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850b106400
v8/tools/gcmole/gcmole.cc
vegorov@chromium.org 850b106400 Extend GCMole with poor man's data flow analysis to catch dead raw pointer vars. 
Fix various places in the code found by improved GCMole.

Review URL: http://codereview.chromium.org/6973063

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7895 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2011-05-16 09:06:16 +00:00

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// Copyright 2011 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// This is clang plugin used by gcmole tool. See README for more details.
#include "clang/AST/AST.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/Mangle.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Frontend/FrontendPluginRegistry.h"
#include "clang/Frontend/CompilerInstance.h"
#include "llvm/Support/raw_ostream.h"
#include <bitset>
#include <fstream>
#include <iostream>
#include <map>
#include <set>
#include <stack>
namespace {
typedef std::string MangledName;
typedef std::set<MangledName> CalleesSet;
static bool GetMangledName(clang::MangleContext* ctx,
const clang::NamedDecl* decl,
MangledName* result) {
if (!isa<clang::CXXConstructorDecl>(decl) &&
!isa<clang::CXXDestructorDecl>(decl)) {
llvm::SmallVector<char, 512> output;
llvm::raw_svector_ostream out(output);
ctx->mangleName(decl, out);
*result = out.str().str();
return true;
}
return false;
}
static bool InV8Namespace(const clang::NamedDecl* decl) {
return decl->getQualifiedNameAsString().compare(0, 4, "v8::") == 0;
}
struct Resolver {
explicit Resolver(clang::ASTContext& ctx)
: ctx_(ctx), decl_ctx_(ctx.getTranslationUnitDecl()) {
}
Resolver(clang::ASTContext& ctx, clang::DeclContext* decl_ctx)
: ctx_(ctx), decl_ctx_(decl_ctx) {
}
clang::DeclarationName ResolveName(const char* n) {
clang::IdentifierInfo* ident = &ctx_.Idents.get(n);
return ctx_.DeclarationNames.getIdentifier(ident);
}
Resolver ResolveNamespace(const char* n) {
return Resolver(ctx_, Resolve<clang::NamespaceDecl>(n));
}
template<typename T>
T* Resolve(const char* n) {
if (decl_ctx_ == NULL) return NULL;
clang::DeclContext::lookup_result result =
decl_ctx_->lookup(ResolveName(n));
clang::DeclContext::lookup_iterator end = result.second;
for (clang::DeclContext::lookup_iterator i = result.first;
i != end;
i++) {
if (isa<T>(*i)) return cast<T>(*i);
}
return NULL;
}
private:
clang::ASTContext& ctx_;
clang::DeclContext* decl_ctx_;
};
class CalleesPrinter : public clang::RecursiveASTVisitor<CalleesPrinter> {
public:
explicit CalleesPrinter(clang::MangleContext* ctx) : ctx_(ctx) {
}
virtual bool VisitCallExpr(clang::CallExpr* expr) {
const clang::FunctionDecl* callee = expr->getDirectCallee();
if (callee != NULL) AnalyzeFunction(callee);
return true;
}
void AnalyzeFunction(const clang::FunctionDecl* f) {
MangledName name;
if (InV8Namespace(f) && GetMangledName(ctx_, f, &name)) {
AddCallee(name);
const clang::FunctionDecl* body = NULL;
if (f->hasBody(body) && !Analyzed(name)) {
EnterScope(name);
TraverseStmt(body->getBody());
LeaveScope();
}
}
}
typedef std::map<MangledName, CalleesSet* > Callgraph;
bool Analyzed(const MangledName& name) {
return callgraph_[name] != NULL;
}
void EnterScope(const MangledName& name) {
CalleesSet* callees = callgraph_[name];
if (callees == NULL) {
callgraph_[name] = callees = new CalleesSet();
}
scopes_.push(callees);
}
void LeaveScope() {
scopes_.pop();
}
void AddCallee(const MangledName& name) {
