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Re: Problems building GNAT on OS X with top-of-tree


On Thursday, October 17, 2002, at 02:52  PM, Dale Johannesen wrote:

On Thursday, October 17, 2002, at 02:38  PM, Geoffrey Keating wrote:
On Thursday, October 17, 2002, at 02:10  PM, Dale Johannesen wrote:
Actually this looks like it is connected to Geoff's recent patch
http://gcc.gnu.org/ml/gcc-patches/2002-09/msg01259.html
which introduced the LSJR label.  Geoff, is
current_function_uses_pic_offset_table not getting set anywhere?
That would account for his symptom.

It is supposed to be set by machopic_function_base_name, which is called to generate the label. Looking at the code, my suspicion is that the original load_macho_picbase pattern is getting deleted by flow because it appears dead, but that also deletes the label that the macho_correct_pic needs.

If so, the solution is to use a real CODE_LABEL instead of having the label inside load_macho_picbase, but this will be a complex change.
Hmm. How do you keep the bcl and the following label together through the scheduler?
SCHED_GROUP_P used to work on labels, but it doesn't any more, and I never found
another way to do it. Would a USE of the label work?
That's a tricky one.

What you really want to do is say

(parallel [(set (pc) (label_ref (code_label ...)))
(set (reg:SI lr) (label_ref (code_label ...)))])

because that accurately describes what load_macho_picbase really does, but reload can't deal with that, it doesn't like jump instructions that have output reloads.

Since we can't do the nice thing, probably a good second-best is, for functions that need this restore (perhaps those that have current_function_has_nonlocal_label set) to ensure that the original load_macho_picbase never gets deleted by adding a suitable USE of the PIC register.


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