PR #82348)
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Tue Feb 20 04:06:04 PST 2024
https://github.com/martinboehme created https://github.com/llvm/llvm-project/pull/82348
None
>From fc41d1efdcff94857e7ccd3b8a1a75c3e83a84ee Mon Sep 17 00:00:00 2001
From: Martin Braenne <mboehme at google.com>
Date: Tue, 20 Feb 2024 11:57:23 +0000
Subject: [PATCH] [clang][dataflow] Correctly handle `InitListExpr` of union
type.
---
.../FlowSensitive/DataflowEnvironment.h | 9 ++++---
.../FlowSensitive/DataflowEnvironment.cpp | 18 ++++++++++---
clang/lib/Analysis/FlowSensitive/Transfer.cpp | 26 +++++++++++--------
.../Analysis/FlowSensitive/TestingSupport.h | 19 ++++++++++++++
.../Analysis/FlowSensitive/TransferTest.cpp | 14 ++++++++--
5 files changed, 66 insertions(+), 20 deletions(-)
diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h b/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h
index 0aecc749bf415c..b3dc940705f870 100644
--- a/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h
+++ b/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h
@@ -753,9 +753,12 @@ RecordStorageLocation *getImplicitObjectLocation(const CXXMemberCallExpr &MCE,
RecordStorageLocation *getBaseObjectLocation(const MemberExpr &ME,
const Environment &Env);
-/// Returns the fields of `RD` that are initialized by an `InitListExpr`, in the
-/// order in which they appear in `InitListExpr::inits()`.
-std::vector<FieldDecl *> getFieldsForInitListExpr(const RecordDecl *RD);
+/// Returns the fields of a `RecordDecl` that are initialized by an
+/// `InitListExpr`, in the order in which they appear in
+/// `InitListExpr::inits()`.
+/// `Init->getType()` must be a record type.
+std::vector<const FieldDecl *>
+getFieldsForInitListExpr(const InitListExpr *InitList);
/// Associates a new `RecordValue` with `Loc` and returns the new value.
RecordValue &refreshRecordValue(RecordStorageLocation &Loc, Environment &Env);
diff --git a/clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp b/clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
index d487944ce92111..0cfc26ea952cda 100644
--- a/clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
+++ b/clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp
@@ -361,8 +361,8 @@ getFieldsGlobalsAndFuncs(const Stmt &S, FieldSet &Fields,
if (const auto *FD = dyn_cast<FieldDecl>(VD))
Fields.insert(FD);
} else if (auto *InitList = dyn_cast<InitListExpr>(&S)) {
- if (RecordDecl *RD = InitList->getType()->getAsRecordDecl())
- for (const auto *FD : getFieldsForInitListExpr(RD))
+ if (InitList->getType()->isRecordType())
+ for (const auto *FD : getFieldsForInitListExpr(InitList))
Fields.insert(FD);
}
}
@@ -1104,12 +1104,22 @@ RecordStorageLocation *getBaseObjectLocation(const MemberExpr &ME,
return Env.get<RecordStorageLocation>(*Base);
}
-std::vector<FieldDecl *> getFieldsForInitListExpr(const RecordDecl *RD) {
+std::vector<const FieldDecl *>
+getFieldsForInitListExpr(const InitListExpr *InitList) {
+ const RecordDecl *RD = InitList->getType()->getAsRecordDecl();
+ assert(RD != nullptr);
+
+ std::vector<const FieldDecl *> Fields;
+
+ if (InitList->getType()->isUnionType()) {
+ Fields.push_back(InitList->getInitializedFieldInUnion());
+ return Fields;
+ }
+
// Unnamed bitfields are only used for padding and do not appear in
// `InitListExpr`'s inits. However, those fields do appear in `RecordDecl`'s
// field list, and we thus need to remove them before mapping inits to
// fields to avoid mapping inits to the wrongs fields.
- std::vector<FieldDecl *> Fields;
llvm::copy_if(
RD->fields(), std::back_inserter(Fields),
[](const FieldDecl *Field) { return !Field->isUnnamedBitfield(); });
diff --git a/clang/lib/Analysis/FlowSensitive/Transfer.cpp b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
index fe13e919bddcd8..e793e8fb593dc3 100644
--- a/clang/lib/Analysis/FlowSensitive/Transfer.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
@@ -663,14 +663,7 @@ class TransferVisitor : public ConstStmtVisitor<TransferVisitor> {
void VisitInitListExpr(const InitListExpr *S) {
QualType Type = S->getType();
- if (Type->isUnionType()) {
- // FIXME: Initialize unions properly.
