diff options
Diffstat (limited to 'ghc/rts/gmp/mpn/x86/pentium/diveby3.asm')
| -rw-r--r-- | ghc/rts/gmp/mpn/x86/pentium/diveby3.asm | 183 |
1 files changed, 0 insertions, 183 deletions
diff --git a/ghc/rts/gmp/mpn/x86/pentium/diveby3.asm b/ghc/rts/gmp/mpn/x86/pentium/diveby3.asm deleted file mode 100644 index dbac81642f..0000000000 --- a/ghc/rts/gmp/mpn/x86/pentium/diveby3.asm +++ /dev/null @@ -1,183 +0,0 @@ -dnl Intel P5 mpn_divexact_by3 -- mpn division by 3, expecting no remainder. -dnl -dnl P5: 15.0 cycles/limb - - -dnl Copyright (C) 2000 Free Software Foundation, Inc. -dnl -dnl This file is part of the GNU MP Library. -dnl -dnl The GNU MP Library is free software; you can redistribute it and/or -dnl modify it under the terms of the GNU Lesser General Public License as -dnl published by the Free Software Foundation; either version 2.1 of the -dnl License, or (at your option) any later version. -dnl -dnl The GNU MP Library is distributed in the hope that it will be useful, -dnl but WITHOUT ANY WARRANTY; without even the implied warranty of -dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU -dnl Lesser General Public License for more details. -dnl -dnl You should have received a copy of the GNU Lesser General Public -dnl License along with the GNU MP Library; see the file COPYING.LIB. If -dnl not, write to the Free Software Foundation, Inc., 59 Temple Place - -dnl Suite 330, Boston, MA 02111-1307, USA. - - -include(`../config.m4') - - -C mp_limb_t mpn_divexact_by3c (mp_ptr dst, mp_srcptr src, mp_size_t size, -C mp_limb_t carry); - -defframe(PARAM_CARRY,16) -defframe(PARAM_SIZE, 12) -defframe(PARAM_SRC, 8) -defframe(PARAM_DST, 4) - -dnl multiplicative inverse of 3, modulo 2^32 -deflit(INVERSE_3, 0xAAAAAAAB) - -dnl ceil(b/3), ceil(b*2/3) and floor(b*2/3) where b=2^32 -deflit(ONE_THIRD_CEIL, 0x55555556) -deflit(TWO_THIRDS_CEIL, 0xAAAAAAAB) -deflit(TWO_THIRDS_FLOOR, 0xAAAAAAAA) - - .text - ALIGN(8) - -PROLOGUE(mpn_divexact_by3c) -deflit(`FRAME',0) - - movl PARAM_SRC, %ecx - movl PARAM_SIZE, %edx - - decl %edx - jnz L(two_or_more) - - movl (%ecx), %edx - movl PARAM_CARRY, %eax C risk of cache bank clash here - - movl PARAM_DST, %ecx - subl %eax, %edx - - sbbl %eax, %eax C 0 or -1 - - imull $INVERSE_3, %edx, %edx - - negl %eax C 0 or 1 - cmpl $ONE_THIRD_CEIL, %edx - - sbbl $-1, %eax C +1 if edx>=ceil(b/3) - cmpl $TWO_THIRDS_CEIL, %edx - - sbbl $-1, %eax C +1 if edx>=ceil(b*2/3) - movl %edx, (%ecx) - - ret - - -L(two_or_more): - C eax - C ebx - C ecx src - C edx size-1 - C esi - C edi - C ebp - - pushl %ebx FRAME_pushl() - pushl %esi FRAME_pushl() - - pushl %edi FRAME_pushl() - pushl %ebp FRAME_pushl() - - movl PARAM_DST, %edi - movl PARAM_CARRY, %esi - - movl (%ecx), %eax C src low limb - xorl %ebx, %ebx - - sub %esi, %eax - movl $TWO_THIRDS_FLOOR, %esi - - leal (%ecx,%edx,4), %ecx C &src[size-1] - leal (%edi,%edx,4), %edi C &dst[size-1] - - adcl $0, %ebx C carry, 0 or 1 - negl %edx C -(size-1) - - -C The loop needs a source limb ready at the top, which leads to one limb -C handled separately at the end, and the special case above for size==1. -C There doesn't seem to be any scheduling that would keep the speed but move -C the source load and carry subtract up to the top. -C -C The destination cache line prefetching adds 1 cycle to the loop but is -C considered worthwhile. The slowdown is a factor of 1.07, but will prevent -C repeated write-throughs if the destination isn't in L1. A version using -C an outer loop to prefetch only every 8 limbs (a cache line) proved to be -C no faster, due to unavoidable branch mispreditions in the inner loop. -C -C setc is 2 cycles on P54, so an adcl is used instead. If the movl $0,%ebx -C could be avoided then the src limb fetch could pair up and save a cycle. -C This would probably mean going to a two limb loop with the carry limb -C alternately positive or negative, since an sbbl %ebx,%ebx will leave a -C value which is in the opposite sense to the preceding sbbl/adcl %ebx,%eax. -C -C A register is used for TWO_THIRDS_FLOOR because a cmp can't be done as -C "cmpl %edx, $n" with the immediate as the second operand. -C -C The "4" source displacement is in the loop rather than the setup because -C this gets L(top) aligned to 8 bytes at no cost. - - ALIGN(8) -L(top): - C eax source limb, carry subtracted - C ebx carry (0 or 1) - C ecx &src[size-1] - C edx counter, limbs, negative - C esi TWO_THIRDS_FLOOR - C edi &dst[size-1] - C ebp scratch (result limb) - - imull $INVERSE_3, %eax, %ebp - - cmpl $ONE_THIRD_CEIL, %ebp - movl (%edi,%edx,4), %eax C dst cache line prefetch - - sbbl $-1, %ebx C +1 if ebp>=ceil(b/3) - cmpl %ebp, %esi - - movl 4(%ecx,%edx,4), %eax C next src limb - - sbbl %ebx, %eax C and further -1 if ebp>=ceil(b*2/3) - movl $0, %ebx - - adcl $0, %ebx C new carry - movl %ebp, (%edi,%edx,4) - - incl %edx - jnz L(top) - - - - imull $INVERSE_3, %eax, %edx - - cmpl $ONE_THIRD_CEIL, %edx - movl %edx, (%edi) - - sbbl $-1, %ebx C +1 if edx>=ceil(b/3) - cmpl $TWO_THIRDS_CEIL, %edx - - sbbl $-1, %ebx C +1 if edx>=ceil(b*2/3) - popl %ebp - - movl %ebx, %eax - popl %edi - - popl %esi - popl %ebx - - ret - -EPILOGUE() |