/* Copyright (C) 2008-2023 Free Software Foundation, Inc.
Contributor: Joern Rennecke <joern.rennecke@embecosm.com>
on behalf of Synopsys Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "arc-ieee-754.h"
#if 0 /* DEBUG */
.global __addsf3
FUNC(__addsf3)
.balign 4
__addsf3:
push_s blink
push_s r1
bl.d __addsf3_c
push_s r0
ld_s r1,[sp,4]
st_s r0,[sp,4]
bl.d __addsf3_asm
pop_s r0
pop_s r1
pop_s blink
cmp r0,r1
jeq_s [blink]
bl abort
ENDFUNC(__addsf3)
.global __subsf3
FUNC(__subsf3)
.balign 4
__subsf3:
push_s blink
push_s r1
bl.d __subsf3_c
push_s r0
ld_s r1,[sp,4]
st_s r0,[sp,4]
bl.d __subsf3_asm
pop_s r0
pop_s r1
pop_s blink
cmp r0,r1
jeq_s [blink]
bl abort
ENDFUNC(__subsf3)
#define __addsf3 __addsf3_asm
#define __subsf3 __subsf3_asm
#endif /* DEBUG */
/* N.B. This is optimized for ARC700.
ARC600 has very different scheduling / instruction selection criteria. */
/* inputs: r0, r1
output: r0
clobber: r1-r10, r12, flags */
.balign 4
.global __addsf3
.global __subsf3
FUNC(__addsf3)
FUNC(__subsf3)
.long 0x7f800000 ; exponent mask
__subsf3:
bxor_l r1,r1,31
__addsf3:
ld r9,[pcl,-8]
bmsk r4,r0,30
xor r10,r0,r1
and r6,r1,r9
sub.f r12,r4,r6
asr_s r12,r12,23
blo .Ldbl1_gt
brhs r4,r9,.Linf_nan
brne r12,0,.Lsmall_shift
brge r10,0,.Ladd_same_exp ; r12 == 0
/* After subtracting, we need to normalize; when shifting to place the
leading 1 into position for the implicit 1 and adding that to DBL0,
we increment the exponent. Thus, we have to subtract one more than
the shift count from the exponent beforehand. Iff the exponent drops thus
below zero (before adding in the fraction with the leading one), we have
generated a denormal number. Denormal handling is basicallly reducing the
shift count so that we produce a zero exponent instead; FWIW, this way
the shift count can become zero (if we started out with exponent 1).
On the plus side, we don't need to check for denorm input, the result
of subtracing these looks just the same as denormals generated during
subtraction. */
bmsk r7,r1,30
breq r4,r7,.Lret0
sub.f r5,r4,r7
lsr r12,r4,23
neg.cs r5,r5
norm r3,r5
bmsk r2,r0,22
sub_s r3,r3,6
min r12,r12,r3
bic r1,r0,r2
sub_s r3,r12,1
asl_s r12,r12,23
asl r2,r5,r3
sub_s r1,r1,r12
add_s r0,r1,r2
j_s.d [blink]
bxor.cs r0,r0,31
.balign 4
.Linf_nan:
; If both inputs are inf, but with different signs, the result is NaN.
asr r12,r10,31
or_s r1,r1,r12
j_s.d [blink]
or.eq r0,r0,r1
.balign 4
.Ladd_same_exp:
/* This is a special case because we can't test for need to shift
down by checking if bit 23 of DBL0 changes. OTOH, here we know
that we always need to shift down. */
; adding the two floating point numbers together makes the sign
; cancel out and apear as carry; the exponent is doubled, and the
; fraction also in need of shifting left by one. The two implicit
; ones of the sources make an implicit 1 of the result, again
; non-existent in a place shifted by one.
add.f r0,r0,r1
btst_s r0,1
breq r6,0,.Ldenorm_add
add.ne r0,r0,1 ; round to even.
rrc r0,r0
bmsk r1,r9,23
add r0,r0,r1 ; increment exponent
bic.f 0,r9,r0; check for overflow -> infinity.
jne_l [blink]
mov_s r0,r9
j_s.d [blink]
bset.cs r0,r0,31
.Ldenorm_add:
j_s.d [blink]
add r0,r4,r1
.Lret_dbl0:
j_s [blink]
.balign 4
.Lsmall_shift:
brhi r12,25,.Lret_dbl0
breq.d r6,0,.Ldenorm_small_shift
bmsk_s r1,r1,22
bset_s r1,r1,23
.Lfixed_denorm_small_shift:
neg r8,r12
asl r5,r1,r8
brge.d r10,0,.Ladd
lsr_l r1,r1,r12
/* subtract, abs(DBL0) > abs(DBL1) */
/* DBL0: original values
DBL1: fraction with explicit leading 1, shifted into place
r4: orig. DBL0 & 0x7fffffff
r6: orig. DBL1 & 0x7f800000
r9: 0x7f800000
r10: orig. DBL0H ^ DBL1H
r5 : guard bits */
.balign 4
.Lsub:
neg.f r12,r5
bmsk r3,r0,22
bset r5,r3,23
sbc.f r4,r5,r1
beq.d .Large_cancel_sub
bic r7,r0,r3
norm r3,r4
bmsk r6,r7,30
.Lsub_done:
sub_s r3,r3,6
breq r3,1,.Lsub_done_noshift
asl r5,r3,23
sub_l r3,r3,1
brlo r6,r5,.Ldenorm_sub
sub r0,r7,r5
neg_s r1,r3
lsr.f r2,r12,r1
asl_s r12,r12,r3
btst_s r2,0
bmsk.eq.f r12,r12,30
asl r5,r4,r3
add_s r0,r0,r2
adc.ne r0,r0,0
j_s.d [blink]
add_l r0,r0,r5
.Lret0:
j_s.d [blink]
mov_l r0,0
.balign 4
.Ldenorm_small_shift:
brne.d r12,1,.Lfixed_denorm_small_shift
sub_s r12,r12,1
brlt.d r10,0,.Lsub
mov_s r5,r12 ; zero r5, and align following code
.Ladd: ; Both bit 23 of DBL1 and bit 0 of r5 are clear.
