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Re: [PATCH v2 3/5] or1k: Add mrori option, fix option docs


On Wed, Jul 03, 2019 at 05:26:58PM -0500, Segher Boessenkool wrote:
> On Thu, Jul 04, 2019 at 06:49:17AM +0900, Stafford Horne wrote:
> > On Wed, Jul 03, 2019 at 09:49:02AM -0500, Segher Boessenkool wrote:
> > > On Wed, Jul 03, 2019 at 12:33:49PM +0900, Stafford Horne wrote:
> > > > @@ -179,11 +183,11 @@
> > > >    [(set (match_operand:SI 0 "register_operand" "=r,r")
> > > >  	(rotatert:SI (match_operand:SI 1 "register_operand"  "r,r")
> > > >  		  (match_operand:SI 2 "reg_or_u6_operand" "r,n")))]
> > > > -  "TARGET_ROR"
> > > > +  "TARGET_ROR || TARGET_RORI"
> > > >    "@
> > > >     l.ror\t%0, %1, %2
> > > >     l.rori\t%0, %1, %2"
> > > > -  [(set_attr "insn_support" "*,shftimm")])
> > > > +  [(set_attr "insn_support" "ror,rori")])
> > > 
> > > Does this work?  If you use -mno-ror -mrori?  It will then allow generating
> > > a reg for the second operand, and ICE later on, as far as I can see?
> > 
> > It does seem to work.  Why would it produce an internal compiler error?
> > 
> > One thing I have is RegectNegative on mror and mrori, so -mno-ror will not be
> > allowed and cause an error.
> 
> But both options are off by default, and neither is enabled or disabled
> based on the setting of the other.
> 
> > Example: 
> > 
> >     $ cat ./gcc/testsuite/gcc.target/or1k/ror-4.c
> > 
> > 	unsigned int rotate6 (unsigned int a) {
> > 	  return ( a >> 6 ) | ( a << ( 32 - 6 ) );
> > 	}
> 
> That's a fixed distance rotate.  My question is will it work if the
> distance is a variable.  The other direction should work fine, agreed.
> 
> So, does ror-[12].c work with -mrori and no -mror?  The predicates say
> this insn pattern is just fine in that case, but the constraints will
> disagree.

OK, yes I see it now.  Sorry I mis-understood what you meant by second argument.
I will fix.  It's probably going to be easiest to split this to 2 instructions.

-Stafford


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