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[perl #30123] foreach ("", "a".."zzzzzz") confuses range optimizer
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From:
Michael G Schwern
Date:
June 9, 2004 01:57
Subject:
[perl #30123] foreach ("", "a".."zzzzzz") confuses range optimizer
Message ID:
rt-3.0.9-30123-89958.4.17331979991744@perl.org
# New Ticket Created by Michael G Schwern
# Please include the string: [perl #30123]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org:80/rt3/Ticket/Display.html?id=30123 >
This is a bug report for perl from schwern@pobox.com,
generated with the help of perlbug 1.34 running under perl v5.8.1.
-----------------------------------------------------------------
[Please enter your report here]
A co-worker exhausted his machine's memory trying to compile this:
for ( '', 'a'..'zzzzzzz' ) {}
B::Deparse (using 'zzz') reveals that Perl is trying to build that
entire list in memory. The range optimizer seems to only kick in when
there's nothing but a range in there.
Our work around is:
for ( $i = ""; $i ne "aaa"; ($i = $i ? ++$i : "a") ) { print $i }
Bug/optimizer-miss appears in 5.6.1, 5.8.1 and 5.8.3.
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=low
---
Site configuration information for perl v5.8.1:
Configured by root at Fri Sep 12 19:46:46 PDT 2003.
Summary of my perl5 (revision 5.0 version 8 subversion 1 RC3) configuration:
Platform:
osname=darwin, osvers=7.0, archname=darwin-thread-multi-2level
uname='darwin hampsten 7.0 darwin kernel version 6.0: fri jul 25 16:58:41 pdt 2003; root:xnu-344.frankd.rootsxnu-344.frankd~objrelease_ppc power macintosh powerpc '
config_args='-ds -e -Dprefix=/usr -Dccflags=-g -pipe -Dldflags=-Dman3ext=3pm -Duseithreads -Duseshrplib'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-g -pipe -pipe -fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -I/usr/local/include',
optimize='-Os',
cppflags='-no-cpp-precomp -g -pipe -pipe -fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -I/usr/local/include'
ccversion='', gccversion='3.3 20030304 (Apple Computer, Inc. build 1495)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=4321
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=8
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=8, prototype=define
Linker and Libraries:
ld='MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags ='-L/usr/local/lib'
libpth=/usr/local/lib /usr/lib
libs=-ldbm -ldl -lm -lc
perllibs=-ldl -lm -lc
libc=/usr/lib/libc.dylib, so=dylib, useshrplib=true, libperl=libperl.dylib
gnulibc_version=''
Dynamic Linking:
dlsrc=dl_dyld.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
cccdlflags=' ', lddlflags='-bundle -undefined dynamic_lookup -L/usr/local/lib'
Locally applied patches:
RC3
---
@INC for perl v5.8.1:
/sw/lib/perl5/5.8.1/darwin-thread-multi-2level
/sw/lib/perl5/5.8.1
/sw/lib/perl5
/sw/lib/perl5/darwin
/System/Library/Perl/5.8.1/darwin-thread-multi-2level
/System/Library/Perl/5.8.1
/Library/Perl/5.8.1/darwin-thread-multi-2level
/Library/Perl/5.8.1
/Library/Perl
/Network/Library/Perl/5.8.1/darwin-thread-multi-2level
/Network/Library/Perl/5.8.1
/Network/Library/Perl
.
---
Environment for perl v5.8.1:
DYLD_LIBRARY_PATH (unset)
HOME=/Users/schwern
LANG (unset)
LANGUAGE (unset)
LC_ALL=C
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/Users/schwern/bin:/usr/local/bin:/Users/schwern/bin:/usr/local/bin:/sw/bin:/sw/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/schwern:/usr/X11R6/bin:.:.
PERL5LIB=/sw/lib/perl5:/sw/lib/perl5/darwin
PERL_BADLANG (unset)
SHELL=/sw/bin/bash
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[perl #30123] foreach ("", "a".."zzzzzz") confuses range optimizer
by Michael G Schwern