[Bug rtl-optimization/17838] spills are not re-used

[tstdenis at elliptictech dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17838

--- Comment #9 from Tom St Denis <tstdenis at elliptictech dot com> 2011-11-10 19:28:33 UTC ---
(In reply to comment #7)
> (In reply to comment #6)
> > Created attachment 25751 [details]
> > Another test case
> > 
> > Another example using 
> > 
> > gcc version 4.6.1 20110908 (Red Hat 4.6.1-9) (GCC) 
> > 
> > The function when compiled with "-m32 -O3" uses way more stack than it should. 
> > It's like it's putting the fp_int.dp[] array on the stack...
> > 
> > I can confirm this is a problem on 32/64 and ARM as well.
> 
> That is a different issue dealing with memcpy works (or does not get
> optimized).  File a different bug.

How the hell am I supposed to know that?  Maybe the GCC team should clean up
their stack spills once and for all.  I'm sure $OBSCURE_PLATFORM_NAME or
$WONDEROUS_NEW_TREE_REPRESENTATION can wait.

I actually have a different routine [fp_mul_comba_small_set.c] from
TomsFastMath that does use memcpy, has the same style of unrolled multipliers,
and does not have this problem.

I can file a new bug if you want, but as a user of GCC I'm not meant to
understand the ins-and-outs of the depths of the compiler.  I actually did
search for stack-waste instead of just blindly filing a new report...

/rant