comparison gcc/config/m32c/m32c.abi @ 0:a06113de4d67

first commit
author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
parents
children 04ced10e8804
comparison
equal deleted inserted replaced
-1:000000000000 0:a06113de4d67
1 Target Definitions for R8C/M16C/M32C
2 Copyright (C) 2005, 2007
3 Free Software Foundation, Inc.
4 Contributed by Red Hat.
5
6 This file is part of GCC.
7
8 GCC is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published
10 by the Free Software Foundation; either version 3, or (at your
11 option) any later version.
12
13 GCC is distributed in the hope that it will be useful, but WITHOUT
14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
16 License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>.
21
22
23 These are just some random notes I used during development of this
24 port. Please don't consider these to be "official" specifications,
25 just additional information to help make the code easier to
26 understand.
27
28
29 Frame
30 =====
31
32 +--------------------
33 | incoming args
34 +--------------------
35 | return Address
36 osp -> +--------------------
37 | saved fp
38 fp -> +--------------------
39 | local data
40 +--------------------
41 | saved regs
42 +--------------------
43 | outgoing args (opt)
44 sp -> +--------------------
45
46 Argument Passing
47 ================
48
49 r8c, m16c
50 ---------
51
52 First arg may be passed in r1l or r1 if it (1) fits (QImode or
53 HImode), (2) is named, and (3) is an integer or pointer type (no
54 structs, floats, etc). Otherwise, it's passed on the stack.
55
56 Second arg may be passed in r2, same restrictions (but not QImode),
57 even if the first arg is passed on the stack.
58
59 Third and further args are passed on the stack. No padding is used,
60 stack "alignment" is 8 bits.
61
62 m32cm, m32c
63 -----------
64 First arg may be passed in r0l or r0, same restrictions as above.
65
66 Second and further args are passed on the stack. Padding is used
67 after QImode parameters (i.e. lower-addressed byte is the value,
68 higher-addressed byte is the padding), stack "alignment" is 16 bits.
69
70
71 Return Value
72 ============
73
74 r8c, m16c
75 ---------
76
77 QImode in r0l
78 HImode in r0
79 near pointer in r0
80 (desired)
81 SImode in r2r0
82 far pointer in r2r0
83 (actual)
84 Anything bigger than 16 bits is returned in memory, at mem0 (mem0
85 through mem15 are provided by libgcc.a)
86
87 Aggregate values (regardless of size) are returned by pushing a
88 pointer to a temporary area on the stack after the args are pushed.
89 The function fills in this area with the value. Note that this
90 pointer on the stack does not affect how register arguments, if any,
91 are configured.
92
93 m32cm, m32c
94 -----------
95 Same.
96
97
98 Registers Preserved Across Calls
99 ================================
100
101 r8c, m16c
102 ---------
103 sb, fb, sp (i.e. nearly all registers are call clobbered)
104
105 m32cm, m32c
106 -----------
107 r1, r2, r3, a0, a1, sb, fb, sp
108 (except when used for return values)
109
110
111 Interrupt Handlers
112 ==================
113
114 The stack frame is slightly different for interrupt handlers, because
115 (1) we don't have a usable parent frame, and (2) we have to use
116 special instructions to return and thus must save/restore everything
117 differently.
118
119 +--------------------
120 | program state
121 osp -> +--------------------
122 | return address
123 +--------------------
124 | saved r0..fp (pushm)
125 fp -> +--------------------
126 | local data
127 +--------------------
128 | saved regs mem0..mem15
129 +--------------------
130 | outgoing args (opt)
131 sp -> +--------------------
132