I was reviewing some back end code that handles integer values of various
sizes, and got confused reading about CONST_INT and CONST_DOUBLE.
It's pretty clear that CONST_DOUBLE is used for values bigger than
HOST_WIDE_INT. But the description of INTVAL is contradictory. In some
places, it states that its type is HOST_WIDE_INT; in others it says that it it
"int". For example, in section 17.6 of the internals manual:
Be careful when doing this, because the result of INTVAL is an integer on the
host machine. If the host machine has more bits in an int than the target
machine has in the mode in which the constant will be used, then some of the
bits you get from INTVAL will be superfluous.
A related problem is that it isn't clearly stated what the properties of
HOST_WIDE_INT are. Judging by hwint.h, it is always specifically a 64 bit
integer. If that is intended to be the case, it would be good for that to be
documented. Alternatively, if the intent is that it is at least 64 bits but
might be bigger, that should be stated. As it stands, I have some code I need
to repair because it picks apart integer constants from INTVAL in a way that's
incorrect if a 64-bit value is passed.
paul
