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From: "zack at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/17958] New: expand_divmod fails to optimize division of 64-bit quantity by small constant when BITS_PER_WORD is 32
Date: Tue, 12 Oct 2004 22:48:00 -0000 [thread overview]
Message-ID: <20041012224816.17958.zack@gcc.gnu.org> (raw)
expand_divmod cannot optimize code such as
long long div10(long long n) { return n / 10; }
when BITS_PER_WORD is 32. A call to __divdi3 gets generated. By contrast, when
BITS_PER_WORD is 64, this is optimized to a multiply and a shift. I noticed
this problem on powerpc32, but it ought to affect any 32-bit target.
--
Summary: expand_divmod fails to optimize division of 64-bit
quantity by small constant when BITS_PER_WORD is 32
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P2
Component: rtl-optimization
AssignedTo: roger at eyesopen dot com
ReportedBy: zack at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: powerpc-*-*
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17958
next reply other threads:[~2004-10-12 22:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-12 22:48 zack at gcc dot gnu dot org [this message]
2004-10-12 22:55 ` [Bug middle-end/17958] " pinskia at gcc dot gnu dot org
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