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//===- ThreadSafetyCommon.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
//
//===----------------------------------------------------------------------===//
//
// Parts of thread safety analysis that are not specific to thread safety
// itself have been factored into classes here, where they can be potentially
// used by other analyses. Currently these include:
//
// * Generalize clang CFG visitors.
// * Conversion of the clang CFG to SSA form.
// * Translation of clang Exprs to TIL SExprs
//
// UNDER CONSTRUCTION. USE AT YOUR OWN RISK.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYCOMMON_H
#define LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYCOMMON_H
#include "clang/AST/Decl.h"
#include "clang/Analysis/Analyses/PostOrderCFGView.h"
#include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
#include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
#include "clang/Analysis/Analyses/ThreadSafetyUtil.h"
#include "clang/Analysis/AnalysisDeclContext.h"
#include "clang/Analysis/CFG.h"
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Casting.h"
#include <sstream>
#include <string>
#include <utility>
#include <vector>
namespace clang {
class AbstractConditionalOperator;
class ArraySubscriptExpr;
class BinaryOperator;
class CallExpr;
class CastExpr;
class CXXDestructorDecl;
class CXXMemberCallExpr;
class CXXOperatorCallExpr;
class CXXThisExpr;
class DeclRefExpr;
class DeclStmt;
class Expr;
class MemberExpr;
class Stmt;
class UnaryOperator;
namespace threadSafety {
// Various helper functions on til::SExpr
namespace sx {
inline bool equals(const til::SExpr *E1, const til::SExpr *E2) {
return til::EqualsComparator::compareExprs(E1, E2);
}
inline bool matches(const til::SExpr *E1, const til::SExpr *E2) {
// We treat a top-level wildcard as the "univsersal" lock.
// It matches everything for the purpose of checking locks, but not
// for unlocking them.
if (isa<til::Wildcard>(E1))
return isa<til::Wildcard>(E2);
if (isa<til::Wildcard>(E2))
return isa<til::Wildcard>(E1);
return til::MatchComparator::compareExprs(E1, E2);
}
inline bool partiallyMatches(const til::SExpr *E1, const til::SExpr *E2) {
const auto *PE1 = dyn_cast_or_null<til::Project>(E1);
if (!PE1)
return false;
const auto *PE2 = dyn_cast_or_null<til::Project>(E2);
if (!PE2)
return false;
return PE1->clangDecl() == PE2->clangDecl();
}
inline std::string toString(const til::SExpr *E) {
std::stringstream ss;
til::StdPrinter::print(E, ss);
return ss.str();
}
} // namespace sx
// This class defines the interface of a clang CFG Visitor.
// CFGWalker will invoke the following methods.
// Note that methods are not virtual; the visitor is templatized.
class CFGVisitor {
// Enter the CFG for Decl D, and perform any initial setup operations.
void enterCFG(CFG *Cfg, const NamedDecl *D, const CFGBlock *First) {}
// Enter a CFGBlock.
void enterCFGBlock(const CFGBlock *B) {}
// Returns true if this visitor implements handlePredecessor
bool visitPredecessors() { return true; }
// Process a predecessor edge.
void handlePredecessor(const CFGBlock *Pred) {}
// Process a successor back edge to a previously visited block.
void handlePredecessorBackEdge(const CFGBlock *Pred) {}
// Called just before processing statements.
void enterCFGBlockBody(const CFGBlock *B) {}
// Process an ordinary statement.
void handleStatement(const Stmt *S) {}
// Process a destructor call
void handleDestructorCall(const VarDecl *VD, const CXXDestructorDecl *DD) {}
// Called after all statements have been handled.
void exitCFGBlockBody(const CFGBlock *B) {}
// Return true
bool visitSuccessors() { return true; }
// Process a successor edge.
void handleSuccessor(const CFGBlock *Succ) {}
// Process a successor back edge to a previously visited block.
void handleSuccessorBackEdge(const CFGBlock *Succ) {}
// Leave a CFGBlock.
void exitCFGBlock(const CFGBlock *B) {}
// Leave the CFG, and perform any final cleanup operations.
void exitCFG(const CFGBlock *Last) {}
};
// Walks the clang CFG, and invokes methods on a given CFGVisitor.
class CFGWalker {
public:
CFGWalker() = default;
// Initialize the CFGWalker. This setup only needs to be done once, even
// if there are multiple passes over the CFG.
bool init(AnalysisDeclContext &AC) {
ACtx = &AC;
CFGraph = AC.getCFG();
if (!CFGraph)
return false;
// Ignore anonymous functions.
