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From: Joern Rennecke <amylaar@cambridge.redhat.com>
To: aoliva@redhat.com (Alexandre Oliva)
Cc: wilson@cygnus.com (Jim Wilson),
	gcc@gcc.gnu.org, gcc-patches@gcc.gnu.org, gdb@sources.redhat.com
Subject: Re: C++ ptrmemfun break if FUNCTION_BOUNDARY < 2 * BITS_PER_UNIT
Date: Mon, 09 Apr 2001 12:29:00 -0000	[thread overview]
Message-ID: <200104091927.f39JRtw00873@phal.cambridge.redhat.com> (raw)
In-Reply-To: <orofu6xfro.fsf@guarana.lsd.ic.unicamp.br>

 Is it safe to use arithmetic SHIFTs instead of letting the compiler
> choose them instead of DIVs and MULTs?  For some reason, on
> mn10300-elf, the div makes it to the generated code, which we
> certainly don't want.

A signed division is not a portable way to extract a bit.  And for
negative values, it just doesn't work.
Why don't you use an unsigned division or a logical shift?


  reply	other threads:[~2001-04-09 12:29 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <200104062005.NAA13684@wilson.cygnus.com>
2001-04-09  8:19 ` Alexandre Oliva
2001-04-09 12:29   ` Joern Rennecke [this message]
2001-04-09 13:12     ` Alexandre Oliva
2001-04-09 13:42       ` Joern Rennecke
2001-04-18  5:48       ` Richard Earnshaw
2001-04-18 12:11         ` Alexandre Oliva
2001-04-10  9:27   ` C++ ptrmemfun break if FUNCTION_BOUNDARY < 2 *BITS_PER_UNIT Mark Mitchell
2001-04-17 10:38   ` C++ ptrmemfun break if FUNCTION_BOUNDARY < 2 * BITS_PER_UNIT Andrew Cagney
2001-04-17 13:02     ` Daniel Berlin
2001-05-16  4:53       ` Jason Merrill
2001-05-16  7:18         ` Daniel Berlin

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