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From: fotland@hpihoah.HP.COM (Dave Fotland)
Newsgroups: comp.arch
Subject: Re: Common Compilers for benchmarks (was: Re: benchmarking)
Message-ID: <4420008@hpihoah.HP.COM>
Date: 2 Nov 88 01:42:10 GMT
References: <26627@ucbvax.BERKELEY.EDU>
Organization: Hewlett Packard, Cupertino
Lines: 30

At HP we use the precision architecture for machines running MPE, a
commercial operating system, as well as Unix.  We studied the impact on
COBOL and database manager code extensively when we were designing the
architecture.  Support includes:

Decimal Correct (DCOR and IDCOR) to correct 8 decimal digits in one cycle
	when doing decimal arithmetic.  This allows decimal arithmetic
	at 2 instructions per 8 digits (an add and a correct).

Store bytes (STBYS) This implements the beginning and end cases in byte
	string moves, storing zero to 4 bytes depending on the alignment
	of the address and whether the beginning case or end case is
	specified.  Fast byte string moves are very important in
	commercial applications.

Unit instructions and conditions.  For example, Unit Xor with the condition
	Some Digit Zero can do a very fast BCD string search (8 digits
	per instruction).  Specifying Some Byte Zero gets you a fast
	charcter string search.

Add and trap on overflow (ADDO) supports fast range checking.

The 3/87 HP Journal and the 1/86 HP Journal have articles on how these
instructions are used by the compilers.  COBOL runs extremely well on
HP-PA.  Most benchmarks shown in the article run faster on an HP-PA
machine than on a CISC machine with the same MIPS rating.

-David Fotland

(The HP-PA instruction set manual is part number 09740-90014)