if (!isa_and_nonnull<NamedDecl>(AC.getDecl()))
return false;
SortedGraph = AC.getAnalysis<PostOrderCFGView>();
if (!SortedGraph)
return false;
return true;
}
// Traverse the CFG, calling methods on V as appropriate.
template <class Visitor>
void walk(Visitor &V) {
PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
V.enterCFG(CFGraph, getDecl(), &CFGraph->getEntry());
for (const auto *CurrBlock : *SortedGraph) {
VisitedBlocks.insert(CurrBlock);
V.enterCFGBlock(CurrBlock);
// Process predecessors, handling back edges last
if (V.visitPredecessors()) {
SmallVector<CFGBlock*, 4> BackEdges;
// Process successors
for (CFGBlock::const_pred_iterator SI = CurrBlock->pred_begin(),
SE = CurrBlock->pred_end();
SI != SE; ++SI) {
if (*SI == nullptr)
continue;
if (!VisitedBlocks.alreadySet(*SI)) {
BackEdges.push_back(*SI);
continue;
}
V.handlePredecessor(*SI);
}
for (auto *Blk : BackEdges)
V.handlePredecessorBackEdge(Blk);
}
V.enterCFGBlockBody(CurrBlock);
// Process statements
for (const auto &BI : *CurrBlock) {
switch (BI.getKind()) {
case CFGElement::Statement:
V.handleStatement(BI.castAs<CFGStmt>().getStmt());
break;
case CFGElement::AutomaticObjectDtor: {
CFGAutomaticObjDtor AD = BI.castAs<CFGAutomaticObjDtor>();
auto *DD = const_cast<CXXDestructorDecl *>(
AD.getDestructorDecl(ACtx->getASTContext()));
auto *VD = const_cast<VarDecl *>(AD.getVarDecl());
V.handleDestructorCall(VD, DD);
break;
}
default:
break;
}
}
V.exitCFGBlockBody(CurrBlock);
// Process successors, handling back edges first.
if (V.visitSuccessors()) {
SmallVector<CFGBlock*, 8> ForwardEdges;
// Process successors
for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
SE = CurrBlock->succ_end();
SI != SE; ++SI) {
if (*SI == nullptr)
continue;
if (!VisitedBlocks.alreadySet(*SI)) {
ForwardEdges.push_back(*SI);
continue;
}
V.handleSuccessorBackEdge(*SI);
}
for (auto *Blk : ForwardEdges)
V.handleSuccessor(Blk);
}
V.exitCFGBlock(CurrBlock);
}
V.exitCFG(&CFGraph->getExit());
}
const CFG *getGraph() const { return CFGraph; }
CFG *getGraph() { return CFGraph; }
const NamedDecl *getDecl() const {
return dyn_cast<NamedDecl>(ACtx->getDecl());
}
const PostOrderCFGView *getSortedGraph() const { return SortedGraph; }
private:
CFG *CFGraph = nullptr;
AnalysisDeclContext *ACtx = nullptr;
PostOrderCFGView *SortedGraph = nullptr;
};
// TODO: move this back into ThreadSafety.cpp
// This is specific to thread safety. It is here because
// translateAttrExpr needs it, but that should be moved too.
class CapabilityExpr {
private:
/// The capability expression and whether it's negated.
llvm::PointerIntPair<const til::SExpr *, 1, bool> CapExpr;
/// The kind of capability as specified by @ref CapabilityAttr::getName.
StringRef CapKind;
public:
CapabilityExpr() : CapExpr(nullptr, false) {}
CapabilityExpr(const til::SExpr *E, StringRef Kind, bool Neg)
: CapExpr(E, Neg), CapKind(Kind) {}
// Don't allow implicitly-constructed StringRefs since we'll capture them.
