After the RA phase of ego, a procedure may put single-word and
double-word values in the same reg_float. Then ncg will use both
LOCAL and DLOCAL tokens at the same offset.
I add isregvar_size() to ncg. It receives the size of the LOCAL or
DLOCAL token, and picks the register of the correct size. This fixes
a problem where ncg got the wrong-size register and corrupted the
stack. This problem caused one of my test programs to segfault from
stack underflow.
Also adjust how fixregvars() handles both sizes.
The new feature "reglap" allows two sizes of floating-point register
variables (reg_float), if each register overlaps a single register of
the other size. PowerPC ncg uses reglap to define 4-byte instances
of f14 to f31 that overlap the 8-byte instances.
When ncgg sees the definition of fs14("f14")=f14, it removes the
8-byte f14 from its rvnumbers array, and adds the 4-byte fs14 in its
place. Later, when ncg puts a variable in fs14, if it is an 8-byte
variable, then ncg switches to the 8-byte f14. The code has
/* reglap */ comments in util/ncgg or #ifdef REGLAP in mach/proto/ncg
reglap became necessary because my commit a20b87c caused PowerPC ego
to allocate reg_float in both 4-byte and 8-byte sizes.
