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[Analyzer] Support bodyfarming libstdc++ implementation of std::call_once. 

Differential Revision: https://reviews.llvm.org/D38810

llvm-svn: 315508
This commit is contained in:
George Karpenkov 2017-10-11 20:53:01 +00:00
parent 450ae592b4
commit c928e1f595
2 changed files with 35 additions and 20 deletions
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44
clang/lib/Analysis/BodyFarm.cpp
View File

@ -108,7 +108,7 @@ public:
/// Returns a *first* member field of a record declaration with a given name.
/// \return an nullptr if no member with such a name exists.
NamedDecl *findMemberField(const CXXRecordDecl *RD, StringRef Name);
ValueDecl *findMemberField(const RecordDecl *RD, StringRef Name);
private:
ASTContext &C;
@ -234,7 +234,7 @@ MemberExpr *ASTMaker::makeMemberExpression(Expr *base, ValueDecl *MemberDecl,
OK_Ordinary);
}
NamedDecl *ASTMaker::findMemberField(const CXXRecordDecl *RD, StringRef Name) {
ValueDecl *ASTMaker::findMemberField(const RecordDecl *RD, StringRef Name) {
CXXBasePaths Paths(
/* FindAmbiguities=*/false,
@ -246,7 +246,7 @@ NamedDecl *ASTMaker::findMemberField(const CXXRecordDecl *RD, StringRef Name) {
DeclContextLookupResult Decls = RD->lookup(DeclName);
for (NamedDecl *FoundDecl : Decls)
if (!FoundDecl->getDeclContext()->isFunctionOrMethod())
return FoundDecl;
return cast<ValueDecl>(FoundDecl);
return nullptr;
}
@ -328,25 +328,31 @@ static Stmt *create_call_once(ASTContext &C, const FunctionDecl *D) {
const ParmVarDecl *Callback = D->getParamDecl(1);
QualType CallbackType = Callback->getType().getNonReferenceType();
QualType FlagType = Flag->getType().getNonReferenceType();
CXXRecordDecl *FlagCXXDecl = FlagType->getAsCXXRecordDecl();
if (!FlagCXXDecl) {
DEBUG(llvm::dbgs() << "Flag field is not a CXX record: "
<< "unknown std::call_once implementation."
<< "Ignoring the call.\n");
auto *FlagRecordDecl = dyn_cast_or_null<RecordDecl>(FlagType->getAsTagDecl());
if (!FlagRecordDecl) {
DEBUG(llvm::dbgs() << "Flag field is not a record: "
<< "unknown std::call_once implementation, "
<< "ignoring the call.\n");
return nullptr;
}
// Note: here we are assuming libc++ implementation of call_once,
// which has a struct with a field `__state_`.
// Body farming might not work for other `call_once` implementations.
NamedDecl *FoundDecl = M.findMemberField(FlagCXXDecl, "__state_");
ValueDecl *FieldDecl;
if (FoundDecl) {
FieldDecl = dyn_cast<ValueDecl>(FoundDecl);
} else {
// We initially assume libc++ implementation of call_once,
// where the once_flag struct has a field `__state_`.
ValueDecl *FlagFieldDecl = M.findMemberField(FlagRecordDecl, "__state_");
// Otherwise, try libstdc++ implementation, with a field
// `_M_once`
if (!FlagFieldDecl) {
DEBUG(llvm::dbgs() << "No field __state_ found on std::once_flag struct, "
<< "unable to synthesize call_once body, ignoring "
<< "the call.\n");
<< "assuming libstdc++ implementation\n");
FlagFieldDecl = M.findMemberField(FlagRecordDecl, "_M_once");
}
if (!FlagFieldDecl) {
DEBUG(llvm::dbgs() << "No field _M_once found on std::once flag struct: "
<< "unknown std::call_once implementation, "
<< "ignoring the call");
return nullptr;
}
@ -383,7 +389,7 @@ static Stmt *create_call_once(ASTContext &C, const FunctionDecl *D) {
/* GetNonReferenceType=*/true);
MemberExpr *Deref = M.makeMemberExpression(FlagDecl, FieldDecl);
MemberExpr *Deref = M.makeMemberExpression(FlagDecl, FlagFieldDecl);
assert(Deref->isLValue());
QualType DerefType = Deref->getType();

11
clang/test/Analysis/call_once.cpp
View File

@ -1,15 +1,24 @@
// RUN: %clang_analyze_cc1 -std=c++11 -fblocks -analyzer-checker=core,debug.ExprInspection -w -verify %s
// RUN: %clang_analyze_cc1 -std=c++11 -fblocks -analyzer-checker=core,debug.ExprInspection -verify %s
// RUN: %clang_analyze_cc1 -std=c++11 -fblocks -analyzer-checker=core,debug.ExprInspection -DEMULATE_LIBSTDCPP -verify %s
void clang_analyzer_eval(bool);
// Faking std::std::call_once implementation.
namespace std {
#ifndef EMULATE_LIBSTDCPP
typedef struct once_flag_s {
unsigned long __state_ = 0;
} once_flag;
#else
typedef struct once_flag_s {
int _M_once = 0;
} once_flag;
#endif
template <class Callable, class... Args>
void call_once(once_flag &o, Callable func, Args... args) {};
} // namespace std
// Check with Lambdas.