Re: sizeof bool > sizeof int ?!?

[Per Bothner <bothner at cygnus dot com>]

The last time this came up, I lobbied for making sizeof(bool)
be 1 byte.  I see little reason for making sizeof(bool) > sizeof(short),
yet no-one argues for making sizeof(short) be 4 or 8 on any system,
even though it would be consistent with standards, and probably
more efficient.  The thing is that people *expect* sizeof(short)
to be 2, and changing that would break some code, and make other
code be unacceptably bloated.

Well, guess what?  I think most programmers *expect* sizeof(bool)
to be 1 - but we are violating their very reasonable expectation.

What we really want is for bool in arrays and structs to be 1 byte,
but bool as a standalone variable to be whatever is fastest,
or at least the compiler to act as if it were.  Last time around
I was told that Gcc actualy does have the mechanism for something
like that - basically use full-words registers for bool local
variables.  It was also suggested this would remove most of
the speed penalty of making bool be 1 byte.

Note we also have a framework for making incomaptible changes:
-fnew-abi.  So I see no reason for not changing sizeof(bool) to 1
in the new ABI.  (This assumes the back-end people can help
with whatever magic flags are needed to making this faster.)

	--Per Bothner
Cygnus Solutions     bothner@cygnus.com     http://www.cygnus.com/~bothner