v8/src/scopes.h
fschneider@chromium.org 7d933936d3 Fix assigned variables analysis.
This change fixes a bug with the arguments object that occurred with
r4087 and r4088. The fix is not marking the arguments variable as trivial
since it can have side effects.


Review URL: http://codereview.chromium.org/851002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4099 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2010-03-11 10:28:40 +00:00

401 lines
15 KiB
C++

// Copyright 2006-2008 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.
#ifndef V8_SCOPES_H_
#define V8_SCOPES_H_
#include "ast.h"
#include "hashmap.h"
namespace v8 {
namespace internal {
// A hash map to support fast variable declaration and lookup.
class VariableMap: public HashMap {
public:
VariableMap();
// Dummy constructor. This constructor doesn't set up the map
// properly so don't use it unless you have a good reason.
explicit VariableMap(bool gotta_love_static_overloading);
virtual ~VariableMap();
Variable* Declare(Scope* scope,
Handle<String> name,
Variable::Mode mode,
bool is_valid_lhs,
Variable::Kind kind);
Variable* Lookup(Handle<String> name);
};
// The dynamic scope part holds hash maps for the variables that will
// be looked up dynamically from within eval and with scopes. The objects
// are allocated on-demand from Scope::NonLocal to avoid wasting memory
// and setup time for scopes that don't need them.
class DynamicScopePart : public ZoneObject {
public:
VariableMap* GetMap(Variable::Mode mode) {
int index = mode - Variable::DYNAMIC;
ASSERT(index >= 0 && index < 3);
return &maps_[index];
}
private:
VariableMap maps_[3];
};
// Global invariants after AST construction: Each reference (i.e. identifier)
// to a JavaScript variable (including global properties) is represented by a
// VariableProxy node. Immediately after AST construction and before variable
// allocation, most VariableProxy nodes are "unresolved", i.e. not bound to a
// corresponding variable (though some are bound during parse time). Variable
// allocation binds each unresolved VariableProxy to one Variable and assigns
// a location. Note that many VariableProxy nodes may refer to the same Java-
// Script variable.
class Scope: public ZoneObject {
public:
// ---------------------------------------------------------------------------
// Construction
enum Type {
EVAL_SCOPE, // the top-level scope for an 'eval' source
FUNCTION_SCOPE, // the top-level scope for a function
GLOBAL_SCOPE // the top-level scope for a program or a top-level eval
};
Scope(Scope* outer_scope, Type type);
virtual ~Scope() { }
// The scope name is only used for printing/debugging.
void SetScopeName(Handle<String> scope_name) { scope_name_ = scope_name; }
void Initialize(bool inside_with);
// ---------------------------------------------------------------------------
// Declarations
// Lookup a variable in this scope. Returns the variable or NULL if not found.
virtual Variable* LocalLookup(Handle<String> name);
// Lookup a variable in this scope or outer scopes.
// Returns the variable or NULL if not found.
virtual Variable* Lookup(Handle<String> name);
// Declare the function variable for a function literal. This variable
// is in an intermediate scope between this function scope and the the
// outer scope. Only possible for function scopes; at most one variable.
Variable* DeclareFunctionVar(Handle<String> name);
// Declare a local variable in this scope. If the variable has been
// declared before, the previously declared variable is returned.
virtual Variable* DeclareLocal(Handle<String> name, Variable::Mode mode);
// Declare an implicit global variable in this scope which must be a
// global scope. The variable was introduced (possibly from an inner
// scope) by a reference to an unresolved variable with no intervening
// with statements or eval calls.
Variable* DeclareGlobal(Handle<String> name);
// Add a parameter to the parameter list. The parameter must have been
// declared via Declare. The same parameter may occur more than once in
// the parameter list; they must be added in source order, from left to
// right.
void AddParameter(Variable* var);
// Create a new unresolved variable.
virtual VariableProxy* NewUnresolved(Handle<String> name, bool inside_with);
// Remove a unresolved variable. During parsing, an unresolved variable
// may have been added optimistically, but then only the variable name
// was used (typically for labels). If the variable was not declared, the
// addition introduced a new unresolved variable which may end up being
// allocated globally as a "ghost" variable. RemoveUnresolved removes
// such a variable again if it was added; otherwise this is a no-op.
void RemoveUnresolved(VariableProxy* var);
// Creates a new temporary variable in this scope and binds a proxy to it.
