Copyright 1996 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP 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
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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License for more details.
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This directory contains mpn functions optimized for MIPS3. Example of
processors that implement MIPS3 are R4000, R4400, R4600, R4700, and R8000.
RELEVANT OPTIMIZATION ISSUES
1. On the R4000 and R4400, branches, both the plain and the "likely" ones,
take 3 cycles to execute. (The fastest possible loop will take 4 cycles,
because of the delay insn.)
On the R4600, branches takes a single cycle
On the R8000, branches often take no noticable cycles, as they are
executed in a separate function unit..
2. The R4000 and R4400 have a load latency of 4 cycles.
3. On the R4000 and R4400, multiplies take a data-dependent number of
cycles, contrary to the SGI documentation. There seem to be 3 or 4