Message 58566 - Python tracker

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Author	gvanrossum
Recipients	donmez, gvanrossum, loewis
Date	2007-12-13.19:16:37
SpamBayes Score	0.0042796605
Marked as misclassified	No
Message-id	<ca471dc20712131116g55920ad1o2e143f54bca319a5@mail.gmail.com>
In-reply-to	<1197573007.63.0.516495308629.issue1608@psf.upfronthosting.co.za>

Content
> if you can give me a sample testcase I can bug GCC developers, this > doesn't look good from GCC side at all. Btw from my limited C knowledge > marking variables would volatile would prevent optimizations of them. The example would be something like void foo(ssize_t x) { if (x >= 0) { if (x+x < 0) printf("Overflow\n"); } } main() { foo(2147483647); } This should print "Overflow" but won't if the evil optimization triggers. (However you may have to tweak the example program so the compiler can't inline the argument to foo.)

> if you can give me a sample testcase I can bug GCC developers, this
> doesn't look good from GCC side at all. Btw from my limited C knowledge
> marking variables would volatile would prevent optimizations of them.

The example would be something like

void foo(ssize_t x)
{
  if (x >= 0) {
    if (x+x < 0) printf("Overflow\n");
  }
}

main()
{
  foo(2147483647);
}

This should print "Overflow" but won't if the evil optimization
triggers. (However you may have to tweak the example program so the
compiler can't inline the argument to foo.)

History
Date	User	Action	Args
2007-12-13 19:16:37	gvanrossum	set	spambayes_score: 0.00427966 -> 0.0042796605 recipients: + gvanrossum, loewis, donmez
2007-12-13 19:16:37	gvanrossum	link	issue1608 messages
2007-12-13 19:16:37	gvanrossum	create