Re: [rfa] Change line to long

[Kevin Buettner <kevinb at cygnus dot com>]

On Feb 1, 12:36pm, Michael Elizabeth Chastain wrote:

> Kevin Buettner:
> > Is there any reason not to make the type of ``line'' an unsigned long?
> 
> Looking at 'struct symbol', the type of ``line'' is an unsigned short
> so that it will pack well with 'namespace' and 'aclass', which are of
> type BYTE_BITFIELD.
> 
> However, some time ago, BYTE_BITFELD was nerfed anyways.  So I believe
> that sizeof(symbol) will not increase if you change ``line'' to a
> 32-bit type.
> 
> I like unsigned int better than unsigned long because it takes less
> space on 64-bit hosts.

Your concerns about the amount of space required by these data
structures are certainly valid.  One of gdb's current problems
is its memory footprint.

As a rule of thumb, the type of the "thing" in the data structure
should be at least as wide as any of the inputs used to populate the
data structure.  In this case, the rule would mean that the type of
``line'' should be at least as wide as an unsigned long (because
that's what is used in dwarf2read.c).

However, from a more practical perspective, having the type of line
be either a signed or unsigned 32-bit integer is probably more than
adequate.  (These represent line numbers and it seems unlikely to
me that anyone would want to debug a file with over 2 billion lines
in it.)

I'll leave it up to Andrew to decide what to do about it.  If gdb had
something like uint32_t available, I'd suggest using that.

Kevin