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// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#ifndef RUNTIME_VM_FRAME_LAYOUT_H_
#define RUNTIME_VM_FRAME_LAYOUT_H_
#include "platform/assert.h"
#include "platform/globals.h"
// FrameLayout structure captures configuration specific properties of the
// frame layout used by the runtime system and compiler.
//
// Runtime system uses runtime_frame_layout defined in stack_frame.h.
// Compiler uses compiler::target::frame_layout defined in runtime_api.h
namespace dart {
// Forward declarations.
class LocalVariable;
struct FrameLayout {
// The offset (in words) from FP to the first object.
intptr_t first_object_from_fp;
// The offset (in words) from FP to the last fixed object.
intptr_t last_fixed_object_from_fp;
// The offset (in words) from FP to the slot past the last parameter.
intptr_t param_end_from_fp;
// The offset (in words) from SP on entry (before frame is setup) to
// the last parameter.
intptr_t last_param_from_entry_sp;
// The offset (in words) from FP to the first local.
intptr_t first_local_from_fp;
// The fixed size of the frame.
intptr_t dart_fixed_frame_size;
// The offset (in words) from FP to the saved pool (if applicable).
intptr_t saved_caller_pp_from_fp;
// The offset (in words) from FP to the saved FP.
intptr_t saved_caller_fp_from_fp;
// The offset (in words) from FP to the saved return address.
intptr_t saved_caller_pc_from_fp;
// The offset (in words) from FP to the code object (if applicable).
intptr_t code_from_fp;
// Entry and exit frame layout.
intptr_t exit_link_slot_from_entry_fp;
// The number of fixed slots below the saved PC.
intptr_t saved_below_pc() const { return -first_local_from_fp; }
// Returns the FP-relative index where [variable] can be found (assumes
// [variable] is not captured), in words.
intptr_t FrameSlotForVariable(const LocalVariable* variable) const;
// Returns the FP-relative index where [variable_index] can be found (assumes
// [variable_index] comes from a [LocalVariable::index()], which is not
// captured).
intptr_t FrameSlotForVariableIndex(intptr_t index) const;
// Returns the variable index from a FP-relative index.
intptr_t VariableIndexForFrameSlot(intptr_t frame_slot) const {
if (frame_slot <= first_local_from_fp) {
return frame_slot - first_local_from_fp;
} else {
ASSERT(frame_slot > param_end_from_fp);
return frame_slot - param_end_from_fp;
}
}
// Called to initialize the stack frame layout during startup.
static void Init();
};
} // namespace dart
#endif // RUNTIME_VM_FRAME_LAYOUT_H_