if (!scopes_.empty()) scopes_.top()->insert(name);
}
void PrintCallGraph() {
for (Callgraph::const_iterator i = callgraph_.begin(), e = callgraph_.end();
i != e;
++i) {
std::cout << i->first << "\n";
CalleesSet* callees = i->second;
for (CalleesSet::const_iterator j = callees->begin(), e = callees->end();
j != e;
++j) {
std::cout << "\t" << *j << "\n";
}
}
}
private:
clang::MangleContext* ctx_;
std::stack<CalleesSet* > scopes_;
Callgraph callgraph_;
};
class FunctionDeclarationFinder
: public clang::ASTConsumer,
public clang::RecursiveASTVisitor<FunctionDeclarationFinder> {
public:
explicit FunctionDeclarationFinder(clang::Diagnostic& d,
clang::SourceManager& sm,
const std::vector<std::string>& args)
: d_(d), sm_(sm) { }
virtual void HandleTranslationUnit(clang::ASTContext &ctx) {
mangle_context_ = clang::createItaniumMangleContext(ctx, d_);
callees_printer_ = new CalleesPrinter(mangle_context_);
TraverseDecl(ctx.getTranslationUnitDecl());
callees_printer_->PrintCallGraph();
}
virtual bool VisitFunctionDecl(clang::FunctionDecl* decl) {
callees_printer_->AnalyzeFunction(decl);
return true;
}
private:
clang::Diagnostic& d_;
clang::SourceManager& sm_;
clang::MangleContext* mangle_context_;
CalleesPrinter* callees_printer_;
};
static bool loaded = false;
static CalleesSet gc_suspects;
static void LoadGCSuspects() {
if (loaded) return;
std::ifstream fin("gcsuspects");
std::string s;
while (fin >> s) gc_suspects.insert(s);
loaded = true;
}
static bool KnownToCauseGC(clang::MangleContext* ctx,
const clang::FunctionDecl* decl) {
LoadGCSuspects();
if (!InV8Namespace(decl)) return false;
MangledName name;
if (GetMangledName(ctx, decl, &name)) {
return gc_suspects.find(name) != gc_suspects.end();
}
return false;
}
static const int kNoEffect = 0;
static const int kCausesGC = 1;
static const int kRawDef = 2;
static const int kRawUse = 4;
static const int kAllEffects = kCausesGC | kRawDef | kRawUse;
class Environment;
class ExprEffect {
public:
bool hasGC() { return (effect_ & kCausesGC) != 0; }
void setGC() { effect_ |= kCausesGC; }
bool hasRawDef() { return (effect_ & kRawDef) != 0; }
void setRawDef() { effect_ |= kRawDef; }
bool hasRawUse() { return (effect_ & kRawUse) != 0; }
void setRawUse() { effect_ |= kRawUse; }
static ExprEffect None() { return ExprEffect(kNoEffect, NULL); }
static ExprEffect NoneWithEnv(Environment* env) {
return ExprEffect(kNoEffect, env);
}
static ExprEffect RawUse() { return ExprEffect(kRawUse, NULL); }
static ExprEffect Merge(ExprEffect a, ExprEffect b);
static ExprEffect MergeSeq(ExprEffect a, ExprEffect b);
ExprEffect Define(const std::string& name);
Environment* env() {
return reinterpret_cast<Environment*>(effect_ & ~kAllEffects);
}
private:
ExprEffect(int effect, Environment* env)
: effect_((effect & kAllEffects) |
reinterpret_cast<intptr_t>(env)) { }
intptr_t effect_;
};
const std::string BAD_EXPR_MSG("Possible problem with evaluation order.");
const std::string DEAD_VAR_MSG("Possibly dead variable.");
class Environment {
public:
Environment() { }
static Environment Unreachable() {
Environment env;
env.live_.set();
return env;
}
static Environment Merge(const Environment& l,
const Environment& r) {
return Environment(l, r);
}
Environment ApplyEffect(ExprEffect effect) const {
Environment out = effect.hasGC() ? Environment() : Environment(*this);
if (effect.env() != NULL) out.live_ |= effect.env()->live_;
return out;
}
typedef std::map<std::string, int> SymbolTable;
