The reason the flags were uninitialized was because they were unused,
similarly for m_type. But you're right, it is icky and prone to bugs.
I just thought it was cheap to set_undefined by just flipping
m_kind=VR_UNDEFINED, but it smells like premature optimization.
How about this?
Aldy
On Wed, Sep 21, 2022 at 9:39 AM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Tue, Sep 20, 2022 at 8:23 PM Aldy Hernandez via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > Undefined ranges have undefined NAN bits. We can't depend on them,
> > as they may contain garbage.
>
> Ick ;) Can you add a comment at least?
>
> > This patch returns false from
> > maybe_isnan() for undefined ranges (the empty set).
> >
> > gcc/ChangeLog:
> >
> > * value-range.h (frange::maybe_isnan): Return false for
> > undefined ranges.
> > ---
> > gcc/value-range.h | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/gcc/value-range.h b/gcc/value-range.h
> > index 7d5584a9294..325ed08f290 100644
> > --- a/gcc/value-range.h
> > +++ b/gcc/value-range.h
> > @@ -1210,6 +1210,8 @@ frange::known_isinf () const
> > inline bool
> > frange::maybe_isnan () const
> > {
> > + if (undefined_p ())
> > + return false;
> > return m_pos_nan || m_neg_nan;
> > }
> >
> > --
> > 2.37.1
> >
>
From f96eb8f4386f2cec67dbf20ab3650aa756fe218a Mon Sep 17 00:00:00 2001
From: Aldy Hernandez <al...@redhat.com>
Date: Wed, 21 Sep 2022 09:49:14 +0200
Subject: [PATCH] Clear unused flags in frange for undefined ranges.
gcc/ChangeLog:
* value-range.cc (frange::combine_zeros): Call set_undefined.
(frange::intersect_nans): Same.
(frange::intersect): Same.
(frange::verify_range): Undefined ranges do not have a type.
* value-range.h (frange::set_undefined): Clear NAN flags and type.
---
gcc/value-range.cc | 8 ++++----
gcc/value-range.h | 4 ++++
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index dc42b6d3120..505eb9211a7 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -422,7 +422,7 @@ frange::combine_zeros (const frange &r, bool union_p)
if (maybe_isnan ())
m_kind = VR_NAN;
else
- m_kind = VR_UNDEFINED;
+ set_undefined ();
changed = true;
}
return changed;
@@ -506,7 +506,7 @@ frange::intersect_nans (const frange &r)
if (maybe_isnan ())
m_kind = VR_NAN;
else
- m_kind = VR_UNDEFINED;
+ set_undefined ();
if (flag_checking)
verify_range ();
return true;
@@ -558,7 +558,7 @@ frange::intersect (const vrange &v)
if (maybe_isnan ())
m_kind = VR_NAN;
else
- m_kind = VR_UNDEFINED;
+ set_undefined ();
if (flag_checking)
verify_range ();
return true;
@@ -696,7 +696,7 @@ frange::verify_range ()
switch (m_kind)
{
case VR_UNDEFINED:
- // m_type is ignored.
+ gcc_checking_assert (!m_type);
return;
case VR_VARYING:
gcc_checking_assert (m_type);
diff --git a/gcc/value-range.h b/gcc/value-range.h
index 325ed08f290..3668b331187 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -1083,6 +1083,10 @@ inline void
frange::set_undefined ()
{
m_kind = VR_UNDEFINED;
+ m_type = NULL;
+ m_pos_nan = false;
+ m_neg_nan = false;
+ // m_min and m_min are unitialized as they are REAL_VALUE_TYPE ??.
if (flag_checking)
verify_range ();
}
--
2.37.1