template <typename T> CapabilityExpr(const til::SExpr *, T, bool) = delete;
const til::SExpr *sexpr() const { return CapExpr.getPointer(); }
StringRef getKind() const { return CapKind; }
bool negative() const { return CapExpr.getInt(); }
CapabilityExpr operator!() const {
return CapabilityExpr(CapExpr.getPointer(), CapKind, !CapExpr.getInt());
}
bool equals(const CapabilityExpr &other) const {
return (negative() == other.negative()) &&
sx::equals(sexpr(), other.sexpr());
}
bool matches(const CapabilityExpr &other) const {
return (negative() == other.negative()) &&
sx::matches(sexpr(), other.sexpr());
}
bool matchesUniv(const CapabilityExpr &CapE) const {
return isUniversal() || matches(CapE);
}
bool partiallyMatches(const CapabilityExpr &other) const {
return (negative() == other.negative()) &&
sx::partiallyMatches(sexpr(), other.sexpr());
}
const ValueDecl* valueDecl() const {
if (negative() || sexpr() == nullptr)
return nullptr;
if (const auto *P = dyn_cast<til::Project>(sexpr()))
return P->clangDecl();
if (const auto *P = dyn_cast<til::LiteralPtr>(sexpr()))
return P->clangDecl();
return nullptr;
}
std::string toString() const {
if (negative())
return "!" + sx::toString(sexpr());
return sx::toString(sexpr());
}
bool shouldIgnore() const { return sexpr() == nullptr; }
bool isInvalid() const { return isa_and_nonnull<til::Undefined>(sexpr()); }
bool isUniversal() const { return isa_and_nonnull<til::Wildcard>(sexpr()); }
};
// Translate clang::Expr to til::SExpr.
class SExprBuilder {
public:
/// Encapsulates the lexical context of a function call. The lexical
/// context includes the arguments to the call, including the implicit object
/// argument. When an attribute containing a mutex expression is attached to
/// a method, the expression may refer to formal parameters of the method.
/// Actual arguments must be substituted for formal parameters to derive
/// the appropriate mutex expression in the lexical context where the function
/// is called. PrevCtx holds the context in which the arguments themselves
/// should be evaluated; multiple calling contexts can be chained together
/// by the lock_returned attribute.
struct CallingContext {
// The previous context; or 0 if none.
CallingContext *Prev;
// The decl to which the attr is attached.
const NamedDecl *AttrDecl;
// Implicit object argument -- e.g. 'this'
llvm::PointerUnion<const Expr *, til::SExpr *> SelfArg = nullptr;
// Number of funArgs
unsigned NumArgs = 0;
// Function arguments
llvm::PointerUnion<const Expr *const *, til::SExpr *> FunArgs = nullptr;
// is Self referred to with -> or .?
bool SelfArrow = false;
CallingContext(CallingContext *P, const NamedDecl *D = nullptr)
: Prev(P), AttrDecl(D) {}
};
SExprBuilder(til::MemRegionRef A) : Arena(A) {
// FIXME: we don't always have a self-variable.
SelfVar = new (Arena) til::Variable(nullptr);
SelfVar->setKind(til::Variable::VK_SFun);
}
// Translate a clang expression in an attribute to a til::SExpr.
// Constructs the context from D, DeclExp, and SelfDecl.
CapabilityExpr translateAttrExpr(const Expr *AttrExp, const NamedDecl *D,
const Expr *DeclExp,
til::SExpr *Self = nullptr);
CapabilityExpr translateAttrExpr(const Expr *AttrExp, CallingContext *Ctx);
// Translate a variable reference.
til::LiteralPtr *createVariable(const VarDecl *VD);
// Create placeholder for this: we don't know the VarDecl on construction yet.
std::pair<til::LiteralPtr *, StringRef>
createThisPlaceholder(const Expr *Exp);
// Translate a clang statement or expression to a TIL expression.
// Also performs substitution of variables; Ctx provides the context.
// Dispatches on the type of S.
til::SExpr *translate(const Stmt *S, CallingContext *Ctx);
til::SCFG *buildCFG(CFGWalker &Walker);
til::SExpr *lookupStmt(const Stmt *S);
til::BasicBlock *lookupBlock(const CFGBlock *B) {
return BlockMap[B->getBlockID()];
}
const til::SCFG *getCFG() const { return Scfg; }
til::SCFG *getCFG() { return Scfg; }
private:
// We implement the CFGVisitor API
friend class CFGWalker;
til::SExpr *translateDeclRefExpr(const DeclRefExpr *DRE,
CallingContext *Ctx) ;
til::SExpr *translateCXXThisExpr(const CXXThisExpr *TE, CallingContext *Ctx);
til::SExpr *translateMemberExpr(const MemberExpr *ME, CallingContext *Ctx);
til::SExpr *translateObjCIVarRefExpr(const ObjCIvarRefExpr *IVRE,
CallingContext *Ctx);
til::SExpr *translateCallExpr(const CallExpr *CE, CallingContext *Ctx,
const Expr *SelfE = nullptr);
til::SExpr *translateCXXMemberCallExpr(const CXXMemberCallExpr *ME,
CallingContext *Ctx);
til::SExpr *translateCXXOperatorCallExpr(const CXXOperatorCallExpr *OCE,
CallingContext *Ctx);
til::SExpr *translateUnaryOperator(const UnaryOperator *UO,
CallingContext *Ctx);
til::SExpr *translateBinOp(til::TIL_BinaryOpcode Op,
const BinaryOperator *BO,
CallingContext *Ctx, bool Reverse = false);
til::SExpr *translateBinAssign(til::TIL_BinaryOpcode Op,
const BinaryOperator *BO,
CallingContext *Ctx, bool Assign = false);
til::SExpr *translateBinaryOperator(const BinaryOperator *BO,
CallingContext *Ctx);
til::SExpr *translateCastExpr(const CastExpr *CE, CallingContext *Ctx);
til::SExpr *translateArraySubscriptExpr(const ArraySubscriptExpr *E,
CallingContext *Ctx);
til::SExpr *translateAbstractConditionalOperator(
const AbstractConditionalOperator *C, CallingContext *Ctx);
til::SExpr *translateDeclStmt(const DeclStmt *S, CallingContext *Ctx);
// Map from statements in the clang CFG to SExprs in the til::SCFG.
