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| author | Richard Henderson <rth@twiddle.net> | 2013-02-26 15:49:51 -0800 |
|---|---|---|
| committer | Richard Henderson <rth@twiddle.net> | 2013-03-06 07:47:25 -0800 |
| commit | fe62ba37a30b83be7e2a63b667fd519ca7e1b28d (patch) | |
| tree | dc7b0c9c4cfbcbe6cac66f4b07a6c7b1a23701b5 | |
| parent | 21e31515a694b966f5df11ec2aee6c51b3fd0a96 (diff) | |
| download | glibc-fe62ba37a30b83be7e2a63b667fd519ca7e1b28d.tar.gz glibc-fe62ba37a30b83be7e2a63b667fd519ca7e1b28d.tar.xz glibc-fe62ba37a30b83be7e2a63b667fd519ca7e1b28d.zip | |
arm: Add optimized submul_1
Written from scratch rather than copied from GMP, due to LGPL 2.1 vs GPL 3, but tested with the GMP testsuite. This is 50% faster than the generic code as measured on Cortex-A15. It is 25% slower than the current GMP routine on the same core.
| -rw-r--r-- | ports/ChangeLog.arm | 1 | ||||
| -rw-r--r-- | ports/sysdeps/arm/submul_1.S | 68 |
2 files changed, 69 insertions, 0 deletions
diff --git a/ports/ChangeLog.arm b/ports/ChangeLog.arm index a701215024..9470af2414 100644 --- a/ports/ChangeLog.arm +++ b/ports/ChangeLog.arm @@ -1,5 +1,6 @@ 2013-03-06 Richard Henderson <rth@redhat.com> + * sysdeps/arm/submul_1.S: New file. * sysdeps/arm/addmul_1.S: New file. * sysdeps/arm/armv6t2/ffs.S: New file. * sysdeps/arm/armv6t2/ffsll.S: New file. diff --git a/ports/sysdeps/arm/submul_1.S b/ports/sysdeps/arm/submul_1.S new file mode 100644 index 0000000000..3805eca9be --- /dev/null +++ b/ports/sysdeps/arm/submul_1.S @@ -0,0 +1,68 @@ +/* mpn_submul_1 -- multiply and subtract bignums. + Copyright (C) 2013 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library. If not, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + + .syntax unified + .text + +@ cycles/limb +@ StrongArm ? +@ Cortex-A8 ? +@ Cortex-A9 ? +@ Cortex-A15 4 + +/* mp_limb_t mpn_submul_1(res_ptr, src1_ptr, size, s2_limb) */ + +ENTRY (__mpn_submul_1) + push { r4, r5, r6, r7 } + cfi_adjust_cfa_offset (16) + cfi_rel_offset (r4, 0) + cfi_rel_offset (r5, 4) + cfi_rel_offset (r6, 8) + cfi_rel_offset (r7, 12) + + ldr r6, [r1], #4 + ldr r7, [r0] + mov r4, #0 /* init carry in */ + b 1f +0: + ldr r6, [r1], #4 /* load next ul */ + adds r5, r5, r4 /* (lpl, c) = lpl + cl */ + adc r4, ip, #0 /* cl = hpl + c */ + subs r5, r7, r5 /* (lpl, !c) = rl - lpl */ + ldr r7, [r0, #4] /* load next rl */ + it cc + addcc r4, r4, #1 /* cl += !c */ + str r5, [r0], #4 +1: + umull r5, ip, r6, r3 /* (hpl, lpl) = ul * vl */ + subs r2, r2, #1 + bne 0b + + adds r5, r5, r4 /* (lpl, c) = lpl + cl */ + adc r4, ip, #0 /* cl = hpl + c */ + subs r5, r7, r5 /* (lpl, !c) = rl - lpl */ + str r5, [r0], #4 + it cc + addcc r4, r4, #1 /* cl += !c */ + mov r0, r4 /* return carry */ + + pop { r4, r5, r6, r7 } + DO_RET (lr) +END (__mpn_submul_1) |