[Bug tree-optimization/49352] [4.7 Regression] -fcompare-debug failure with -O2 -ftree-vectorize

[irar at il dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49352

Ira Rosen <irar at il dot ibm.com> changed:

           What    |Removed                     |Added
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                 CC|                            |irar at il dot ibm.com

--- Comment #4 from Ira Rosen <irar at il dot ibm.com> 2011-06-10 12:22:17 UTC ---
(In reply to comment #3)
> Created attachment 24486 [details]
> gcc47-pr49352.patch
> 
> Rough patch I've been playing with.  There is no point testing gimple_code
> of use_stmt if it is GIMPLE_PHI, because phi is known to be a PHI.  

Right :)

> The patch
> attempts to only allow exactly one loop use stmt and use that stmt.  I had to
> drop the use_stmt != first_stmt test, otherwise the transformation wouldn't
> ever happen, not sure if you want to allow in that case another loop use (if
> yes, which one of the two do you want as loop_use_stmt?).

I think it's ok. Sorry, I can't remember why I added this condition. It doesn't
make sense to me now.

> 
> I also wonder if vect_is_slp_reduction should just return false; early if code
> is COND_EXPR, if for COND_EXPR def1 is not equal to phi I'm afraid it could be
> called.

Yes, probably a good idea.

Thanks,
Ira