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Re: darwin LTO broken under Xcode 3.2.6/4.0
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Jack Howarth <howarth at bromo dot med dot uc dot edu>
- Cc: gcc at gcc dot gnu dot org
- Date: Sun, 13 Mar 2011 12:39:26 +0100
- Subject: Re: darwin LTO broken under Xcode 3.2.6/4.0
- References: <20110313041719.GA17752@bromo.med.uc.edu>
> With release of Xcode 3.2.6/4.0 this week, an unfortunate change was made to
> the darwin assembler which effectively breaks LTO support for darwin. The design
> of LTO on darwin was based on the fact that mach-o object files tolerated additional
> sections as long as they didin't contain symbols. With Xcode 3.2.6/4.0, the assembler
> appears to be strictly counting sections and objecting when these exceed 255. This
> breaks huge sections of the lto testsuite and prevents larger projects like xplor-nih
> to compile if Xcode 3.2.6/4.0 is installed. I am afraid that unless Apple reverts this
> change, our only recourse would be to resort to an elf object container for the lto
> sections within the mach-o files (introducing an undesired dependency on libelf for
> FSF gcc on darwin). My understanding was that the lto design did not allow the number
> of sections required in the lto files to be reduced.
If the problem is not fixed, we could always pack all the LTO sections into one section containing
our own subsections.
Honza
> Jack