http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57131
Vladimir Makarov <vmakarov at redhat dot com> changed:
What |Removed |Added
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CC| |vmakarov at redhat dot com
--- Comment #3 from Vladimir Makarov <vmakarov at redhat dot com> 2013-05-02
03:03:34 UTC ---
(In reply to comment #2)
> Apparently went away with the http://gcc.gnu.org/r198432 fix, but it isn't
> clear whether that change was meant to fix this or just made the bug latent.
> Anyway, still reproduceable on the 4.8 branch.
> What I'm seeing before that change is that extendsidi2_1 pattern with MEM
> destination LRA chooses %ebx as (clobber (scratch:SI)) register, eventhough
> %ebx
> is live across that instruction (there is
> (insn 14 74 68 2 (set (reg:SI 3 bx [orig:83 D.1395 ] [83])
> (mem/v/c:SI (plus:SI (reg/f:SI 7 sp)
> (const_int 72 [0x48])) [0 x4+0 S4 A64])) pr57131.c:11 85
> {*movsi_internal}
> (nil))
> (insn 68 14 73 2 (set (reg:SI 3 bx [orig:83 D.1395 ] [83])
> (reg:SI 3 bx [orig:83 D.1395 ] [83])) pr57131.c:11 85
> {*movsi_internal}
> (expr_list:REG_DEAD (reg:SI 3 bx [orig:83 D.1395 ] [83])
> (nil)))
> some insns before it and:
> (insn 65 24 26 2 (set (reg:SI 5 di [orig:83 D.1395 ] [83])
> (reg:SI 3 bx [orig:83 D.1395 ] [83])) pr57131.c:11 85
> {*movsi_internal}
> (expr_list:REG_DEAD (reg:SI 3 bx [orig:83 D.1395 ] [83])
> (nil)))
> some insns after it. Not sure if the noop move with REG_DEAD has anything to
> do with that. Vlad, can you please have a look?
http://gcc.gnu.org/r198432 was a right solution for this bug. LRA don't pay
attention to NO_REGS pseudos during assignment although ebx was assigned to
NO_REGS r95 (which is reflected in reg_renumber).
At some points of LRA work reg notes can be invalid. LRA makes them up to date
after live subpass (lra-lives.c). It needs only correct live info on bb
borders.
So I'd close this PR.