using StatementMap = llvm::DenseMap<const Stmt *, til::SExpr *>;
// Map from clang local variables to indices in a LVarDefinitionMap.
using LVarIndexMap = llvm::DenseMap<const ValueDecl *, unsigned>;
// Map from local variable indices to SSA variables (or constants).
using NameVarPair = std::pair<const ValueDecl *, til::SExpr *>;
using LVarDefinitionMap = CopyOnWriteVector<NameVarPair>;
struct BlockInfo {
LVarDefinitionMap ExitMap;
bool HasBackEdges = false;
// Successors yet to be processed
unsigned UnprocessedSuccessors = 0;
// Predecessors already processed
unsigned ProcessedPredecessors = 0;
BlockInfo() = default;
BlockInfo(BlockInfo &&) = default;
BlockInfo &operator=(BlockInfo &&) = default;
};
void enterCFG(CFG *Cfg, const NamedDecl *D, const CFGBlock *First);
void enterCFGBlock(const CFGBlock *B);
bool visitPredecessors() { return true; }
void handlePredecessor(const CFGBlock *Pred);
void handlePredecessorBackEdge(const CFGBlock *Pred);
void enterCFGBlockBody(const CFGBlock *B);
void handleStatement(const Stmt *S);
void handleDestructorCall(const VarDecl *VD, const CXXDestructorDecl *DD);
void exitCFGBlockBody(const CFGBlock *B);
bool visitSuccessors() { return true; }
void handleSuccessor(const CFGBlock *Succ);
void handleSuccessorBackEdge(const CFGBlock *Succ);
void exitCFGBlock(const CFGBlock *B);
void exitCFG(const CFGBlock *Last);
void insertStmt(const Stmt *S, til::SExpr *E) {
SMap.insert(std::make_pair(S, E));
}
til::SExpr *addStatement(til::SExpr *E, const Stmt *S,
const ValueDecl *VD = nullptr);
til::SExpr *lookupVarDecl(const ValueDecl *VD);
til::SExpr *addVarDecl(const ValueDecl *VD, til::SExpr *E);
til::SExpr *updateVarDecl(const ValueDecl *VD, til::SExpr *E);
void makePhiNodeVar(unsigned i, unsigned NPreds, til::SExpr *E);
void mergeEntryMap(LVarDefinitionMap Map);
void mergeEntryMapBackEdge();
void mergePhiNodesBackEdge(const CFGBlock *Blk);
private:
// Set to true when parsing capability expressions, which get translated
// inaccurately in order to hack around smart pointers etc.
static const bool CapabilityExprMode = true;
til::MemRegionRef Arena;
// Variable to use for 'this'. May be null.
til::Variable *SelfVar = nullptr;
til::SCFG *Scfg = nullptr;
// Map from Stmt to TIL Variables
StatementMap SMap;
// Indices of clang local vars.
LVarIndexMap LVarIdxMap;
// Map from clang to til BBs.
std::vector<til::BasicBlock *> BlockMap;
// Extra information per BB. Indexed by clang BlockID.
std::vector<BlockInfo> BBInfo;
LVarDefinitionMap CurrentLVarMap;
std::vector<til::Phi *> CurrentArguments;
std::vector<til::SExpr *> CurrentInstructions;
std::vector<til::Phi *> IncompleteArgs;
til::BasicBlock *CurrentBB = nullptr;
BlockInfo *CurrentBlockInfo = nullptr;
};
#ifndef NDEBUG
// Dump an SCFG to llvm::errs().
void printSCFG(CFGWalker &Walker);
#endif // NDEBUG
} // namespace threadSafety
} // namespace clang
#endif // LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYCOMMON_H
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