bool IsAlive(const std::string& name) const {
SymbolTable::iterator code = symbol_table_.find(name);
if (code == symbol_table_.end()) return false;
return live_[code->second];
}
bool Equal(const Environment& env) {
return live_ == env.live_;
}
Environment Define(const std::string& name) const {
return Environment(*this, SymbolToCode(name));
}
void MDefine(const std::string& name) {
live_.set(SymbolToCode(name));
}
static int SymbolToCode(const std::string& name) {
SymbolTable::iterator code = symbol_table_.find(name);
if (code == symbol_table_.end()) {
int new_code = symbol_table_.size();
symbol_table_.insert(std::make_pair(name, new_code));
return new_code;
}
return code->second;
}
static void ClearSymbolTable() {
std::vector<Environment*>::iterator end = envs_.end();
for (std::vector<Environment*>::iterator i = envs_.begin();
i != end;
++i) {
delete *i;
}
envs_.clear();
symbol_table_.clear();
}
void Print() const {
bool comma = false;
std::cout << "{";
SymbolTable::iterator end = symbol_table_.end();
for (SymbolTable::iterator i = symbol_table_.begin();
i != end;
++i) {
if (live_[i->second]) {
if (comma) std::cout << ", ";
std::cout << i->first;
comma = true;
}
}
std::cout << "}";
}
static Environment* Allocate(const Environment& env) {
Environment* allocated_env = new Environment(env);
envs_.push_back(allocated_env);
return allocated_env;
}
private:
Environment(const Environment& l, const Environment& r)
: live_(l.live_ & r.live_) {
}
Environment(const Environment& l, int code)
: live_(l.live_) {
live_.set(code);
}
static SymbolTable symbol_table_;
static std::vector<Environment* > envs_;
static const int kMaxNumberOfLocals = 256;
std::bitset<kMaxNumberOfLocals> live_;
friend class ExprEffect;
friend class CallProps;
};
class CallProps {
public:
CallProps() : env_(NULL) { }
void SetEffect(int arg, ExprEffect in) {
if (in.hasGC()) gc_.set(arg);
if (in.hasRawDef()) raw_def_.set(arg);
if (in.hasRawUse()) raw_use_.set(arg);
if (in.env() != NULL) {
if (env_ == NULL) env_ = in.env();
env_->live_ |= in.env()->live_;
}
}
ExprEffect ComputeCumulativeEffect(bool result_is_raw) {
ExprEffect out = ExprEffect::NoneWithEnv(env_);
if (gc_.any()) out.setGC();
if (raw_use_.any()) out.setRawUse();
if (result_is_raw) out.setRawDef();
return out;
}
bool IsSafe() {
if (!gc_.any()) return true;
std::bitset<kMaxNumberOfArguments> raw = (raw_def_ | raw_use_);
if (!raw.any()) return true;
return gc_.count() == 1 && !((raw ^ gc_).any());
}
private:
static const int kMaxNumberOfArguments = 64;
std::bitset<kMaxNumberOfArguments> raw_def_;
std::bitset<kMaxNumberOfArguments> raw_use_;
std::bitset<kMaxNumberOfArguments> gc_;
Environment* env_;
};
Environment::SymbolTable Environment::symbol_table_;
std::vector<Environment* > Environment::envs_;
ExprEffect ExprEffect::Merge(ExprEffect a, ExprEffect b) {
Environment* a_env = a.env();
Environment* b_env = b.env();
Environment* out = NULL;
if (a_env != NULL && b_env != NULL) {
out = Environment::Allocate(*a_env);
out->live_ &= b_env->live_;
}
return ExprEffect(a.effect_ | b.effect_, out);
}
ExprEffect ExprEffect::MergeSeq(ExprEffect a, ExprEffect b) {
Environment* a_env = b.hasGC() ? NULL : a.env();
Environment* b_env = b.env();
Environment* out = (b_env == NULL) ? a_env : b_env;
if (a_env != NULL && b_env != NULL) {
out = Environment::Allocate(*b_env);
out->live_ |= a_env->live_;
}
return ExprEffect(a.effect_ | b.effect_, out);
}
ExprEffect ExprEffect::Define(const std::string& name) {
Environment* e = env();
