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Re: dragonegg in FSF gcc?
On 12/04/2010 17:03, Steven Bosscher wrote:
> On Mon, Apr 12, 2010 at 5:59 PM, Jack Howarth wrote:
>
>> I have opened PR43729, "MachO LTO support needed for darwin", to discuss
>> this. Can you point me at Dave's previous patches that added LTO-suppport
>> to a non-ELF platform?
>
> I've linked your new PR to the existing "LTO doesn't work on non-ELF
> platform" PR. We even discussed Mach-O already there.
>
>> Also, I was unaware that this feat had been performed
>> on a target which both is non-ELF and non-binutils.
>
> AFAIK cygwin also uses binutils, but no changes are needed to make LTO
> work with the collect2 approach (Dave is that correct?).
Binutils for COFF targets needed a patch to allow sections to be
byte-aligned and byte-packed, as it wasn't originally possible to use any
alignment directive to reduce the section alignment below the default, and the
zip-compressed data sections need to be exactly sized to the data they contain
rather than padded up to the default section alignment of 4.
If MachO can do that already, it won't need any changes. Or it could be
fixed in GCC by modifying the format of the compressed sections to be
self-describing w.r.t valid data length in some way - this would probably be
the better thing to do in the long run.
cheers,
DaveK