Re: [LTO][PATCH] Fix long double precision problem

[Mark Mitchell <mark@codesourcery.com>]

Kenneth Zadeck wrote:

>> I think for ia64-hpux, you can use both TFmode and XFmode so maybe
>> this is not going to work for that.
>>
>> --Pinski
>>   
> is the right solution to just serialize the size and restore it from that?

Yes, and that's what the current code is doing; it looks at
DW_AT_bit_size in the DWARF information to determine how many bits to
use.  If that's not sufficient because, for example, DW_AT_bit_size is
the number of bits consumed in memory, but TYPE_PRECISION is supposed to
be the number of bits of useful data, then we should add a
DW_AT_gnu_precision attribute to the DWARF.

This is exactly the kind of DWARF extension we want to make: in addition
to being useful for LTO, we get better information for the debugger.
Please make sure that any new DWARF attributes are clearly documented,
without reference to GCC internals; the right documentation for
DW_AT_gnu_precision is not "this is TYPE_PRECISION".

However, first we should check if DW_AT_bit_size is being emitted correctly.

Thanks,

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713