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Re: [PATCH] Fix DCE REG_LIBCALL note moving from noop move insns (PR rtl-optimization/33644)

On Thu, Oct 18, 2007 at 09:18:33AM -0700, Mark Mitchell wrote:
> Anyhow, I'm not seeing any reason for drastic action here.  It seems to
> me like REG_LIBCALL_ID gives us a path forward, so we want to keep it.
> Meanwhile, we need to fix this bug.  I haven't seen anything so far that
> suggests that fixing the bug requires a major change to the
> representation; it just sounds like a bug.

I think for 4.3 the best thing would be apply Eric's patch, as so far really
nothing uses REG_LIBCALL_ID notes (dce.c really doesn't need them ATM and
does a wrong thing with libcalls, where they inhibit optimization rather
than allowing eliminating whole unneeded libcall sequences) and almost no
pass maintains these notes, then once branched REG_LIBCALL_ID can be
reapplied together with addition of --enable-checking verification code
to make sure it is maintained through all the RTL passes and start using it
in various passes.


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