On Thu, 2020-01-23 at 20:05 +0100, Richard Biener wrote:
> On January 23, 2020 7:22:02 PM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
> wrote:
> > Hi!
> >
> > The following testcase is miscompiled, because the postreload pass
> > changes:
> > -(insn 14 13 23 2 (parallel [
> > - (set (reg:DI 1 dx [94])
> > - (plus:DI (reg:DI 1 dx [95])
> > - (reg:DI 5 di [92])))
> > - (clobber (reg:CC 17 flags))
> > - ]) "pr93402.c":8:30 186 {*adddi_1}
> > - (expr_list:REG_EQUAL (plus:DI (reg:DI 5 di [92])
> > - (const_int 111111111111 [0x19debd01c7]))
> > - (nil)))
> > -(insn 23 14 25 2 (set (reg:SI 0 ax)
> > +(insn 23 13 25 2 (set (reg:SI 0 ax)
> > (const_int 0 [0])) "pr93402.c":10:1 67 {*movsi_internal}
> > (nil))
> > (insn 25 23 26 2 (use (reg:SI 0 ax)) "pr93402.c":10:1 -1
> > (nil))
> > -(insn 26 25 35 2 (use (reg:DI 1 dx)) "pr93402.c":10:1 -1
> > +(insn 26 25 35 2 (use (plus:DI (reg:DI 1 dx [95])
> > + (reg:DI 5 di [92]))) "pr93402.c":10:1 -1
> > (nil))
> > A USE insn is not a normal insn and verify_changes called from
> > apply_change_group is happy about any changes into it.
> > The following patch avoids this optimization if we were to change
> > the USE operand (this routine only changes a reg into (plus reg reg2)).
> >
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk and
> > later for release branches?
>
> Ok. Looks like the same thing Richard fixed for autoinc.
Yup. I suppose we still need the naked clobber/use insns and that
there's more of these problems lurking in the weeks.
jeff
>
