Re: HPPA constructor merge patch, PR middle-end/45388

[Richard Henderson <rth at redhat dot com>]

On 09/28/2010 08:36 AM, Jan Hubicka wrote:
> This is bit difficult to arrange with LTO.  We produce at compile time the consturctor
> function with magic names, then at LTO time we want to produce single constructor function
> calling them all.   We would need to guess on what name is the magic name (by same logic
> as what collect does) and rename function back.
> I can definitly implement it, but it seems more hackish than the collect2 side change.

An alternative is that at compile time we emit

  _Z41__static_initialization_and_destruction_0ii

to the intermediate code as the constructor, and

  GLOBAL__I__ZN2c12f6Ev calls

to the object code calling _Z41.  However, we don't emit
GLOBAL to the intermediate code at all.  Thus when LTO 
replaces the object files there's no trace of the original
GLOBAL function at all, and thus collect2 does not see it.
LTO will simply see _Z41 and call that function directly.

This is not entirely different from the case in which we
have .ctor support -- it's not like we read in the piece
of the object code that contains the .ctor data.  Just
consider the GLOBAL function object file data.

This should be doable with a flag on the decl for GLOBAL
that indicates that it should not be serialized.


r~