Re: [patch] Work around gas .8byte bug.

[Mark Mitchell <mark at codesourcery dot com>]

Paul Brook wrote:

> This is a followup to a problem previously discovered by Mark.
> In summary gas doesn't properly handle negative integer constants larger than 
> the target word size. These can be generated by gcc 
>
> http://gcc.gnu.org/ml/gcc/2004-08/msg00690.html
>
> As stated in the above mesage, the prospects of fixing gas are not good, so 
> I'm proposing a workaround in gcc.
>
> The patch below changes default_assemble_integer to return false for simple 
> integer constants wider than the target word size. This will make gcc split 
> the constant into multiple word sized items.
>
> Other code paths (eg. CONST_DOUBLE) may also use .8byte, however they output 
> the values as positive hex constants. Moving the splitting logic into 
> assemble_integer_with_op would require and extra operand passing the operand 
> size. It seemed better to just fall back on the existing mechanisms for 
> handling large constants.
>
> In theory similar gas problems could be encountered for more complex 
> expressions (eg. .8byte foo + (-large_constant)). However I disbelieve that 
> any 32-bit target will generate these.
>
> Ok?
>  
OK, thanks.

--
Mark Mitchell
CodeSourcery, LLC
(916) 791-8304
mark@codesourcery.com