1Copyright 1996 Free Software Foundation, Inc. 2 3This file is part of the GNU MP Library. 4 5The GNU MP Library is free software; you can redistribute it and/or modify 6it under the terms of the GNU Lesser General Public License as published by 7the Free Software Foundation; either version 3 of the License, or (at your 8option) any later version. 9 10The GNU MP Library is distributed in the hope that it will be useful, but 11WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 12or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 13License for more details. 14 15You should have received a copy of the GNU Lesser General Public License 16along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. 17 18 19 20 21 22This directory contains mpn functions optimized for MIPS3. Example of 23processors that implement MIPS3 are R4000, R4400, R4600, R4700, and R8000. 24 25RELEVANT OPTIMIZATION ISSUES 26 271. On the R4000 and R4400, branches, both the plain and the "likely" ones, 28 take 3 cycles to execute. (The fastest possible loop will take 4 cycles, 29 because of the delay insn.) 30 31 On the R4600, branches takes a single cycle 32 33 On the R8000, branches often take no noticable cycles, as they are 34 executed in a separate function unit.. 35 362. The R4000 and R4400 have a load latency of 4 cycles. 37 383. On the R4000 and R4400, multiplies take a data-dependent number of 39 cycles, contrary to the SGI documentation. There seem to be 3 or 4 40 possible latencies. 41 424. The R1x000 processors can issue one floating-point operation, two integer 43 operations, and one memory operation per cycle. The FPU has very short 44 latencies, while the integer multiply unit is non-pipelined. We should 45 therefore write fp based mpn_Xmul_1. 46 47STATUS 48 49Good... 50