Re: BCT loop fix

[Jeffrey A Law <law at cygnus dot com>]

  In message <9809151802.AA43894@marc.watson.ibm.com>you write:
  > 	I have not heard anything back about the patch that I sent to
  > egcs-patches which I want to install in loop.c to fix the worst Haifa
  > count register bug.
Can you tell we're nearing Cygnus EOQ :-)  Pile prep work for a trip
to Japan on top and I'm totally buried.

It would be appreciated if other maintainers could fill in wherever
possible.


  > 	There still is another bug which I am having more trouble tracking
  > down -- partially because I do not have a lot of time to explore the
  > problem.  When the decrement_and_branch_on_count pattern is substituted,
  > some information about the lifetime of certain condition registers seems
  > to be lost or merged.
  > 
  > 	recog.c:reg_fits_class_p(), when compiled with the BCT
  > optimization, returns a truthvalue obtained from a condition register that
  > has not been set on the particular flow of control.  The truthvalue seems
  > to be calculated; but, in the original code without the BCT instruction,
  > the value was copied to another condition register and the return value
  > obtained from there.  With the BCT instruction, the copy does not occur,
  > but the value still is expected in an alternate condition register.
I haven't looked at the backend stuff related to BCT.  Presumably the
BCT insn shows uses/sets of the CC registers like the other conditional
branches?  That's the only thing I can think of immediately.



jeff