v8/src/scopeinfo.h
2009-06-22 08:09:57 +00:00

237 lines
8.7 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_SCOPEINFO_H_
#define V8_SCOPEINFO_H_
#include "variables.h"
namespace v8 {
namespace internal {
// Scope information represents information about a functions's
// scopes (currently only one, because we don't do any inlining)
// and the allocation of the scope's variables. Scope information
// is stored in a compressed form with Code objects and is used
// at runtime (stack dumps, deoptimization, etc.).
//
// Historical note: In other VMs built by this team, ScopeInfo was
// usually called DebugInfo since the information was used (among
// other things) for on-demand debugging (Self, Smalltalk). However,
// DebugInfo seems misleading, since this information is primarily used
// in debugging-unrelated contexts.
// Forward defined as
// template <class Allocator = FreeStoreAllocationPolicy> class ScopeInfo;
template<class Allocator>
class ScopeInfo BASE_EMBEDDED {
public:
// Create a ScopeInfo instance from a scope.
explicit ScopeInfo(Scope* scope);
// Create a ScopeInfo instance from a Code object.
explicit ScopeInfo(Code* code);
// Write the ScopeInfo data into a Code object, and returns the
// amount of space that was needed. If no Code object is provided
// (NULL handle), Serialize() only returns the amount of space needed.
//
// This operations requires that the Code object has the correct amount
// of space for the ScopeInfo data; otherwise the operation fails (fatal
// error). Any existing scope info in the Code object is simply overwritten.
int Serialize(Code* code);
// Garbage collection support for scope info embedded in Code objects.
// This code is in ScopeInfo because only here we should have to know
// about the encoding.
static void IterateScopeInfo(Code* code, ObjectVisitor* v);
// --------------------------------------------------------------------------
// Lookup
Handle<String> function_name() const { return function_name_; }
Handle<String> parameter_name(int i) const { return parameters_[i]; }
int number_of_parameters() const { return parameters_.length(); }
Handle<String> stack_slot_name(int i) const { return stack_slots_[i]; }
int number_of_stack_slots() const { return stack_slots_.length(); }
Handle<String> context_slot_name(int i) const {
return context_slots_[i - Context::MIN_CONTEXT_SLOTS];
}
int number_of_context_slots() const {
int l = context_slots_.length();
return l == 0 ? 0 : l + Context::MIN_CONTEXT_SLOTS;
}
Handle<String> LocalName(int i) const;
int NumberOfLocals() const;
// --------------------------------------------------------------------------
// The following functions provide quick access to scope info details
// for runtime routines w/o the need to explicitly create a ScopeInfo
// object.
//
// ScopeInfo is the only class which should have to know about the
// encoding of it's information in a Code object, which is why these
// functions are in this class.
// Does this scope call eval.
static bool CallsEval(Code* code);
// Return the number of stack slots for code.
static int NumberOfStackSlots(Code* code);
// Return the number of context slots for code.
static int NumberOfContextSlots(Code* code);
// Lookup support for scope info embedded in Code objects. Returns
// the stack slot index for a given slot name if the slot is
// present; otherwise returns a value < 0. The name must be a symbol
// (canonicalized).
static int StackSlotIndex(Code* code, String* name);
// Lookup support for scope info embedded in Code objects. Returns the
// context slot index for a given slot name if the slot is present; otherwise
// returns a value < 0. The name must be a symbol (canonicalized).
// If the slot is present and mode != NULL, sets *mode to the corresponding
// mode for that variable.
static int ContextSlotIndex(Code* code, String* name, Variable::Mode* mode);
// Lookup support for scope info embedded in Code objects. Returns the
// parameter index for a given parameter name if the parameter is present;
// otherwise returns a value < 0. The name must be a symbol (canonicalized).
static int ParameterIndex(Code* code, String* name);
// Lookup support for scope info embedded in Code objects. Returns the
// function context slot index if the function name is present (named
// function expressions, only), otherwise returns a value < 0. The name
// must be a symbol (canonicalized).
static int FunctionContextSlotIndex(Code* code, String* name);
// --------------------------------------------------------------------------
// Debugging support
#ifdef DEBUG
void Print();
#endif
private:
Handle<String> function_name_;
bool calls_eval_;
List<Handle<String>, Allocator > parameters_;
List<Handle<String>, Allocator > stack_slots_;
List<Handle<String>, Allocator > context_slots_;
List<Variable::Mode, Allocator > context_modes_;
};
class ZoneScopeInfo: public ScopeInfo<ZoneListAllocationPolicy> {
public:
// Create a ZoneScopeInfo instance from a scope.
explicit ZoneScopeInfo(Scope* scope)
: ScopeInfo<ZoneListAllocationPolicy>(scope) {}
// Create a ZoneScopeInfo instance from a Code object.
explicit ZoneScopeInfo(Code* code)
: ScopeInfo<ZoneListAllocationPolicy>(code) {}
};
// Cache for mapping (code, property name) into context slot index.
// The cache contains both positive and negative results.
// Slot index equals -1 means the property is absent.
// Cleared at startup and prior to mark sweep collection.
class ContextSlotCache {
public:
// Lookup context slot index for (code, name).
// If absent, kNotFound is returned.
static int Lookup(Code* code,
String* name,
Variable::Mode* mode);
// Update an element in the cache.
static void Update(Code* code,
String* name,
Variable::Mode mode,
int slot_index);
// Clear the cache.
static void Clear();
static const int kNotFound = -2;
private:
inline static int Hash(Code* code, String* name);
#ifdef DEBUG
static void ValidateEntry(Code* code,
String* name,
Variable::Mode mode,
int slot_index);
#endif
static const int kLength = 256;
struct Key {
Code* code;
String* name;
};
struct Value {
Value(Variable::Mode mode, int index) {
ASSERT(ModeField::is_valid(mode));
ASSERT(IndexField::is_valid(index));
value_ = ModeField::encode(mode) | IndexField::encode(index);
ASSERT(mode == this->mode());
ASSERT(index == this->index());
}
inline Value(uint32_t value) : value_(value) {}
uint32_t raw() { return value_; }
Variable::Mode mode() { return ModeField::decode(value_); }
int index() { return IndexField::decode(value_); }
// Bit fields in value_ (type, shift, size). Must be public so the
// constants can be embedded in generated code.
class ModeField: public BitField<Variable::Mode, 0, 3> {};
class IndexField: public BitField<int, 3, 32-3> {};
private:
uint32_t value_;
};
static Key keys_[kLength];
static uint32_t values_[kLength];
};
} } // namespace v8::internal
#endif // V8_SCOPEINFO_H_