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Re: [Bug lto/47205] New: GCC emits optimized out noinline function
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: "d.g.gorbachev at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- Cc: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 7 Jan 2011 13:47:15 +0100
- Subject: Re: [Bug lto/47205] New: GCC emits optimized out noinline function
- References: <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