Re: [RFC] Curious REG_EQUAL note for multiplication

[Kaz Kojima <kkojima at rr dot iij4u dot or dot jp>]

Michael Matz <matz@suse.de> wrote:
>Yeah, too much I think.  The usage of ashl is just an artifact of how the 
>multiplication by a constant is carried out.  It could also be something 
>else, substraction or the like.  The note is attached to the last insn of 
>the whole sequence (as only then the full target contains the value that 
>the note claims), so that is also were a potential new place for that note 
>would need to be emitted.  And you don't want to have (set x x) insns all 
>over just because something emitted a ashldi3.

I see.  It seems to be a cure worse than the disease.  So my
patch in http://gcc.gnu.org/ml/gcc-patches/2009-05/msg01036.html
might be the only one workaround I can imagine ATM. 

Regards,
	kaz