On Wed, Sep 08, 2021 at 05:23:40PM +0800, Hongtao Liu wrote:
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> >
> Patch LGTM.
Thanks, committed.
> PS:
> I'm curious why we need the post_reload splitter @xorsign<mode>3_1
> for scalar mode, can't we just expand them into and/xor operations in
> the expander, just like vector modes did.
> Let me do some experiments to see whether it is ok to remove the splitter.
I bet it is the question how should the code look like before RA.
stv is somewhat related, but as that replaces whole chains, it can do:
(insn 14 5 6 2 (set (subreg:V2DI (reg:DI 92) 0)
(vec_concat:V2DI (mem/c:DI (symbol_ref:SI ("c") [flags 0x2] <var_decl
0x7f65a131fd80 c>) [1 c+0 S8 A64])
(const_int 0 [0]))) "hohohou.c":6:9 -1
(nil))
on loads of memory.
But it stv still does use paradoxical subregs:
(insn 10 16 11 2 (set (subreg:V2DI (reg:DI 91) 0)
(minus:V2DI (subreg:V2DI (reg:DI 87) 0)
(subreg:V2DI (reg:DI 94) 0))) "hohohou.c":6:13 5003 {*subv2di3}
(expr_list:REG_DEAD (reg:DI 87)
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil))))
(insn 11 10 0 2 (set (mem/c:DI (symbol_ref:SI ("a") [flags 0x2] <var_decl
0x7f65a131fc60 a>) [1 a+0 S8 A64])
(reg:DI 91)) "hohohou.c":6:5 76 {*movdi_internal}
(expr_list:REG_DEAD (reg:DI 91)
(nil)))
so perhaps just using paradoxical subregs everywhere would be ok?
Jakub
