From: Ian Lance Taylor <iant@google.com>
To: "Maciej W. Rozycki" <macro@mips.com>
Cc: binutils@sources.redhat.com, "Maciej W. Rozycki" <macro@linux-mips.org>
Subject: Re: [RFD] MIPS/gas: Optimisation cannot be set to 0
Date: Fri, 09 Nov 2007 16:10:00 -0000 [thread overview]
Message-ID: <m3y7d7jt8z.fsf@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.61.0711061718210.23904@perivale.mips.com>
"Maciej W. Rozycki" <macro@mips.com> writes:
> Wed Feb 12 14:36:29 1997 Ian Lance Taylor <ian@cygnus.com>
>
> * config/tc-mips.c (md_parse_option): When debugging, set
> mips_optimize to 1, not 0.
My vague recollection of the problem is that at least at that time gcc
would always pass a -O option to the assembler. When not optimizing,
it would pass -O0. However, inserting NOPs for MIPS variants which do
not need them does not help debugging.
Clearly failing to provide a way to set mips_optimize to 0 was an
oversight.
> I have no strong preference, but I think gas should have a mode where its
> input is assembled intact. And swapping branches may produce surprising
> interactions with debugging information. I am therefore in favour to the
> first proposal above, but I would like to hear from the others.
I'm not sure I see the relevance of "assembled intact." The source is
assembled just as the user specified with -O1. -O1 simply inhibits
adding additional unnecessary nop instructions--nop instructions that
were required for MIPS ISA I but not for later ISAs.
At -O1 branches are not swapped, so debugging is not impaired.
I agree there should be a way to set mips_optimize to 0, but we should
ensure that gcc -O0 does not set mips_optimize to 0 when assembling.
Ian
next prev parent reply other threads:[~2007-11-09 16:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-09 13:52 Maciej W. Rozycki
2007-11-09 15:56 ` Thiemo Seufer
2007-11-09 16:10 ` Ian Lance Taylor [this message]
2007-11-09 17:35 ` Maciej W. Rozycki
2007-11-09 17:56 ` Paul Koning
2007-11-09 18:31 ` Maciej W. Rozycki
2007-11-11 11:24 ` Richard Sandiford
2007-11-12 18:07 ` Maciej W. Rozycki
2007-11-12 19:39 ` Richard Sandiford
2007-11-14 17:57 ` Thiemo Seufer
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