On 23/09/2019 15:15, Segher Boessenkool wrote:
On Mon, Sep 23, 2019 at 11:56:27AM +0100, Andrew Stubbs wrote:
[(set (match_operand:DI 0 "register_operand" "=Sg,v")
(ashift:DI
(match_operand:DI 1 "gcn_alu_operand" " Sg,v")
(match_operand:SI 2 "gcn_alu_operand" " Sg,v")))
(clobber (match_scratch:BI 3 "=cs,X"))]
Unfortunately, the compiler (almost?) exclusively selects the second
alternative, even when this means moving the values from one register
file to the other, and then back again.
The problem is that the scalar instruction clobbers the CC register,
which results in a "reject++" for that alternative in the LRA dump.
What kind of reject? It prints a reason, too.
0 Non input pseudo reload: reject++
Maybe we should make a macro/hook to never do that for your target, for
those flags registers anyway.
That wouldn't be horrible. I suppose I could look at doing that. Any
suggestions how it should or should not work?
Andrew