bmsk r2,r0,22
add_s r2,r2,r1
bbit0.d r2,23,.Lno_shiftdown
add_s r0,r0,r1
bic.f 0,r9,r0; check for overflow -> infinity; eq : infinity
bmsk r1,r2,22
lsr.ne.f r2,r2,2; cc: even ; hi: might round down
lsr.ne r1,r1,1
rcmp.hi r5,1; hi : round down
bclr.hi r0,r0,0
j_l.d [blink]
sub_s r0,r0,r1
/* r4: DBL0H & 0x7fffffff
r6: DBL1H & 0x7f800000
r9: 0x7f800000
r10: sign difference
r12: shift count (negative) */
.balign 4
.Ldbl1_gt:
brhs r6,r9,.Lret_dbl1 ; inf or NaN
neg r8,r12
brhi r8,25,.Lret_dbl1
.Lsmall_shift_dbl0:
breq.d r6,0,.Ldenorm_small_shift_dbl0
bmsk_s r0,r0,22
bset_s r0,r0,23
.Lfixed_denorm_small_shift_dbl0:
asl r5,r0,r12
brge.d r10,0,.Ladd_dbl1_gt
lsr r0,r0,r8
/* subtract, abs(DBL0) < abs(DBL1) */
/* DBL0: fraction with explicit leading 1, shifted into place
DBL1: original value
r6: orig. DBL1 & 0x7f800000
r9: 0x7f800000
r5: guard bits */
.balign 4
.Lrsub:
neg.f r12,r5
bmsk r5,r1,22
bic r7,r1,r5
bset r5,r5,23
sbc.f r4,r5,r0
bne.d .Lsub_done ; note: r6 is already set up.
norm r3,r4
/* Fall through */
/* r4:r12 : unnormalized result fraction
r7: result sign and exponent */
/* When seeing large cancellation, only the topmost guard bit might be set. */
.balign 4
.Large_cancel_sub:
breq_s r12,0,.Lret0
sub r0,r7,24<<23
xor.f 0,r0,r7 ; test if exponent is negative
tst.pl r9,r0 ; test if exponent is zero
jpnz [blink] ; return if non-denormal result
bmsk r6,r7,30
lsr r3,r6,23
xor r0,r6,r7
sub_s r3,r3,24-22
j_s.d [blink]
bset r0,r0,r3
; If a denorm is produced, we have an exact result -
; no need for rounding.
.balign 4
.Ldenorm_sub:
sub r3,r6,1
lsr.f r3,r3,23
xor r0,r6,r7
neg_s r1,r3
asl.ne r4,r4,r3
lsr_s r12,r12,r1
add_s r0,r0,r4
j_s.d [blink]
add.ne r0,r0,r12
.balign 4
.Lsub_done_noshift:
add.f 0,r12,r12
btst.eq r4,0
bclr r4,r4,23
add r0,r7,r4
j_s.d [blink]
adc.ne r0,r0,0
.balign 4
.Lno_shiftdown:
add.f 0,r5,r5
btst.eq r0,0
cmp.eq r5,r5
j_s.d [blink]
add.cs r0,r0,1
.Lret_dbl1:
j_s.d [blink]
mov_l r0,r1
.balign 4
.Ldenorm_small_shift_dbl0:
sub.f r8,r8,1
bne.d .Lfixed_denorm_small_shift_dbl0
add_s r12,r12,1
brlt.d r10,0,.Lrsub
mov r5,0
.Ladd_dbl1_gt: ; both bit 23 of DBL0 and bit 0 of r5 are clear.
bmsk r2,r1,22
add_s r2,r2,r0
bbit0.d r2,23,.Lno_shiftdown_dbl1_gt
add_s r0,r1,r0
bic.f 0,r9,r0; check for overflow -> infinity; eq : infinity
bmsk r1,r2,22
lsr.ne.f r2,r2,2; cc: even ; hi: might round down
lsr.ne r1,r1,1
rcmp.hi r5,1; hi : round down
bclr.hi r0,r0,0
j_l.d [blink]
sub_s r0,r0,r1
.balign 4
.Lno_shiftdown_dbl1_gt:
add.f 0,r5,r5
btst.eq r0,0
cmp.eq r5,r5
j_s.d [blink]
add.cs r0,r0,1
ENDFUNC(__addsf3)
ENDFUNC(__subsf3)