RFR(S): 8213419: C2 may hang in MulLNode::Ideal()/MulINode::Ideal() with gcc 8.2.1

[dean.long at oracle.com]

OK, I just wanted to make sure the code was doing what you intended.  
Isn't this still undefined behavior:

jint abs_con = uabs(con);


if the unsigned value is too big to fit in a signed int?

dl

On 11/7/18 4:22 AM, Roland Westrelin wrote:
> Hi Dean,
>
>> Hi Roland.  Can you explain what happens for INT_MIN now?  It looks like
>> uabs() will return a negative number and sign_flip will be set to false.
> Thanks for looking at this.
>
> sign_flip is needed to negate the result of the shift. Multiplying by
> INT_MIN only has 2 results: INT_MIN (INT_MIN * 1, INT_MIN * -1) or 0
> (INT_MIN multiplied by any other value). So negation is useless because
> -INT_MIN = INT_MIN.
>
> Roland.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/attachments/20181107/d40ddf36/attachment-0001.html>