PR37363: PR36090 and PR36182 all over again

[Paolo Bonzini]

Hans-Peter Nilsson wrote:
>> Date: Fri, 5 Sep 2008 14:57:00 +0200
>> From: Hans-Peter Nilsson <hp@axis.com>
> 
>> Maybe as part of a change from target macro to target hook, with
>> LEGITIMATE_CONSTANT_P as a default would fit, even at this
>> stage?
> 
> Sorry, I mean CONSTANT_P, not LEGITIMATE_CONSTANT_P.  Or maybe a
> new macro or hook

What about replacing the problematic uses of gen_rtx_CONST with
"plus_constant (x, 0)"?  plus_constant knows when to make a CONST rtx.

There are just a handful of places where this would be needed: instead
of the check after the wrong comment in cse.c, and everywhere
gen_rtx_CONST is used in simplify-rtx.c.

Paolo