Why is the state of cache being changed by regcache_observer_notify_target() ?

["Kalpana Ramamurthy" <kal_pana@hotmail.com>]

I am changing a register like this :
$sp = (long long *)$pa

When value_assign() is called in valops.c, it goes to put_frame_register() 
to set the modified
contents of register SP. While doing this, it sets the registers_valip_p to 
1 in
register_raw_write() after copying over the modified values in the buffer to 
the regcache.

memcpy (register_buffer (regcache, regnum), buf, 
regcache->descr->sizeof_register[regnum]) ;
regcache->register_valid_p[regnum] = 1 ;

But soon after in value_assign(), it calls for 
observer_notify_target_changed() which in turn
calls regcache_observer_target_changed(). This calls for register_changed() 
that immediately
resets the value of register_valid_p to 0. And when register_valid_p is set 
to 0, it indicates that
it is not cached but is fetchable and hence tries to fetch the target 
registers again. Something
which I cannot understand gets messed up after that.

But if I comment out the call to observer_notify_target_changed() in 
value_assign(), everything
works fine and the value of $sp is changed as per what I want.

Why is the regcache_observer_target_changed() changing the values of 
register_valid_p as soon as its set earlier ?

Kalpana
===

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