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authorimp <imp@FreeBSD.org>1999-03-01 06:27:31 +0000
committerimp <imp@FreeBSD.org>1999-03-01 06:27:31 +0000
commita33e5716f56ac0e54bf6051df6b0889247455209 (patch)
tree7416fec1b45002adff46133f13305dbd48bfd06a /contrib/libgmp/mpn/mips3/README
parent7fbf66313a44405a9d9a78c90611dad3c0597620 (diff)
downloadFreeBSD-src-a33e5716f56ac0e54bf6051df6b0889247455209.zip
FreeBSD-src-a33e5716f56ac0e54bf6051df6b0889247455209.tar.gz
Import mips2 and mips3 files from the 2.0.2 gmp distribution.
Approved by: markm
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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
+ possible latencies.
+
+STATUS
+
+Good...
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