From: Toon Moene <toon@moene.indiv.nluug.nl>
To: law@cygnus.com
Cc: egcs@cygnus.com
Subject: Re: my EGCS status (really Fortran patches)
Date: Wed, 22 Oct 1997 22:55:00 -0000 [thread overview]
Message-ID: <9710230552.AA21715@moene.indiv.nluug.nl> (raw)
In-Reply-To: <4712.877581304@hurl.cygnus.com>
Jeff,
L$0009
fldds,ma 8(0,%r26),%fr24
fldds,ma 8(0,%r24),%fr23
fldds 0(0,%r25),%fr22
fmpy,dbl %fr24,%fr23,%fr23
fldds,ma 8(0,%r23),%fr25
fsub,dbl %fr22,%fr23,%fr22
fmpy,dbl %fr22,%fr25,%fr22
fstds,ma %fr22,8(0,%r25)
fldds,ma 8(0,%r22),%fr23
fldds 0(0,%r20),%fr22
fmpy,dbl %fr24,%fr23,%fr24
fsub,dbl %fr22,%fr24,%fr22
fmpy,dbl %fr22,%fr25,%fr22
addib,>= -1,%r28,L$0009
fstds,ma %fr22,8(0,%r20)
> Now, I don't actually know if one version executes any
> faster than the other -- this is just something I noticed
> when looking for why tomcatv ran 10% slower with the USE
> patch.
[ I once saw HP-PA assembler before, about a year ago, because
someone complained to the g77-bug list that he couldn't get Fortran
code with assigned goto's to assemble - turned out the HP assembler
can't cope with forward labels in instructions other than jumps. So
take this with a grain of salt ]
I gather, from looking at this code that instructions ending in .ma
do (implicit) post-increment addressing ? That would explain a
lot: The instructions normally associated with updating address
registers can be interspersed between the floating point ops, which
is a win on a CPU that has separate integer and floating point
units. You lose this advantage when these integer instructions
aren't explicit. On the m68k post-increment addressing is a real
win, because you're actually saving instructions. Seems that HP
wanted the best of both worlds ... and lost (wonder how they solve
this themselves ...)
I don't see a simple way out of this.
HTH,
Toon.
next prev parent reply other threads:[~1997-10-22 22:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <9710211752.AA19479@moene.indiv.nluug.nl>
1997-10-22 21:33 ` Jeffrey A Law
1997-10-22 22:55 ` Toon Moene [this message]
1997-10-22 23:26 ` Jeffrey A Law
1997-10-23 0:47 ` Jeffrey A Law
1997-10-23 10:45 ` Toon Moene
1997-10-23 11:04 ` Jeffrey A Law
1997-10-23 12:18 ` Joe Buck
1997-10-24 22:37 ` -frerun-loop Jeffrey A Law
1997-10-22 22:33 ` my EGCS status (really Fortran patches) Jeffrey A Law
1997-10-26 9:18 ` Jeffrey A Law
1997-10-27 16:30 ` Jim Wilson
1997-10-27 15:54 ` Jeffrey A Law
1997-10-27 17:21 ` Jim Wilson
1997-10-28 12:35 ` Jeffrey A Law
1997-10-28 12:35 ` Toon Moene
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