I just tried to compile Fedora development package xorg-x11-6.8.2-54
with a special non-standard version of the usual GNU C compiler.

The compiler said

pm2v_dac.c:224: warning: array subscript out of range
pm2v_dac.c:225: warning: array subscript out of range
pm2v_dac.c:226: warning: array subscript out of range

The source code is

	pReg->DacRegs[PM2VDACRDDClk0PreScale] = m;

but

../BUILD/xorg-x11-6.8.2/xc/programs/Xserver/hw/xfree86/drivers/glint/glint_regs.h:#define
PM2VDACRDDClk0PreScale                                               0x201

and

../BUILD/xorg-x11-6.8.2/xc/programs/Xserver/hw/xfree86/drivers/glint/glint.h:
CARD32 DacRegs[0x100];

Suggest code rework. Similar fun and games at 

pm2v_dac.c:332: warning: array subscript out of range
pm2v_dac.c:333: warning: array subscript out of range
pm2v_dac.c:334: warning: array subscript out of range
pm2v_dac.c:399: warning: array subscript out of range
pm2v_dac.c:399: warning: array subscript out of range
pm2v_dac.c:401: warning: array subscript out of range
pm2v_dac.c:401: warning: array subscript out of range
pm2v_dac.c:403: warning: array subscript out of range
pm2v_dac.c:403: warning: array subscript out of range