On Tue, Sep 6, 2022 at 9:59 AM Jakub Jelinek <ja...@redhat.com> wrote:
>
> On Tue, Sep 06, 2022 at 09:49:55AM +0200, Aldy Hernandez wrote:
> > On Tue, Sep 6, 2022 at 9:44 AM Jakub Jelinek <ja...@redhat.com> wrote:
> > >
> > > On Tue, Sep 06, 2022 at 09:40:59AM +0200, Aldy Hernandez wrote:
> > > > if (x <= Inf)
> > >
> > > This will be [-Inf, Inf] !NAN on the true side and
> > > NAN (either sign) on the false side indeed.
> > >
> > > > if (x < -Inf)
> > >
> > > will be NAN (either sign) on the true side and
> > > [-Inf, Inf] !NAN on the false side.
> >
> > Sweet, that's exactly what I thought, thus the patch.
> >
> > Furthermore, for !HONOR_NANS I would expect the NAN sides above to be
> > UNDEFINED/unreachable. That is, the false side of x <= Inf when
> > !HONOR_NANS is unreachable.
>
> In practice, there is no real format that has NaNs and doesn't have Infs
> or vice versa and similarly we have just one switch to cover both Infinities
> and NaNs, so either both are supported, or neither of them, or both
> are supported but neither of them should appear in a valid program
> (-ffinite-math-only on most floating point formats).
> So the answer in that case is a little bit fuzzy because one shouldn't
> compare against infinity in that case (or for !MODE_HAS_INFINITIES even
> can't). But sure, if NaNs aren't possible or can't appear and you compare
> x <= Largest_possible_float, then it is always true and so UNDEFINED on the
> false edge.
OK, let's leave it as undefined to be consistent.
Come to think of it, perhaps we could represent the endpoints
(varying, [x, +INF], etc) as the min/max representable values for the
type (for !HONOR_NANS). I don't think it would make a big difference,
but we might get better results for some corner cases.
Question...for !HONOR_NANS or !HONOR_INFINITIES or whatever, say the
range for the domain is [-MIN, +MAX] for the min and max representable
numbers. What happens for MAX+1? Is that undefined? I wonder what
real.cc does for that.
Attached is the final version of the patch I'm pushing. Tested (+mpfr
tests) on x86-64 Linux.
Aldy
From fd52ffb9997becafa31c5109b50fe274da12aed8 Mon Sep 17 00:00:00 2001
From: Aldy Hernandez <al...@redhat.com>
Date: Tue, 6 Sep 2022 08:20:54 +0200
Subject: [PATCH] Handle > INF and < INF correctly in range-op-float.cc
The gfortran.dg/minlocval*.f90 tests are generating conditionals past
the infinities. For example:
if (x <= +Inf)
foo (x);
else
bar (x);
It seems to me that the only possible value for x on the false side is
either NAN or undefined (for !HONOR_NANS).
gcc/ChangeLog:
* range-op-float.cc (build_le): Handle NANs and going past infinity.
(build_lt): Same.
(build_ge): Same.
(build_gt): Same.
(foperator_lt::op1_range): Avoid adjustments to range if build_*
returned false.
(foperator_lt::op2_range): Same.
(foperator_le::op1_range): Same.
(foperator_le::op2_range): Same.
(foperator_gt::op1_range): Same.
(foperator_gt::op2_range): Same.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/vrp-float-inf-1.c: New test.
---
gcc/range-op-float.cc | 99 ++++++++++++++-----
.../gcc.dg/tree-ssa/vrp-float-inf-1.c | 15 +++
2 files changed, 90 insertions(+), 24 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp-float-inf-1.c
diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
index 050f07a9867..5fbbaa1fb36 100644
--- a/gcc/range-op-float.cc
+++ b/gcc/range-op-float.cc
@@ -224,36 +224,79 @@ frange_drop_ninf (frange &r, tree type)
// (X <= VAL) produces the range of [-INF, VAL].
-static void
+static bool
build_le (frange &r, tree type, const REAL_VALUE_TYPE &val)
{
+ if (real_isnan (&val))
+ {
+ r.set_undefined ();
+ return false;
+ }
r.set (type, dconstninf, val);
+ return true;
}
// (X < VAL) produces the range of [-INF, VAL).
-static void
+static bool
build_lt (frange &r, tree type, const REAL_VALUE_TYPE &val)
{
+ if (real_isnan (&val))
+ {
+ r.set_undefined ();
+ return false;
+ }
+ // < -INF is outside the range.
+ if (real_isinf (&val, 1))
+ {
+ if (HONOR_NANS (type))
+ frange_set_nan (r, type);
+ else
+ r.set_undefined ();
+ return false;
+ }
// Hijack LE because we only support closed intervals.
build_le (r, type, val);
+ return true;
}
// (X >= VAL) produces the range of [VAL, +INF].
