location.hpp revision 1472:c18cbe5936b8
1/* 2 * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25// A Location describes a concrete machine variable location 26// (such as integer or floating point register or a stack-held 27// variable). Used when generating debug-information for nmethods. 28// 29// Encoding: 30// 31// bits (use low bits for best compression): 32// Type: [3..0] 33// Where: [4] 34// Offset: [31..5] 35 36class Location VALUE_OBJ_CLASS_SPEC { 37 friend class VMStructs; 38 public: 39 enum Where { 40 on_stack, 41 in_register 42 }; 43 44 enum Type { 45 invalid, // Invalid location 46 normal, // Ints, floats, double halves 47 oop, // Oop (please GC me!) 48 int_in_long, // Integer held in long register 49 lng, // Long held in one register 50 float_in_dbl, // Float held in double register 51 dbl, // Double held in one register 52 addr, // JSR return address 53 narrowoop // Narrow Oop (please GC me!) 54 }; 55 56 57 private: 58 enum { 59 TYPE_MASK = (juint) 0x0F, 60 TYPE_SHIFT = 0, 61 WHERE_MASK = (juint) 0x10, 62 WHERE_SHIFT = 4, 63 OFFSET_MASK = (juint) 0xFFFFFFE0, 64 OFFSET_SHIFT = 5 65 }; 66 67 juint _value; 68 69 // Create a bit-packed Location 70 Location(Where where_, Type type_, unsigned offset_) { 71 set(where_, type_, offset_); 72 assert( where () == where_ , "" ); 73 assert( type () == type_ , "" ); 74 assert( offset() == offset_, "" ); 75 } 76 77 inline void set(Where where_, Type type_, unsigned offset_) { 78 _value = (juint) ((where_ << WHERE_SHIFT) | 79 (type_ << TYPE_SHIFT) | 80 ((offset_ << OFFSET_SHIFT) & OFFSET_MASK)); 81 } 82 83 public: 84 85 // Stack location Factory. Offset is 4-byte aligned; remove low bits 86 static Location new_stk_loc( Type t, int offset ) { return Location(on_stack,t,offset>>LogBytesPerInt); } 87 // Register location Factory 88 static Location new_reg_loc( Type t, VMReg reg ) { return Location(in_register, t, reg->value()); } 89 // Default constructor 90 Location() { set(on_stack,invalid,0); } 91 92 // Bit field accessors 93 Where where() const { return (Where) ((_value & WHERE_MASK) >> WHERE_SHIFT);} 94 Type type() const { return (Type) ((_value & TYPE_MASK) >> TYPE_SHIFT); } 95 unsigned offset() const { return (unsigned) ((_value & OFFSET_MASK) >> OFFSET_SHIFT); } 96 97 // Accessors 98 bool is_register() const { return where() == in_register; } 99 bool is_stack() const { return where() == on_stack; } 100 101 int stack_offset() const { assert(where() == on_stack, "wrong Where"); return offset()<<LogBytesPerInt; } 102 int register_number() const { assert(where() == in_register, "wrong Where"); return offset() ; } 103 104 VMReg reg() const { assert(where() == in_register, "wrong Where"); return VMRegImpl::as_VMReg(offset()) ; } 105 106 // Printing 107 void print_on(outputStream* st) const; 108 109 // Serialization of debugging information 110 Location(DebugInfoReadStream* stream); 111 void write_on(DebugInfoWriteStream* stream); 112 113 // check 114 static bool legal_offset_in_bytes(int offset_in_bytes); 115}; 116