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Re: strange use of function_invariant_p

On 06/18/2010 08:38 AM, Joern Rennecke wrote:

> You are not only rejecting invalid pic constants, you reject everything
> that's not CONST_INT.  That could also include a
> (const (unspec ...)) for some integer the target has to calculate after
> register allocation / frame layout.

Examples?  I've never seen code that tries to offset the frame pointer
by anything but a const_int.

> I've stumbled over this piece of code in reload1.c:elimination_effects:
>  30134       crux       else if (reg_renumber[regno] < 0 &&
> reg_equiv_constant
>  30134       crux              && reg_equiv_constant[regno]
>  47226        rth              && ! function_invariant_p
> (reg_equiv_constant[regno]))
>  30134       crux       elimination_effects (reg_equiv_constant[regno],
> mem_mode);
>  30134       crux       return;
> When will this condition ever trigger?  If this is not dead code, then
> at least it is lacking a comment.

I can't seem to find anything in the mailing list archives corresponding
to revision 47226.  The testcase is gcc.dg/20011119-1.c.  I agree the
code looks odd.


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