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From: Jan Hubicka <hubicka@ucw.cz>
To: "d.g.gorbachev at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
Cc: gcc-bugs@gcc.gnu.org
Subject: Re: [Bug lto/47205] New: GCC emits optimized out noinline function
Date: Fri, 07 Jan 2011 12:48:00 -0000	[thread overview]
Message-ID: <20110107124715.GI20917@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <bug-47205-4@http.gcc.gnu.org/bugzilla/>

> extern int foo(void);
> 
> int main(void)
> {
>   return foo() * 0;
> }
This is because gimple part of optimizers for some reason leads to the following in the optimized dump:
main ()
{
<bb 2>:
  foo ();
  return 0;

}
and only RTL optimizers do the trick.  
This is weird since pure/const detect function as pure (seen in pure-const dump)

Read info for foo/2  const nothrow
  pure const state: const
  previously known state: const

but tree-ssa-dce apparently fails to remove the statement.  I guess it is
confused by lack of return value.  I will take a look.  But this is
tree-optimization bug.

Honza


  reply	other threads:[~2011-01-07 12:47 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-07 11:45 d.g.gorbachev at gmail dot com
2011-01-07 12:48 ` Jan Hubicka [this message]
2011-01-07 12:52 ` [Bug lto/47205] " hubicka at ucw dot cz
2011-01-07 12:58 ` [Bug tree-optimization/47205] " hubicka at gcc dot gnu.org
2011-01-07 12:59 ` hubicka at gcc dot gnu.org
2021-08-30  4:54 ` pinskia at gcc dot gnu.org

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