1 /*
2 * Copyright (c) 1997, 2018, 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_VM_CODE_LOCATION_HPP
26 #define SHARE_VM_CODE_LOCATION_HPP
27
28 #include "asm/assembler.hpp"
29 #include "code/vmreg.hpp"
30 #include "memory/allocation.hpp"
31
32 // A Location describes a concrete machine variable location
33 // (such as integer or floating point register or a stack-held
34 // variable). Used when generating debug-information for nmethods.
35 //
36 // Encoding:
37 //
38 // bits (use low bits for best compression):
39 // Type: [3..0]
40 // Where: [4]
41 // Offset: [31..5]
42
43 class Location {
44 friend class VMStructs;
45 public:
46 enum Where {
47 on_stack,
48 in_register
49 };
50
51 enum Type {
52 invalid, // Invalid location
53 normal, // Ints, floats, double halves
54 oop, // Oop (please GC me!)
55 int_in_long, // Integer held in long register
56 lng, // Long held in one register
57 float_in_dbl, // Float held in double register
58 dbl, // Double held in one register
59 addr, // JSR return address
60 narrowoop // Narrow Oop (please GC me!)
61 };
62
63
64 private:
65 enum {
66 TYPE_MASK = (juint) 0x0F,
67 TYPE_SHIFT = 0,
68 WHERE_MASK = (juint) 0x10,
69 WHERE_SHIFT = 4,
70 OFFSET_MASK = (juint) 0xFFFFFFE0,
71 OFFSET_SHIFT = 5
72 };
73
74 juint _value;
75
76 // Create a bit-packed Location
77 Location(Where where_, Type type_, unsigned offset_) {
78 set(where_, type_, offset_);
79 assert( where () == where_ , "" );
80 assert( type () == type_ , "" );
81 assert( offset() == offset_, "" );
82 }
83
84 inline void set(Where where_, Type type_, unsigned offset_) {
85 _value = (juint) ((where_ << WHERE_SHIFT) |
86 (type_ << TYPE_SHIFT) |
87 ((offset_ << OFFSET_SHIFT) & OFFSET_MASK));
88 }
89
90 public:
91
92 // Stack location Factory. Offset is 4-byte aligned; remove low bits
93 static Location new_stk_loc( Type t, int offset ) { return Location(on_stack,t,offset>>LogBytesPerInt); }
94 // Register location Factory
95 static Location new_reg_loc( Type t, VMReg reg ) { return Location(in_register, t, reg->value()); }
96 // Default constructor
97 Location() { set(on_stack,invalid,0); }
98
99 // Bit field accessors
100 Where where() const { return (Where) ((_value & WHERE_MASK) >> WHERE_SHIFT);}
101 Type type() const { return (Type) ((_value & TYPE_MASK) >> TYPE_SHIFT); }
102 unsigned offset() const { return (unsigned) ((_value & OFFSET_MASK) >> OFFSET_SHIFT); }
103
104 // Accessors
105 bool is_register() const { return where() == in_register; }
106 bool is_stack() const { return where() == on_stack; }
107
108 int stack_offset() const { assert(where() == on_stack, "wrong Where"); return offset()<<LogBytesPerInt; }
109 int register_number() const { assert(where() == in_register, "wrong Where"); return offset() ; }
110
111 VMReg reg() const { assert(where() == in_register, "wrong Where"); return VMRegImpl::as_VMReg(offset()) ; }
112
113 // Printing
114 void print_on(outputStream* st) const;
115
116 // Serialization of debugging information
117 Location(DebugInfoReadStream* stream);
118 void write_on(DebugInfoWriteStream* stream);
119
120 // check
121 static bool legal_offset_in_bytes(int offset_in_bytes);
122 };
123
124 #endif // SHARE_VM_CODE_LOCATION_HPP