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Nested libcalls (was: Re: RFC: SMS problem with emit_copy_of_insn_after copying REG_NOTEs)


On Sunday 31 December 2006 00:59, Jan Hubicka wrote:
> > Also I should mention, this also fixes a possible bug with libcalls that
> > are embedded in one another.  Before we were just assuming if we have a
> > REG_RETVAL, then the previous REG_LIBCALL would be the start of the
> > libcall but that would be incorrect with embedded libcalls.
>
> We should not have nested libcalls at all.  One level of libcalls is
> painful enough and we take care to not do this.

It's unclear whether we can have nested libcalls or not.  We expect them
in some places (especially, see libcall_stack in gcse.c:local_cprop_pass)
but are bound to fail miserably in others.

This is something I've been wondering for a while.  Maybe someone can
give a definitive answer: Can libcalls be nested, or not?

Gr.
Steven


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