RFA: Don't destroy SCEV cache in copy-prop

[H.J. Lu]

On Fri, Dec 17, 2010 at 11:45 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Tue, Dec 7, 2010 at 5:34 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Sat, Dec 4, 2010 at 9:10 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Fri, Nov 26, 2010 at 7:03 AM, Michael Matz <matz@suse.de> wrote:
>>>> Hello,
>>>>
>>>> while working on something else I got a segfault in SCEV analysis because
>>>> it contained stale SSA names.  The reason is that copy-prop always DCEs
>>>> the propagated copies, invalidating SCEV entries referring to the LHS of
>>>> those.  We could either reset the SCEV cache (at the expense of having to
>>>> recompute it again), or simply not do DCE when we have loops.  I chose the
>>>> latter.
>>>>
>>>> I've also removed the superflous copy-prop in the graphite pipeline, it's
>>>> no use to run two copy-props next to each other.
>>>>
>>>> Unfortunately I don't have a testcase that fails with an unmodified GCC.
>>>>
>>>> Regstrapping on x86_64-linux (all langs + Ada) in progress.  Okay if that
>>>> passes?
>>>>
>>>>
>>>
>>> This caused:
>>>
>>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46799
>>>
>>
>> This also caused:
>>
>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46834
>>
>
> This also caused:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46994
>

This also caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46995


-- 
H.J.