1 /*
2 * Copyright (c) 1997, 2019, 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 #ifndef SHARE_CODE_LOCATION_HPP
26 #define SHARE_CODE_LOCATION_HPP
27
28 #include "asm/assembler.hpp"
29 #include "code/vmreg.hpp"
30
31 class DebugInfoReadStream;
32 class DebugInfoWriteStream;
33
34 // A Location describes a concrete machine variable location
35 // (such as integer or floating point register or a stack-held
36 // variable). Used when generating debug-information for nmethods.
37 //
38 // Encoding:
39 //
40 // bits (use low bits for best compression):
41 // Type: [3..0]
42 // Where: [4]
43 // Offset: [31..5]
44
45 class Location {
46 friend class VMStructs;
47 public:
48 enum Where {
49 on_stack,
50 in_register
51 };
52
53 enum Type {
54 invalid, // Invalid location
55 normal, // Ints, floats, double halves
56 oop, // Oop (please GC me!)
57 int_in_long, // Integer held in long register
58 lng, // Long held in one register
59 float_in_dbl, // Float held in double register
60 dbl, // Double held in one register
61 addr, // JSR return address
62 narrowoop // Narrow Oop (please GC me!)
63 };
64
65
66 private:
67 enum {
68 TYPE_MASK = (juint) 0x0F,
69 TYPE_SHIFT = 0,
70 WHERE_MASK = (juint) 0x10,
71 WHERE_SHIFT = 4,
72 OFFSET_MASK = (juint) 0xFFFFFFE0,
73 OFFSET_SHIFT = 5
74 };
75
76 juint _value;
77
78 // Create a bit-packed Location
79 Location(Where where_, Type type_, unsigned offset_) {
80 set(where_, type_, offset_);
81 assert( where () == where_ , "" );
82 assert( type () == type_ , "" );
83 assert( offset() == offset_, "" );
84 }
85
86 inline void set(Where where_, Type type_, unsigned offset_) {
87 _value = (juint) ((where_ << WHERE_SHIFT) |
88 (type_ << TYPE_SHIFT) |
89 ((offset_ << OFFSET_SHIFT) & OFFSET_MASK));
90 }
91
92 public:
93
94 // Stack location Factory. Offset is 4-byte aligned; remove low bits
95 static Location new_stk_loc( Type t, int offset ) { return Location(on_stack,t,offset>>LogBytesPerInt); }
96 // Register location Factory
97 static Location new_reg_loc( Type t, VMReg reg ) { return Location(in_register, t, reg->value()); }
98 // Default constructor
99 Location() { set(on_stack,invalid,0); }
100
101 // Bit field accessors
102 Where where() const { return (Where) ((_value & WHERE_MASK) >> WHERE_SHIFT);}
103 Type type() const { return (Type) ((_value & TYPE_MASK) >> TYPE_SHIFT); }
104 unsigned offset() const { return (unsigned) ((_value & OFFSET_MASK) >> OFFSET_SHIFT); }
105
106 // Accessors
107 bool is_register() const { return where() == in_register; }
108 bool is_stack() const { return where() == on_stack; }
109
110 int stack_offset() const { assert(where() == on_stack, "wrong Where"); return offset()<<LogBytesPerInt; }
111 int register_number() const { assert(where() == in_register, "wrong Where"); return offset() ; }
112
113 VMReg reg() const { assert(where() == in_register, "wrong Where"); return VMRegImpl::as_VMReg(offset()) ; }
114
115 // Printing
116 void print_on(outputStream* st) const;
117
118 // Serialization of debugging information
119 Location(DebugInfoReadStream* stream);
120 void write_on(DebugInfoWriteStream* stream);
121
122 // check
123 static bool legal_offset_in_bytes(int offset_in_bytes);
124 };
125
126 #endif // SHARE_CODE_LOCATION_HPP