-static void
+static bool
build_ge (frange &r, tree type, const REAL_VALUE_TYPE &val)
{
+ if (real_isnan (&val))
+ {
+ r.set_undefined ();
+ return false;
+ }
r.set (type, val, dconstinf);
+ return true;
}
// (X > VAL) produces the range of (VAL, +INF].
-static void
+static bool
build_gt (frange &r, tree type, const REAL_VALUE_TYPE &val)
{
+ if (real_isnan (&val))
+ {
+ r.set_undefined ();
+ return false;
+ }
+ // > +INF is outside the range.
+ if (real_isinf (&val, 0))
+ {
+ if (HONOR_NANS (type))
+ frange_set_nan (r, type);
+ else
+ r.set_undefined ();
+ return false;
+ }
+
// Hijack GE because we only support closed intervals.
build_ge (r, type, val);
+ return true;
}
@@ -520,10 +563,12 @@ foperator_lt::op1_range (frange &r,
switch (get_bool_state (r, lhs, type))
{
case BRS_TRUE:
- build_lt (r, type, op2.upper_bound ());
- r.set_nan (fp_prop::NO);
- // x < y implies x is not +INF.
- frange_drop_inf (r, type);
+ if (build_lt (r, type, op2.upper_bound ()))
+ {
+ r.set_nan (fp_prop::NO);
+ // x < y implies x is not +INF.
+ frange_drop_inf (r, type);
+ }
break;
case BRS_FALSE:
@@ -546,10 +591,12 @@ foperator_lt::op2_range (frange &r,
switch (get_bool_state (r, lhs, type))
{
case BRS_TRUE:
- build_gt (r, type, op1.lower_bound ());
- r.set_nan (fp_prop::NO);
- // x < y implies y is not -INF.
- frange_drop_ninf (r, type);
+ if (build_gt (r, type, op1.lower_bound ()))
+ {
+ r.set_nan (fp_prop::NO);
+ // x < y implies y is not -INF.
+ frange_drop_ninf (r, type);
+ }
break;
case BRS_FALSE:
@@ -618,8 +665,8 @@ foperator_le::op1_range (frange &r,
switch (get_bool_state (r, lhs, type))
{
case BRS_TRUE:
- build_le (r, type, op2.upper_bound ());
- r.set_nan (fp_prop::NO);
+ if (build_le (r, type, op2.upper_bound ()))
+ r.set_nan (fp_prop::NO);
break;
case BRS_FALSE:
@@ -642,8 +689,8 @@ foperator_le::op2_range (frange &r,
switch (get_bool_state (r, lhs, type))
{
case BRS_TRUE:
- build_ge (r, type, op1.lower_bound ());
- r.set_nan (fp_prop::NO);
+ if (build_ge (r, type, op1.lower_bound ()))
+ r.set_nan (fp_prop::NO);
break;
case BRS_FALSE:
@@ -712,10 +759,12 @@ foperator_gt::op1_range (frange &r,
switch (get_bool_state (r, lhs, type))
{
case BRS_TRUE:
- build_gt (r, type, op2.lower_bound ());
- r.set_nan (fp_prop::NO);
- // x > y implies x is not -INF.
- frange_drop_ninf (r, type);
+ if (build_gt (r, type, op2.lower_bound ()))
+ {
+ r.set_nan (fp_prop::NO);
+ // x > y implies x is not -INF.
+ frange_drop_ninf (r, type);
+ }
break;
case BRS_FALSE:
@@ -738,10 +787,12 @@ foperator_gt::op2_range (frange &r,
switch (get_bool_state (r, lhs, type))
{
case BRS_TRUE:
- build_lt (r, type, op1.upper_bound ());
- r.set_nan (fp_prop::NO);
- // x > y implies y is not +INF.
- frange_drop_inf (r, type);
+ if (build_lt (r, type, op1.upper_bound ()))
+ {
+ r.set_nan (fp_prop::NO);
+ // x > y implies y is not +INF.
+ frange_drop_inf (r, type);
+ }
break;
case BRS_FALSE:
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp-float-inf-1.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp-float-inf-1.c
new file mode 100644
index 00000000000..1d21cce41e6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp-float-inf-1.c
@@ -0,0 +1,15 @@
+// { dg-do compile }
+// { dg-options "-O2 -fdump-tree-evrp-details" }
+
+void foo ();
+void bar (double);
+
+void funky(double f, double g)
+{
+ if (f <= __builtin_inf ())
+ foo ();
+ else
+ bar (f);
+}
+
+// { dg-final { scan-tree-dump-not " Inf, Inf" "evrp" } }
--
2.37.1