- if (auto *Val = Env.createValue(Type))
- Env.setValue(*S, *Val);
- return;
- }
-
- if (!Type->isStructureOrClassType()) {
+ if (!Type->isRecordType()) {
// Until array initialization is implemented, we don't need to care about
// cases where `getNumInits() > 1`.
if (S->getNumInits() == 1)
@@ -688,10 +681,9 @@ class TransferVisitor : public ConstStmtVisitor<TransferVisitor> {
llvm::DenseMap<const ValueDecl *, StorageLocation *> FieldLocs;
// This only contains the direct fields for the given type.
- std::vector<FieldDecl *> FieldsForInit =
- getFieldsForInitListExpr(Type->getAsRecordDecl());
+ std::vector<const FieldDecl *> FieldsForInit = getFieldsForInitListExpr(S);
- // `S->inits()` contains all the initializer epressions, including the
+ // `S->inits()` contains all the initializer expressions, including the
// ones for direct base classes.
auto Inits = S->inits();
size_t InitIdx = 0;
@@ -731,6 +723,18 @@ class TransferVisitor : public ConstStmtVisitor<TransferVisitor> {
FieldLocs.insert({Field, &Loc});
}
+ // In the case of a union, we don't in general have initializers for all
+ // of the fields. Create storage locations for the remaining fields (but
+ // don't associate them with values).
+ if (Type->isUnionType()) {
+ for (const FieldDecl *Field :
+ Env.getDataflowAnalysisContext().getModeledFields(Type)) {
+ if (!FieldLocs.contains(Field))
+ FieldLocs.insert(
+ {Field, &Env.createStorageLocation(Field->getType())});
+ }
+ }
+
// Check that we satisfy the invariant that a `RecordStorageLoation`
// contains exactly the set of modeled fields for that type.
// `ModeledFields` includes fields from all the bases, but only the
diff --git a/clang/unittests/Analysis/FlowSensitive/TestingSupport.h b/clang/unittests/Analysis/FlowSensitive/TestingSupport.h
index 0d36d2802897fd..b7cf6cc966edb0 100644
--- a/clang/unittests/Analysis/FlowSensitive/TestingSupport.h
+++ b/clang/unittests/Analysis/FlowSensitive/TestingSupport.h
@@ -432,6 +432,8 @@ llvm::Error checkDataflowWithNoopAnalysis(
{});
/// Returns the `ValueDecl` for the given identifier.
+/// The returned pointer is guaranteed to be non-null; the function asserts if
+/// no `ValueDecl` with the given name is found.
///
/// Requirements:
///
@@ -475,6 +477,15 @@ ValueT &getValueForDecl(ASTContext &ASTCtx, const Environment &Env,
return *cast<ValueT>(Env.getValue(*VD));
}
+/// Returns the storage location for the field called `Name` of `Loc`.
+/// Optionally casts the field storage location to `T`.
+template <typename T = StorageLocation>
+std::enable_if_t<std::is_base_of_v<StorageLocation, T>, T &>
+getFieldLoc(const RecordStorageLocation &Loc, llvm::StringRef Name,
+ ASTContext &ASTCtx) {
+ return *cast<T>(Loc.getChild(*findValueDecl(ASTCtx, Name)));
+}
+
/// Returns the value of a `Field` on the record referenced by `Loc.`
/// Returns null if `Loc` is null.
inline Value *getFieldValue(const RecordStorageLocation *Loc,
@@ -487,6 +498,14 @@ inline Value *getFieldValue(const RecordStorageLocation *Loc,
return Env.getValue(*FieldLoc);
}
+/// Returns the value of a `Field` on the record referenced by `Loc.`
+/// Returns null if `Loc` is null.
+inline Value *getFieldValue(const RecordStorageLocation *Loc,
+ llvm::StringRef Name, ASTContext &ASTCtx,
+ const Environment &Env) {
+ return getFieldValue(Loc, *findValueDecl(ASTCtx, Name), Env);
+}
+
/// Creates and owns constraints which are boolean values.
class ConstraintContext {
unsigned NextAtom = 0;
diff --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
index a65b0446ac7818..e7d74581865a32 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -2377,14 +2377,24 @@ TEST(TransferTest, InitListExprAsUnion) {
} F;
public:
- constexpr target() : F{nullptr} {}
+ constexpr target() : F{nullptr} {
+ int *null = nullptr;
+ F.b; // Make sure we reference 'b' so it is modeled.
+ // [[p]]
+ }
};
)cc";
runDataflow(
Code,
[](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
ASTContext &ASTCtx) {
- // Just verify that it doesn't crash.
+ const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+
+ auto &FLoc = getFieldLoc<RecordStorageLocation>(
+ *Env.getThisPointeeStorageLocation(), "F", ASTCtx);
+ auto *AVal = cast<PointerValue>(getFieldValue(&FLoc, "a", ASTCtx, Env));
+ ASSERT_EQ(AVal, &getValueForDecl<PointerValue>(ASTCtx, Env, "null"));
+ ASSERT_EQ(getFieldValue(&FLoc, "b", ASTCtx, Env), nullptr);
});
}
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