+ For each described register, if 'size' is larger than the
+ register's size, the register's value is assumed to be stored in
+ the first N (where N is the register size) bytes at the current
+ offset. The remaining 'size' - N bytes are filled with zeroes by
+ 'regcache_collect_regset' and ignored by other consumers.
+
+ If 'size' is smaller than the register's size, only the first
+ 'size' bytes of a register's value are assumed to be stored at
+ the current offset. 'regcache_collect_regset' copies the first
+ 'size' bytes of a register's value to the output buffer.
+ 'regcache_supply_regset' copies the bytes from the input buffer
+ into the first 'size' bytes of the register's value leaving the
+ remaining bytes of the register's value unchanged. Frame caches
+ read the 'size' bytes from the stack frame and zero extend them
+ to generate the register's value.
+