if (e == NULL) {
e = Environment::Allocate(Environment());
}
e->MDefine(name);
return ExprEffect(effect_, e);
}
static std::string THIS ("this");
class FunctionAnalyzer {
public:
FunctionAnalyzer(clang::MangleContext* ctx,
clang::DeclarationName handle_decl_name,
clang::CXXRecordDecl* object_decl,
clang::CXXRecordDecl* smi_decl,
clang::Diagnostic& d,
clang::SourceManager& sm,
bool dead_vars_analysis)
: ctx_(ctx),
handle_decl_name_(handle_decl_name),
object_decl_(object_decl),
smi_decl_(smi_decl),
d_(d),
sm_(sm),
block_(NULL),
dead_vars_analysis_(dead_vars_analysis) {
}
// --------------------------------------------------------------------------
// Expressions
// --------------------------------------------------------------------------
ExprEffect VisitExpr(clang::Expr* expr, const Environment& env) {
#define VISIT(type) do { \
clang::type* concrete_expr = dyn_cast_or_null<clang::type>(expr); \
if (concrete_expr != NULL) { \
return Visit##type (concrete_expr, env); \
} \
} while(0);
VISIT(AbstractConditionalOperator);
VISIT(AddrLabelExpr);
VISIT(ArraySubscriptExpr);
VISIT(BinaryOperator);
VISIT(BinaryTypeTraitExpr);
VISIT(BlockDeclRefExpr);
VISIT(BlockExpr);
VISIT(CallExpr);
VISIT(CastExpr);
VISIT(CharacterLiteral);
VISIT(ChooseExpr);
VISIT(CompoundLiteralExpr);
VISIT(CXXBindTemporaryExpr);
VISIT(CXXBoolLiteralExpr);
VISIT(CXXConstructExpr);
VISIT(CXXDefaultArgExpr);
VISIT(CXXDeleteExpr);
VISIT(CXXDependentScopeMemberExpr);
VISIT(CXXNewExpr);
VISIT(CXXNoexceptExpr);
VISIT(CXXNullPtrLiteralExpr);
VISIT(CXXPseudoDestructorExpr);
VISIT(CXXScalarValueInitExpr);
VISIT(CXXThisExpr);
VISIT(CXXThrowExpr);
VISIT(CXXTypeidExpr);
VISIT(CXXUnresolvedConstructExpr);
VISIT(CXXUuidofExpr);
VISIT(DeclRefExpr);
VISIT(DependentScopeDeclRefExpr);
VISIT(DesignatedInitExpr);
VISIT(ExprWithCleanups);
VISIT(ExtVectorElementExpr);
VISIT(FloatingLiteral);
VISIT(GNUNullExpr);
VISIT(ImaginaryLiteral);
VISIT(ImplicitValueInitExpr);
VISIT(InitListExpr);
VISIT(IntegerLiteral);
VISIT(MemberExpr);
VISIT(OffsetOfExpr);
VISIT(OpaqueValueExpr);
VISIT(OverloadExpr);
VISIT(PackExpansionExpr);
VISIT(ParenExpr);
VISIT(ParenListExpr);
VISIT(PredefinedExpr);
VISIT(ShuffleVectorExpr);
VISIT(SizeOfPackExpr);
VISIT(StmtExpr);
VISIT(StringLiteral);
VISIT(SubstNonTypeTemplateParmPackExpr);
VISIT(UnaryExprOrTypeTraitExpr);
VISIT(UnaryOperator);
VISIT(UnaryTypeTraitExpr);
VISIT(VAArgExpr);
#undef VISIT
return ExprEffect::None();
}
#define DECL_VISIT_EXPR(type) \
ExprEffect Visit##type (clang::type* expr, const Environment& env)
#define IGNORE_EXPR(type) \
ExprEffect Visit##type (clang::type* expr, const Environment& env) { \
return ExprEffect::None(); \
}
IGNORE_EXPR(AddrLabelExpr);
IGNORE_EXPR(BinaryTypeTraitExpr);
IGNORE_EXPR(BlockExpr);
IGNORE_EXPR(CharacterLiteral);
IGNORE_EXPR(ChooseExpr);
IGNORE_EXPR(CompoundLiteralExpr);
IGNORE_EXPR(CXXBoolLiteralExpr);
IGNORE_EXPR(CXXDependentScopeMemberExpr);
IGNORE_EXPR(CXXNullPtrLiteralExpr);
IGNORE_EXPR(CXXPseudoDestructorExpr);
IGNORE_EXPR(CXXScalarValueInitExpr);
IGNORE_EXPR(CXXNoexceptExpr);
IGNORE_EXPR(CXXTypeidExpr);
IGNORE_EXPR(CXXUnresolvedConstructExpr);
IGNORE_EXPR(CXXUuidofExpr);
IGNORE_EXPR(DependentScopeDeclRefExpr);
IGNORE_EXPR(DesignatedInitExpr);
IGNORE_EXPR(ExtVectorElementExpr);
IGNORE_EXPR(FloatingLiteral);
IGNORE_EXPR(ImaginaryLiteral);
IGNORE_EXPR(IntegerLiteral);
IGNORE_EXPR(OffsetOfExpr);
IGNORE_EXPR(ImplicitValueInitExpr);
IGNORE_EXPR(PackExpansionExpr);
IGNORE_EXPR(PredefinedExpr);
