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