sysdeps/alpha/div_libc.h

   1 /* Copyright (C) 2004-2023 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
  58 1:      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
 100 DIVBYZERO:
 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