[Bug rtl-optimization/84842] [7/8/9 Regression] ICE in verify_target_availability, at sel-sched.c:1569

[abel at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84842

Andrey Belevantsev <abel at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |abel at gcc dot gnu.org

--- Comment #17 from Andrey Belevantsev <abel at gcc dot gnu.org> ---
Created attachment 45991
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45991&action=edit
tentative patch

This is a rather complex situation.  The assert checks that we have correctly
calculated the availability bit, which tells us that the original destination
insn register is free to use for the code motion.  In our case we have merged
several insns into one expression, and the resulting bit came from the variant
when it was really unavailable; however, during looking for the original insn
in the flow graph, we have been looking for really another variant, thus we
didn't get to the place with the first variant and initially unavailable stuff.

It can be fixed with the rather crude attached patch that somewhat relaxes the
assert.  While doing this, we need to mark the above situation has actually
occurred, but we don't know which of the move_op or find_best_regs we're doing
there -- Alexander, maybe you could come up with something better.