xsrc/50353: Stippled regions rendered as black on i82810e using xf86-video-intel built with GCC 4.8.x

[jdbaker%mylinuxisp.com@localhost]

>Number:         50353
>Category:       xsrc
>Synopsis:       Stippled regions rendered as black on i82810e using xf86-video-intel built with GCC 4.8.x
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    xsrc-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Oct 21 17:05:00 +0000 2015
>Originator:     John D. Baker
>Release:        NetBSD/i386-6.99.48 and later, following import of GCC 4.8.3+
>Organization:
>Environment:
NetBSD plexor 7.99.21 NetBSD 7.99.21 (PLEXOR) #6: Wed Oct 21 00:37:24 CDT 2015  sysop%skuld.technoskunk.fur@localhost:/d0/build/nbsd-tst/obj/i386/sys/arch/i386/compile/PLEXOR i386

>Description:
As described in the thread starting here:

  https://mail-index.netbsd.org/current-users/2014/08/05/msg025522.html

Machines with i82810e graphics using "xf86-video-intel" ("intel_drv.so")
built with GCC 4.8.[345] render "stippled" regions (alternating
foreground/background colors) as black.  Examples include:

  X server root window when using "-retro" option
  XTerm and XConsole scroll bars
  twm active window title bars/inactive window frames
  root window after 'xsetroot -mod x y ...' command

Back when GCC 4.5.x was still available, building "intel_drv.so" with
GCC 4.5 (modulo disabling SNA to work around an ICE) resulted in
correctly-rendered stippled regions.

On the off chance that compiler optimization was doing something
untoward, I built the driver with:

  COPTS+=-O0

but the behavior did not change.
>How-To-Repeat:
Install any NetBSD from 6.99.48 or later, built with GCC 4.8.x, on a
machine using i82810e graphics.

  $ startx -- -retro

Observe black screen instead of X root weave pattern.  XTerms have black
scroll-bar regions, 'twm' active window has black rectangle instead of
white/green lattice stippling in title bar.

If you roll back to a point at which things could still be built with
GCC 4.5.x, build "intel_drv.so", copy it into the GCC-4.8.x-built
system and re-start X.  Stippled regions now render properly.
>Fix: