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