// The name is only used for printing and cannot be used to find the variable.
// In particular, the only way to get hold of the temporary is by keeping the
// VariableProxy* around.
virtual VariableProxy* NewTemporary(Handle<String> name);
// Adds the specific declaration node to the list of declarations in
// this scope. The declarations are processed as part of entering
// the scope; see codegen.cc:ProcessDeclarations.
void AddDeclaration(Declaration* declaration);
// ---------------------------------------------------------------------------
// Illegal redeclaration support.
// Set an expression node that will be executed when the scope is
// entered. We only keep track of one illegal redeclaration node per
// scope - the first one - so if you try to set it multiple times
// the additional requests will be silently ignored.
void SetIllegalRedeclaration(Expression* expression);
// Visit the illegal redeclaration expression. Do not call if the
// scope doesn't have an illegal redeclaration node.
void VisitIllegalRedeclaration(AstVisitor* visitor);
// Check if the scope has (at least) one illegal redeclaration.
bool HasIllegalRedeclaration() const { return illegal_redecl_ != NULL; }
// ---------------------------------------------------------------------------
// Scope-specific info.
// Inform the scope that the corresponding code contains a with statement.
void RecordWithStatement() { scope_contains_with_ = true; }
// Inform the scope that the corresponding code contains an eval call.
void RecordEvalCall() { scope_calls_eval_ = true; }
// ---------------------------------------------------------------------------
// Predicates.
// Specific scope types.
bool is_eval_scope() const { return type_ == EVAL_SCOPE; }
bool is_function_scope() const { return type_ == FUNCTION_SCOPE; }
bool is_global_scope() const { return type_ == GLOBAL_SCOPE; }
// Information about which scopes calls eval.
bool calls_eval() const { return scope_calls_eval_; }
bool outer_scope_calls_eval() const { return outer_scope_calls_eval_; }
// Is this scope inside a with statement.
bool inside_with() const { return scope_inside_with_; }
// Does this scope contain a with statement.
bool contains_with() const { return scope_contains_with_; }
// The scope immediately surrounding this scope, or NULL.
Scope* outer_scope() const { return outer_scope_; }
// ---------------------------------------------------------------------------
// Accessors.
// A new variable proxy corresponding to the (function) receiver.
VariableProxy* receiver() const {
VariableProxy* proxy =
new VariableProxy(Factory::this_symbol(), true, false);
proxy->BindTo(receiver_);
return proxy;
}
// The variable holding the function literal for named function
// literals, or NULL.
// Only valid for function scopes.
Variable* function() const {
ASSERT(is_function_scope());
return function_;
}
// Parameters. The left-most parameter has index 0.
// Only valid for function scopes.
Variable* parameter(int index) const {
ASSERT(is_function_scope());
return params_[index];
}
int num_parameters() const { return params_.length(); }
// The local variable 'arguments' if we need to allocate it; NULL otherwise.
// If arguments() exist, arguments_shadow() exists, too.
VariableProxy* arguments() const { return arguments_; }
// The '.arguments' shadow variable if we need to allocate it; NULL otherwise.
// If arguments_shadow() exist, arguments() exists, too.
VariableProxy* arguments_shadow() const { return arguments_shadow_; }
// Declarations list.
ZoneList<Declaration*>* declarations() { return &decls_; }
// ---------------------------------------------------------------------------
// Variable allocation.
// Collect all used locals in this scope.
template<class Allocator>
void CollectUsedVariables(List<Variable*, Allocator>* locals);
// Resolve and fill in the allocation information for all variables
// in this scopes. Must be called *after* all scopes have been
// processed (parsed) to ensure that unresolved variables can be
// resolved properly.
