On Thu, Feb 23, 2017 at 03:07:14PM +0100, Jakub Jelinek wrote:
> On Thu, Feb 23, 2017 at 02:47:11PM +0100, Bernd Schmidt wrote:
> > On 02/23/2017 02:36 PM, Jakub Jelinek wrote:
> > > and both UNLT and GE can be reversed. But if the arguments of the
> > > condition
> > > are canonicalized, we run into:
> > > /* Test for an integer condition, or a floating-point comparison
> > > in which NaNs can be ignored. */
> > > if (CONST_INT_P (arg0)
> > > || (GET_MODE (arg0) != VOIDmode
> > > && GET_MODE_CLASS (mode) != MODE_CC
> > > && !HONOR_NANS (mode)))
> > > return reverse_condition (code);
> > > and thus always return UNKNOWN.
> >
> > So... do you think we could add (in gcc-8, probably, although if it fixes
> > this regression...)
> >
> > else if (GET_MODE (arg0) != VOIDmode
> > && GET_MODE_CLASS (mode) != MODE_CC
> > && HONOR_NANS (mode))
> > return reverse_condition_maybe_unordered (code);
> >
> > to make this work?
>
> Maybe, though I'd feel safer about trying it only in gcc 8. I can certainly
> test such a change on a couple of targets. It would not be sufficient, we'd
> either need to also reverse_condition_maybe_unordered for the UN* codes
> we don't handle yet, or break so that we perhaps reach this spot.
>
> Updated (not yet tested) version of the patch is below.
Now successfully bootstrapped/regtested on x86_64-linux and i686-linux, ok
for trunk?
> 2017-02-23 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/79389
> * ifcvt.c (struct noce_if_info): Add rev_cond field.
> (noce_reversed_cond_code): New function.
> (noce_emit_store_flag): Use rev_cond if non-NULL instead of
> reversed_comparison_code. Formatting fix.
> (noce_try_store_flag): Test rev_cond != NULL in addition to
> reversed_comparison_code.
> (noce_try_store_flag_constants): Likewise.
> (noce_try_store_flag_mask): Likewise.
> (noce_try_addcc): Use rev_cond if non-NULL instead of
> reversed_comparison_code.
> (noce_try_cmove_arith): Likewise. Formatting fixes.
> (noce_try_minmax, noce_try_abs): Clear rev_cond.
> (noce_find_if_block): Initialize rev_cond.
> (find_cond_trap): Call noce_get_condition with then_bb == trap_bb
> instead of false as last argument never attempt to reverse it
> afterwards.
Jakub
