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The location.hpp Java example source code
/*
* Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_VM_CODE_LOCATION_HPP
#define SHARE_VM_CODE_LOCATION_HPP
#include "asm/assembler.hpp"
#include "code/vmreg.hpp"
#include "memory/allocation.hpp"
// A Location describes a concrete machine variable location
// (such as integer or floating point register or a stack-held
// variable). Used when generating debug-information for nmethods.
//
// Encoding:
//
// bits (use low bits for best compression):
// Type: [3..0]
// Where: [4]
// Offset: [31..5]
class Location VALUE_OBJ_CLASS_SPEC {
friend class VMStructs;
public:
enum Where {
on_stack,
in_register
};
enum Type {
invalid, // Invalid location
normal, // Ints, floats, double halves
oop, // Oop (please GC me!)
int_in_long, // Integer held in long register
lng, // Long held in one register
float_in_dbl, // Float held in double register
dbl, // Double held in one register
addr, // JSR return address
narrowoop // Narrow Oop (please GC me!)
};
private:
enum {
TYPE_MASK = (juint) 0x0F,
TYPE_SHIFT = 0,
WHERE_MASK = (juint) 0x10,
WHERE_SHIFT = 4,
OFFSET_MASK = (juint) 0xFFFFFFE0,
OFFSET_SHIFT = 5
};
juint _value;
// Create a bit-packed Location
Location(Where where_, Type type_, unsigned offset_) {
set(where_, type_, offset_);
assert( where () == where_ , "" );
assert( type () == type_ , "" );
assert( offset() == offset_, "" );
}
inline void set(Where where_, Type type_, unsigned offset_) {
_value = (juint) ((where_ << WHERE_SHIFT) |
(type_ << TYPE_SHIFT) |
((offset_ << OFFSET_SHIFT) & OFFSET_MASK));
}
public:
// Stack location Factory. Offset is 4-byte aligned; remove low bits
static Location new_stk_loc( Type t, int offset ) { return Location(on_stack,t,offset>>LogBytesPerInt); }
// Register location Factory
static Location new_reg_loc( Type t, VMReg reg ) { return Location(in_register, t, reg->value()); }
// Default constructor
Location() { set(on_stack,invalid,0); }
// Bit field accessors
Where where() const { return (Where) ((_value & WHERE_MASK) >> WHERE_SHIFT);}
Type type() const { return (Type) ((_value & TYPE_MASK) >> TYPE_SHIFT); }
unsigned offset() const { return (unsigned) ((_value & OFFSET_MASK) >> OFFSET_SHIFT); }
// Accessors
bool is_register() const { return where() == in_register; }
bool is_stack() const { return where() == on_stack; }
int stack_offset() const { assert(where() == on_stack, "wrong Where"); return offset()<
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