//
// In the case of code compiled and run using 'eval', the context
// parameter is the context in which eval was called. In all other
// cases the context parameter is an empty handle.
void AllocateVariables(Handle<Context> context);
// Result of variable allocation.
int num_stack_slots() const { return num_stack_slots_; }
int num_heap_slots() const { return num_heap_slots_; }
// Make sure this scope and all outer scopes are eagerly compiled.
void ForceEagerCompilation() { force_eager_compilation_ = true; }
// Determine if we can use lazy compilation for this scope.
bool AllowsLazyCompilation() const;
// True if the outer context of this scope is always the global context.
bool HasTrivialOuterContext() const;
// The number of contexts between this and scope; zero if this == scope.
int ContextChainLength(Scope* scope);
// ---------------------------------------------------------------------------
// Debugging.
#ifdef DEBUG
void Print(int n = 0); // n = indentation; n < 0 => don't print recursively
#endif
// ---------------------------------------------------------------------------
// Implementation.
protected:
friend class ParserFactory;
explicit Scope(Type type);
// Scope tree.
Scope* outer_scope_; // the immediately enclosing outer scope, or NULL
ZoneList<Scope*> inner_scopes_; // the immediately enclosed inner scopes
// The scope type.
Type type_;
// Debugging support.
Handle<String> scope_name_;
// The variables declared in this scope:
//
// All user-declared variables (incl. parameters). For global scopes
// variables may be implicitly 'declared' by being used (possibly in
// an inner scope) with no intervening with statements or eval calls.
VariableMap variables_;
// Compiler-allocated (user-invisible) temporaries.
ZoneList<Variable*> temps_;
// Parameter list in source order.
ZoneList<Variable*> params_;
// Variables that must be looked up dynamically.
DynamicScopePart* dynamics_;
// Unresolved variables referred to from this scope.
ZoneList<VariableProxy*> unresolved_;
// Declarations.
ZoneList<Declaration*> decls_;
// Convenience variable.
Variable* receiver_;
// Function variable, if any; function scopes only.
Variable* function_;
// Convenience variable; function scopes only.
VariableProxy* arguments_;
// Convenience variable; function scopes only.
VariableProxy* arguments_shadow_;
// Illegal redeclaration.
Expression* illegal_redecl_;
// Scope-specific information.
bool scope_inside_with_; // this scope is inside a 'with' of some outer scope
bool scope_contains_with_; // this scope contains a 'with' statement
bool scope_calls_eval_; // this scope contains an 'eval' call
// Computed via PropagateScopeInfo.
bool outer_scope_calls_eval_;
bool inner_scope_calls_eval_;
bool outer_scope_is_eval_scope_;
bool force_eager_compilation_;
// Computed via AllocateVariables; function scopes only.
int num_stack_slots_;
int num_heap_slots_;
// Create a non-local variable with a given name.
// These variables are looked up dynamically at runtime.
Variable* NonLocal(Handle<String> name, Variable::Mode mode);
// Variable resolution.
Variable* LookupRecursive(Handle<String> name,
bool inner_lookup,
Variable** invalidated_local);
void ResolveVariable(Scope* global_scope,
Handle<Context> context,
VariableProxy* proxy);
void ResolveVariablesRecursively(Scope* global_scope,
Handle<Context> context);
// Scope analysis.
bool PropagateScopeInfo(bool outer_scope_calls_eval,
bool outer_scope_is_eval_scope);
bool HasTrivialContext() const;
// Predicates.
bool MustAllocate(Variable* var);
bool MustAllocateInContext(Variable* var);
bool HasArgumentsParameter();
// Variable allocation.
void AllocateStackSlot(Variable* var);
void AllocateHeapSlot(Variable* var);
void AllocateParameterLocals();
void AllocateNonParameterLocal(Variable* var);
void AllocateNonParameterLocals();
void AllocateVariablesRecursively();
};
class DummyScope : public Scope {
public:
DummyScope() : Scope(GLOBAL_SCOPE) {
outer_scope_ = this;
}
virtual Variable* Lookup(Handle<String> name) { return NULL; }
virtual Variable* Declare(Handle<String> name, Variable::Mode mode) {
return NULL;
}
virtual VariableProxy* NewUnresolved(Handle<String> name, bool inside_with) {
return NULL;
}
virtual VariableProxy* NewTemporary(Handle<String> name) { return NULL; }
};
} } // namespace v8::internal
#endif // V8_SCOPES_H_