IGNORE_EXPR(ShuffleVectorExpr);
IGNORE_EXPR(SizeOfPackExpr);
IGNORE_EXPR(StmtExpr);
IGNORE_EXPR(StringLiteral);
IGNORE_EXPR(SubstNonTypeTemplateParmPackExpr);
IGNORE_EXPR(UnaryExprOrTypeTraitExpr);
IGNORE_EXPR(UnaryTypeTraitExpr);
IGNORE_EXPR(VAArgExpr);
IGNORE_EXPR(GNUNullExpr);
IGNORE_EXPR(OverloadExpr);
DECL_VISIT_EXPR(CXXThisExpr) {
return Use(expr, expr->getType(), THIS, env);
}
DECL_VISIT_EXPR(AbstractConditionalOperator) {
Environment after_cond = env.ApplyEffect(VisitExpr(expr->getCond(), env));
return ExprEffect::Merge(VisitExpr(expr->getTrueExpr(), after_cond),
VisitExpr(expr->getFalseExpr(), after_cond));
}
DECL_VISIT_EXPR(ArraySubscriptExpr) {
clang::Expr* exprs[2] = {expr->getBase(), expr->getIdx()};
return Par(expr, 2, exprs, env);
}
bool IsRawPointerVar(clang::Expr* expr, std::string* var_name) {
if (isa<clang::BlockDeclRefExpr>(expr)) {
*var_name = cast<clang::BlockDeclRefExpr>(expr)->getDecl()->
getNameAsString();
return true;
} else if (isa<clang::DeclRefExpr>(expr)) {
*var_name = cast<clang::DeclRefExpr>(expr)->getDecl()->getNameAsString();
return true;
}
return false;
}
DECL_VISIT_EXPR(BinaryOperator) {
clang::Expr* lhs = expr->getLHS();
clang::Expr* rhs = expr->getRHS();
clang::Expr* exprs[2] = {lhs, rhs};
switch (expr->getOpcode()) {
case clang::BO_Comma:
return Seq(expr, 2, exprs, env);
case clang::BO_LAnd:
case clang::BO_LOr:
return ExprEffect::Merge(VisitExpr(lhs, env), VisitExpr(rhs, env));
case clang::BO_Assign: {
std::string var_name;
if (IsRawPointerVar(lhs, &var_name)) {
return VisitExpr(rhs, env).Define(var_name);
}
return Par(expr, 2, exprs, env);
}
default:
return Par(expr, 2, exprs, env);
}
}
DECL_VISIT_EXPR(CXXBindTemporaryExpr) {
return VisitExpr(expr->getSubExpr(), env);
}
DECL_VISIT_EXPR(CXXConstructExpr) {
return VisitArguments<>(expr, env);
}
DECL_VISIT_EXPR(CXXDefaultArgExpr) {
return VisitExpr(expr->getExpr(), env);
}
DECL_VISIT_EXPR(CXXDeleteExpr) {
return VisitExpr(expr->getArgument(), env);
}
DECL_VISIT_EXPR(CXXNewExpr) {
return Par(expr,
expr->getNumConstructorArgs(),
expr->getConstructorArgs(),
env);
}
DECL_VISIT_EXPR(ExprWithCleanups) {
return VisitExpr(expr->getSubExpr(), env);
}
DECL_VISIT_EXPR(CXXThrowExpr) {
return VisitExpr(expr->getSubExpr(), env);
}
DECL_VISIT_EXPR(InitListExpr) {
return Seq(expr, expr->getNumInits(), expr->getInits(), env);
}
DECL_VISIT_EXPR(MemberExpr) {
return VisitExpr(expr->getBase(), env);
}
DECL_VISIT_EXPR(OpaqueValueExpr) {
return VisitExpr(expr->getSourceExpr(), env);
}
DECL_VISIT_EXPR(ParenExpr) {
return VisitExpr(expr->getSubExpr(), env);
}
DECL_VISIT_EXPR(ParenListExpr) {
return Par(expr, expr->getNumExprs(), expr->getExprs(), env);
}
DECL_VISIT_EXPR(UnaryOperator) {
// TODO We are treating all expressions that look like &raw_pointer_var
// as definitions of raw_pointer_var. This should be changed to
// recognize less generic pattern:
//
// if (maybe_object->ToObject(&obj)) return maybe_object;
//
if (expr->getOpcode() == clang::UO_AddrOf) {
std::string var_name;
if (IsRawPointerVar(expr->getSubExpr(), &var_name)) {
return ExprEffect::None().Define(var_name);
}
}
return VisitExpr(expr->getSubExpr(), env);
}
DECL_VISIT_EXPR(CastExpr) {
return VisitExpr(expr->getSubExpr(), env);
}
DECL_VISIT_EXPR(DeclRefExpr) {
return Use(expr, expr->getDecl(), env);
}
DECL_VISIT_EXPR(BlockDeclRefExpr) {
return Use(expr, expr->getDecl(), env);
}
ExprEffect Par(clang::Expr* parent,
int n,
clang::Expr** exprs,
const Environment& env) {
CallProps props;
