Re: change the location_t type, DECL_SOURCE_LINE etc

[Fergus Henderson <fjh at cs dot mu dot OZ dot AU>]

On 02-Dec-2002, Per Bothner <per@bothner.com> wrote:
> To reduce space usage we have to replace the filename by an index
> in a 'line_table'.  We also have to use bit fields in order to squeeze
> everything into 32 bits.  This means a limited number of different
> file names, and a limited range on line and column numbers.  However,
> it is not quite a limited as the 14 and 8 suggest, since we can
> have multiple 'line_table' entries for the same filename, but with
> different line and column base values.  Thus:
> 
> /* The data structure used to record a location in a translation unit.  */
> struct location_s GTY (())
> {
>    /* An index into line_table. */
>    unsigned int file_index : 10;
> 
>    /* The source line, relative to line_table[file_index].line_base. */
>    unsigned int rline : 14;
> 
>    /* The source column, relative to line_table[file_index].column_base. */
>    unsigned int rcolumn : 8;
> };

The C code generated by the Mercury compiler is going to overflow
those limits, I think.

Currently the longest C file generated by the Mercury compiler
is about 600,000 lines long (20,000,000 bytes).
The longest line is about 2300 characters.
There are up to about 750 header files.

-- 
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.