1/* Copyright (C) 2004-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library. If not, see
16 <https://www.gnu.org/licenses/>. */
17
18/* Common bits for implementing software divide. */
19
20#include <sysdep.h>
21#ifdef __linux__
22# include <asm/gentrap.h>
23# include <asm/pal.h>
24#else
25# include <machine/pal.h>
26#endif
27
28/* These are not normal C functions. Argument registers are t10 and t11;
29 the result goes in t12; the return address is in t9. Only t12 and AT
30 may be clobbered. */
31#define X t10
32#define Y t11
33#define RV t12
34#define RA t9
35
36/* The secureplt format does not allow the division routines to be called
37 via plt; there aren't enough registers free to be clobbered. Avoid
38 setting the symbol type to STT_FUNC, so that the linker won't be tempted
39 to create a plt entry. */
40#define funcnoplt notype
41
42/* None of these functions should use implicit anything. */
43 .set nomacro
44 .set noat
45
46/* Code fragment to invoke _mcount for profiling. This should be invoked
47 directly after allocation of the stack frame. */
48.macro CALL_MCOUNT
49#ifdef PROF
50 stq ra, 0(sp)
51 stq pv, 8(sp)
52 stq gp, 16(sp)
53 cfi_rel_offset (ra, 0)
54 cfi_rel_offset (pv, 8)
55 cfi_rel_offset (gp, 16)
56 br AT, 1f
57 .set macro
581: ldgp gp, 0(AT)
59 mov RA, ra
60 lda AT, _mcount
61 jsr AT, (AT), _mcount
62 .set nomacro
63 ldq ra, 0(sp)
64 ldq pv, 8(sp)
65 ldq gp, 16(sp)
66 cfi_restore (ra)
67 cfi_restore (pv)
68 cfi_restore (gp)
69 /* Realign subsequent code with what we'd have without this
70 macro at all. This means aligned with one arithmetic insn
71 used within the bundle. */
72 .align 4
73 nop
74#endif
75.endm
76
77/* In order to make the below work, all top-level divide routines must
78 use the same frame size. */
79#define FRAME 64
80
81/* Code fragment to generate an integer divide-by-zero fault. When
82 building libc.so, we arrange for there to be one copy of this code
83 placed late in the dso, such that all branches are forward. When
84 building libc.a, we use multiple copies to avoid having an out of
85 range branch. Users should jump to DIVBYZERO. */
86
87.macro DO_DIVBYZERO
88#ifdef PIC
89#define DIVBYZERO __divbyzero
90 .section .gnu.linkonce.t.divbyzero, "ax", @progbits
91 .globl __divbyzero
92 .type __divbyzero, @function
93 .usepv __divbyzero, no
94 .hidden __divbyzero
95#else
96#define DIVBYZERO $divbyzero
97#endif
98
99 .align 4
100DIVBYZERO:
101 cfi_startproc
102 cfi_return_column (RA)
103 cfi_def_cfa_offset (FRAME)
104
105 mov a0, RV
106 unop
107 lda a0, GEN_INTDIV
108 call_pal PAL_gentrap
109
110 mov RV, a0
111 clr RV
112 lda sp, FRAME(sp)
113 cfi_def_cfa_offset (0)
114 ret $31, (RA), 1
115
116 cfi_endproc
117 .size DIVBYZERO, .-DIVBYZERO
118.endm
119
120/* Like the ev6 instructions, but fall back to stack use on prior machines. */
121
122 .arch ev6
123
124.macro _ITOFS gr, fr, slot
125#ifdef __alpha_fix__
126 itofs \gr, \fr
127#else
128 stl \gr, \slot(sp)
129 lds \fr, \slot(sp)
130#endif
131.endm
132
133.macro _ITOFT gr, fr, slot
134#ifdef __alpha_fix__
135 itoft \gr, \fr
136#else
137 stq \gr, \slot(sp)
138 ldt \fr, \slot(sp)
139#endif
140.endm
141
142.macro _FTOIT fr, gr, slot
143#ifdef __alpha_fix__
144 ftoit \fr, \gr
145#else
146 stt \fr, \slot(sp)
147 ldq \gr, \slot(sp)
148#endif
149.endm
150
151/* Similarly, but move two registers. Schedules better for pre-ev6. */
152
153.macro _ITOFT2 gr1, fr1, slot1, gr2, fr2, slot2
154#ifdef __alpha_fix__
155 itoft \gr1, \fr1
156 itoft \gr2, \fr2
157#else
158 stq \gr1, \slot1(sp)
159 stq \gr2, \slot2(sp)
160 ldt \fr1, \slot1(sp)
161 ldt \fr2, \slot2(sp)
162#endif
163.endm
164

source code of glibc/sysdeps/alpha/div_libc.h