64-bit ptrs vs unsigned preservation

[quanstro gmail, 2012-10-11 13:27:06]

On 2012/10/11 13:23:48, quanstro wrote:

a little longer description.  on plan 9 i found that for
an unsigned-preserving compiler with larger pointers than
integers, small negative p.y would result in a bad pointer.
since the u32int would not be signed extended, it could have
a value like 0x00000000fffffff4, which is no longer small or
negative.

[rsc, 2012-10-21 16:08:53]

*** Submitted as http://code.google.com/p/plan9port/source/detail?r=51f0d82e6132
***

libmemdraw: fix int size bug

R=rsc, quanstro
CC=plan9port.codebot
http://codereview.appspot.com/6657043

Committer: Russ Cox <rsc@swtch.com>

[rsc, 2012-10-21 16:08:55]

LGTM