for (int i = 0; i < n; ++i) {
props.SetEffect(i, VisitExpr(exprs[i], env));
}
if (!props.IsSafe()) ReportUnsafe(parent, BAD_EXPR_MSG);
return props.ComputeCumulativeEffect(IsRawPointerType(parent->getType()));
}
ExprEffect Seq(clang::Stmt* parent,
int n,
clang::Expr** exprs,
const Environment& env) {
ExprEffect out = ExprEffect::None();
Environment out_env = env;
for (int i = 0; i < n; ++i) {
out = ExprEffect::MergeSeq(out, VisitExpr(exprs[i], out_env));
out_env = out_env.ApplyEffect(out);
}
return out;
}
ExprEffect Use(const clang::Expr* parent,
const clang::QualType& var_type,
const std::string& var_name,
const Environment& env) {
if (IsRawPointerType(var_type)) {
if (!env.IsAlive(var_name) && dead_vars_analysis_) {
ReportUnsafe(parent, DEAD_VAR_MSG);
}
return ExprEffect::RawUse();
}
return ExprEffect::None();
}
ExprEffect Use(const clang::Expr* parent,
const clang::ValueDecl* var,
const Environment& env) {
return Use(parent, var->getType(), var->getNameAsString(), env);
}
template<typename ExprType>
ExprEffect VisitArguments(ExprType* call, const Environment& env) {
CallProps props;
VisitArguments<>(call, &props, env);
if (!props.IsSafe()) ReportUnsafe(call, BAD_EXPR_MSG);
return props.ComputeCumulativeEffect(IsRawPointerType(call->getType()));
}
template<typename ExprType>
void VisitArguments(ExprType* call,
CallProps* props,
const Environment& env) {
for (unsigned arg = 0; arg < call->getNumArgs(); arg++) {
props->SetEffect(arg + 1, VisitExpr(call->getArg(arg), env));
}
}
ExprEffect VisitCallExpr(clang::CallExpr* call,
const Environment& env) {
CallProps props;
clang::CXXMemberCallExpr* memcall =
dyn_cast_or_null<clang::CXXMemberCallExpr>(call);
if (memcall != NULL) {
clang::Expr* receiver = memcall->getImplicitObjectArgument();
props.SetEffect(0, VisitExpr(receiver, env));
}
VisitArguments<>(call, &props, env);
if (!props.IsSafe()) ReportUnsafe(call, BAD_EXPR_MSG);
ExprEffect out =
props.ComputeCumulativeEffect(IsRawPointerType(call->getType()));
clang::FunctionDecl* callee = call->getDirectCallee();
if ((callee != NULL) && KnownToCauseGC(ctx_, callee)) {
out.setGC();
}
return out;
}
// --------------------------------------------------------------------------
// Statements
// --------------------------------------------------------------------------
Environment VisitStmt(clang::Stmt* stmt, const Environment& env) {
#define VISIT(type) do { \
clang::type* concrete_stmt = dyn_cast_or_null<clang::type>(stmt); \
if (concrete_stmt != NULL) { \
return Visit##type (concrete_stmt, env); \
} \
} while(0);
if (clang::Expr* expr = dyn_cast_or_null<clang::Expr>(stmt)) {
return env.ApplyEffect(VisitExpr(expr, env));
}
VISIT(AsmStmt);
VISIT(BreakStmt);
VISIT(CompoundStmt);
VISIT(ContinueStmt);
VISIT(CXXCatchStmt);
VISIT(CXXTryStmt);
VISIT(DeclStmt);
VISIT(DoStmt);
VISIT(ForStmt);
VISIT(GotoStmt);
VISIT(IfStmt);
VISIT(IndirectGotoStmt);
VISIT(LabelStmt);
VISIT(NullStmt);
VISIT(ReturnStmt);
VISIT(CaseStmt);
VISIT(DefaultStmt);
VISIT(SwitchStmt);
VISIT(WhileStmt);
#undef VISIT
return env;
}
#define DECL_VISIT_STMT(type) \
Environment Visit##type (clang::type* stmt, const Environment& env)
#define IGNORE_STMT(type) \
Environment Visit##type (clang::type* stmt, const Environment& env) { \
return env; \
}
IGNORE_STMT(IndirectGotoStmt);
IGNORE_STMT(NullStmt);
IGNORE_STMT(AsmStmt);
// We are ignoring control flow for simplicity.
IGNORE_STMT(GotoStmt);
IGNORE_STMT(LabelStmt);
// We are ignoring try/catch because V8 does not use them.
