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Re: LTO and adding extra information from extra passes
On Wed, Sep 2, 2009 at 10:24 PM, Basile
STARYNKEVITCH<basile@starynkevitch.net> wrote:
> Richard Guenther wrote:
>>
>> On Wed, Sep 2, 2009 at 10:06 PM, Basile
>> STARYNKEVITCH<basile@starynkevitch.net> wrote:
>>>
>>> Hello All,
>>>
>>> My feeling is that the Link Time Optimisation (LTO) effort should be soon
>>> (=is expected to be, or is already) merged inside GCC trunk (future 4.5).
>>>
>>> Several years ago, I asked if there is any possibility for an additional
>>> pass to profit of LTO infrastructure to add some extra data into LTO
>>> stuff
>>> (which is probably DWARF related inside ELF object files, but I am not
>>> sure)
>>> and to retrieve it. I remember that the answer was of course not.
>
> [...]
>
>>>
>>> I could imagine that a plugin might be interested in adding say some
>>> information into the object file (when ordinary compilation for LTO of a
>>> single compilation unit happens) and later retrieve it (when link time
>>> optimisation occur merging several object files.)
>>>
>>> A dream case example would be a plugin for whole program static analysis.
>>
>> The IPA pass infrastructure has all the necessary bits for this.
>
> How do you deal with several compilation units?
>
> I was thinking LTO is designed for that?
I of course mean the IPA pass infrastructure on the LTO branch.
Richard.