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Re: AIX regression due to DFA scheduler merge
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: law at redhat dot com, gcc-patches at gcc dot gnu dot org, Mark Mitchell <mark at codesourcery dot com>
- Date: Fri, 31 May 2002 15:38:56 -0400
- Subject: Re: AIX regression due to DFA scheduler merge
>>>>> Vladimir Makarov writes:
Vlad> For LIBCALL1 function no_conflict_p still returns TRUE. Actually I
Vlad> don't know what solution to choose. The both of them have advantages
Vlad> and disadvantages:
Vlad> Fix in n_conflict_p is easier and permits insn scheduling of two
Vlad> libcalls which, with my point of view, is more important than
Vlad> opportunity in register allocation for processors needing good insn
Vlad> scheduling.
Vlad> On the other hand, we have unclear rtx code (nested libcalls and no
Vlad> dependencies in rtx). Checking the nested calls probably is more
Vlad> expensive. The fix in the scheduler is better with this point of view.
If I understand Jeff's earlier comment correctly, the local-alloc
problem may help with the latent bugs uncovered in the proposed
SCHED_GROUP fix. The SCHED_GROUP patch is necessary for other reasons, so
we may need *both* fixes.
David