IGNORE_STMT(CXXCatchStmt);
IGNORE_STMT(CXXTryStmt);
class Block {
public:
Block(const Environment& in,
FunctionAnalyzer* owner)
: in_(in),
out_(Environment::Unreachable()),
changed_(false),
owner_(owner) {
parent_ = owner_->EnterBlock(this);
}
~Block() {
owner_->LeaveBlock(parent_);
}
void MergeIn(const Environment& env) {
Environment old_in = in_;
in_ = Environment::Merge(in_, env);
changed_ = !old_in.Equal(in_);
}
bool changed() {
if (changed_) {
changed_ = false;
return true;
}
return false;
}
const Environment& in() {
return in_;
}
const Environment& out() {
return out_;
}
void MergeOut(const Environment& env) {
out_ = Environment::Merge(out_, env);
}
void Seq(clang::Stmt* a, clang::Stmt* b, clang::Stmt* c) {
Environment a_out = owner_->VisitStmt(a, in());
Environment b_out = owner_->VisitStmt(b, a_out);
Environment c_out = owner_->VisitStmt(c, b_out);
MergeOut(c_out);
}
void Seq(clang::Stmt* a, clang::Stmt* b) {
Environment a_out = owner_->VisitStmt(a, in());
Environment b_out = owner_->VisitStmt(b, a_out);
MergeOut(b_out);
}
void Loop(clang::Stmt* a, clang::Stmt* b, clang::Stmt* c) {
Seq(a, b, c);
MergeIn(out());
}
void Loop(clang::Stmt* a, clang::Stmt* b) {
Seq(a, b);
MergeIn(out());
}
private:
Environment in_;
Environment out_;
bool changed_;
FunctionAnalyzer* owner_;
Block* parent_;
};
DECL_VISIT_STMT(BreakStmt) {
block_->MergeOut(env);
return Environment::Unreachable();
}
DECL_VISIT_STMT(ContinueStmt) {
block_->MergeIn(env);
return Environment::Unreachable();
}
DECL_VISIT_STMT(CompoundStmt) {
Environment out = env;
clang::CompoundStmt::body_iterator end = stmt->body_end();
for (clang::CompoundStmt::body_iterator s = stmt->body_begin();
s != end;
++s) {
out = VisitStmt(*s, out);
}
return out;
}
DECL_VISIT_STMT(WhileStmt) {
Block block (env, this);
do {
block.Loop(stmt->getCond(), stmt->getBody());
} while (block.changed());
return block.out();
}
DECL_VISIT_STMT(DoStmt) {
Block block (env, this);
do {
block.Loop(stmt->getBody(), stmt->getCond());
} while (block.changed());
return block.out();
}
DECL_VISIT_STMT(ForStmt) {
Block block (VisitStmt(stmt->getInit(), env), this);
do {
block.Loop(stmt->getCond(),
stmt->getBody(),
stmt->getInc());
} while (block.changed());
return block.out();
}
DECL_VISIT_STMT(IfStmt) {
Environment cond_out = VisitStmt(stmt->getCond(), env);
Environment then_out = VisitStmt(stmt->getThen(), cond_out);
Environment else_out = VisitStmt(stmt->getElse(), cond_out);
return Environment::Merge(then_out, else_out);
}
DECL_VISIT_STMT(SwitchStmt) {
Block block (env, this);
block.Seq(stmt->getCond(), stmt->getBody());
return block.out();
}
DECL_VISIT_STMT(CaseStmt) {
Environment in = Environment::Merge(env, block_->in());
Environment after_lhs = VisitStmt(stmt->getLHS(), in);
return VisitStmt(stmt->getSubStmt(), after_lhs);
}
DECL_VISIT_STMT(DefaultStmt) {
Environment in = Environment::Merge(env, block_->in());
return VisitStmt(stmt->getSubStmt(), in);
}
DECL_VISIT_STMT(ReturnStmt) {
VisitExpr(stmt->getRetValue(), env);
return Environment::Unreachable();
}
const clang::TagType* ToTagType(const clang::Type* t) {
if (t == NULL) {
return NULL;
} else if (isa<clang::TagType>(t)) {
return cast<clang::TagType>(t);
} else if (isa<clang::SubstTemplateTypeParmType>(t)) {
return ToTagType(cast<clang::SubstTemplateTypeParmType>(t)->
getReplacementType().getTypePtr());
} else {
return NULL;
}
}
bool IsDerivedFrom(clang::CXXRecordDecl* record,
clang::CXXRecordDecl* base) {
return (record == base) || record->isDerivedFrom(base);
}
bool IsRawPointerType(clang::QualType qtype) {
const clang::PointerType* type =
dyn_cast_or_null<clang::PointerType>(qtype.getTypePtrOrNull());
if (type == NULL) return false;
const clang::TagType* pointee =
ToTagType(type->getPointeeType().getTypePtr());
if (pointee == NULL) return false;
clang::CXXRecordDecl* record =
dyn_cast_or_null<clang::CXXRecordDecl>(pointee->getDecl());
if (record == NULL) return false;
if (!InV8Namespace(record)) return false;
if (!record->hasDefinition()) return false;
record = record->getDefinition();
return IsDerivedFrom(record, object_decl_) &&
!IsDerivedFrom(record, smi_decl_);
}
Environment VisitDecl(clang::Decl* decl, const Environment& env) {
if (clang::VarDecl* var = dyn_cast<clang::VarDecl>(decl)) {
Environment out = var->hasInit() ? VisitStmt(var->getInit(), env) : env;
if (IsRawPointerType(var->getType())) {
out = out.Define(var->getNameAsString());
}
return out;
}
// TODO: handle other declarations?
return env;
}
DECL_VISIT_STMT(DeclStmt) {
Environment out = env;
clang::DeclStmt::decl_iterator end = stmt->decl_end();
for (clang::DeclStmt::decl_iterator decl = stmt->decl_begin();
decl != end;
++decl) {
out = VisitDecl(*decl, out);
}
return out;
}
void DefineParameters(const clang::FunctionDecl* f,
Environment* env) {
env->MDefine(THIS);
clang::FunctionDecl::param_const_iterator end = f->param_end();
for (clang::FunctionDecl::param_const_iterator p = f->param_begin();
p != end;
++p) {
env->MDefine((*p)->getNameAsString());
}
}
void AnalyzeFunction(const clang::FunctionDecl* f) {
const clang::FunctionDecl* body = NULL;
if (f->hasBody(body)) {
Environment env;
DefineParameters(body, &env);
VisitStmt(body->getBody(), env);
Environment::ClearSymbolTable();
}
}
Block* EnterBlock(Block* block) {
Block* parent = block_;
block_ = block;
return parent;
}
void LeaveBlock(Block* block) {
block_ = block;
}
private:
void ReportUnsafe(const clang::Expr* expr, const std::string& msg) {
d_.Report(clang::FullSourceLoc(expr->getExprLoc(), sm_),
d_.getCustomDiagID(clang::Diagnostic::Warning, msg));
}
clang::MangleContext* ctx_;
clang::DeclarationName handle_decl_name_;
clang::CXXRecordDecl* object_decl_;
clang::CXXRecordDecl* smi_decl_;
clang::Diagnostic& d_;
clang::SourceManager& sm_;
Block* block_;
bool dead_vars_analysis_;
};
class ProblemsFinder : public clang::ASTConsumer,
public clang::RecursiveASTVisitor<ProblemsFinder> {
public:
ProblemsFinder(clang::Diagnostic& d,
clang::SourceManager& sm,
const std::vector<std::string>& args)
: d_(d), sm_(sm), dead_vars_analysis_(false) {
for (unsigned i = 0; i < args.size(); ++i) {
if (args[i] == "--dead-vars") {
dead_vars_analysis_ = true;
}
}
}
virtual void HandleTranslationUnit(clang::ASTContext &ctx) {
Resolver r(ctx);
clang::CXXRecordDecl* object_decl =
r.ResolveNamespace("v8").ResolveNamespace("internal").
Resolve<clang::CXXRecordDecl>("Object");
clang::CXXRecordDecl* smi_decl =
r.ResolveNamespace("v8").ResolveNamespace("internal").
Resolve<clang::CXXRecordDecl>("Smi");
if (object_decl != NULL) object_decl = object_decl->getDefinition();
if (smi_decl != NULL) smi_decl = smi_decl->getDefinition();
if (object_decl != NULL && smi_decl != NULL) {
function_analyzer_ =
new FunctionAnalyzer(clang::createItaniumMangleContext(ctx, d_),
r.ResolveName("Handle"),
object_decl,
smi_decl,
d_,
sm_,
dead_vars_analysis_);
TraverseDecl(ctx.getTranslationUnitDecl());
} else {
if (object_decl == NULL) {
llvm::errs() << "Failed to resolve v8::internal::Object\n";
}
if (smi_decl == NULL) {
llvm::errs() << "Failed to resolve v8::internal::Smi\n";
}
}
}
virtual bool VisitFunctionDecl(clang::FunctionDecl* decl) {
function_analyzer_->AnalyzeFunction(decl);
return true;
}
private:
clang::Diagnostic& d_;
clang::SourceManager& sm_;
bool dead_vars_analysis_;
FunctionAnalyzer* function_analyzer_;
};
template<typename ConsumerType>
class Action : public clang::PluginASTAction {
protected:
clang::ASTConsumer *CreateASTConsumer(clang::CompilerInstance &CI,
llvm::StringRef InFile) {
return new ConsumerType(CI.getDiagnostics(), CI.getSourceManager(), args_);
}
bool ParseArgs(const clang::CompilerInstance &CI,
const std::vector<std::string>& args) {
args_ = args;
return true;
}
void PrintHelp(llvm::raw_ostream& ros) {
}
private:
std::vector<std::string> args_;
};
}
static clang::FrontendPluginRegistry::Add<Action<ProblemsFinder> >
FindProblems("find-problems", "Find GC-unsafe places.");
static clang::FrontendPluginRegistry::Add<
Action<FunctionDeclarationFinder> >
DumpCallees("dump-callees", "Dump callees for each function.");
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