[committed] frange: Fix up foperator_{,not_}equal::fold_range for signed zeros [PR108540]
Commit Message
Hi!
The following testcases are miscompiled, because threader sees some
SSA_NAME would have -0.0 value and when computing range of SSA_NAME == 0.0
foperator_equal::fold_range sees one operand has [-0.0, -0.0] singleton
range, the other [0.0, 0.0], they aren't equal (frange operator== uses
real_identical etc. rather than real comparisons) and so it thinks they
compare unequal. With signed zeros -0.0 == 0.0 is true though, so we
need to special case the both ranges singleton code.
Similarly, if we see op1 range being say [-42.0, -0.0] and op2 range
[0.0, 42.0], we'd check that the intersection of the two ranges is empty
(that is correct) and fold the result of == between such operands to
[0, 0] which is wrong, because -0.0 == 0.0, it needs to be [0, 1].
Similarly for foperator_not_equal::fold_range.
Bootstrapped/regtested on x86_64-linux and i686-linux, approved in the
PR by Aldy, committed to trunk.
2023-01-26 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/108540
* range-op-float.cc (foperator_equal::fold_range): If both op1 and op2
are singletons, use range_true even if op1 != op2
when one range is [-0.0, -0.0] and another [0.0, 0.0]. Similarly,
even if intersection of the ranges is empty and one has
zero low bound and another zero high bound, use range_true_and_false
rather than range_false.
(foperator_not_equal::fold_range): If both op1 and op2
are singletons, use range_false even if op1 != op2
when one range is [-0.0, -0.0] and another [0.0, 0.0]. Similarly,
even if intersection of the ranges is empty and one has
zero low bound and another zero high bound, use range_true_and_false
rather than range_true.
* gcc.c-torture/execute/ieee/pr108540-1.c: New test.
* gcc.c-torture/execute/ieee/pr108540-2.c: New test.
Jakub
Comments
On Thu, 26 Jan 2023, Jakub Jelinek via Gcc-patches wrote:
> committed to trunk.
Picking a random commit: Should we consistently start using "pushed"
instead of "committed"?
In CVS and SVN those two were the same. With GIT it's really a push (to
trunk) we are interested in, not a commit to a local clone, isn't it?
Gerald (who just updated his scripts this week :-)
@@ -607,6 +607,10 @@ foperator_equal::fold_range (irange &r,
{
if (op1 == op2)
r = range_true (type);
+ // If one operand is -0.0 and other 0.0, they are still equal.
+ else if (real_iszero (&op1.lower_bound ())
+ && real_iszero (&op2.lower_bound ()))
+ r = range_true (type);
else
r = range_false (type);
}
@@ -617,7 +621,18 @@ foperator_equal::fold_range (irange &r,
frange tmp = op1;
tmp.intersect (op2);
if (tmp.undefined_p ())
- r = range_false (type);
+ {
+ // If one range is [whatever, -0.0] and another
+ // [0.0, whatever2], we don't know anything either,
+ // because -0.0 == 0.0.
+ if ((real_iszero (&op1.upper_bound ())
+ && real_iszero (&op2.lower_bound ()))
+ || (real_iszero (&op1.lower_bound ())
+ && real_iszero (&op2.upper_bound ())))
+ r = range_true_and_false (type);
+ else
+ r = range_false (type);
+ }
else
r = range_true_and_false (type);
}
@@ -708,10 +723,14 @@ foperator_not_equal::fold_range (irange
// consist of a single value, and then compare them.
else if (op1.singleton_p () && op2.singleton_p ())
{
- if (op1 != op2)
- r = range_true (type);
- else
+ if (op1 == op2)
r = range_false (type);
+ // If one operand is -0.0 and other 0.0, they are still equal.
+ else if (real_iszero (&op1.lower_bound ())
+ && real_iszero (&op2.lower_bound ()))
+ r = range_false (type);
+ else
+ r = range_true (type);
}
else if (!maybe_isnan (op1, op2))
{
@@ -720,7 +739,18 @@ foperator_not_equal::fold_range (irange
frange tmp = op1;
tmp.intersect (op2);
if (tmp.undefined_p ())
- r = range_true (type);
+ {
+ // If one range is [whatever, -0.0] and another
+ // [0.0, whatever2], we don't know anything either,
+ // because -0.0 == 0.0.
+ if ((real_iszero (&op1.upper_bound ())
+ && real_iszero (&op2.lower_bound ()))
+ || (real_iszero (&op1.lower_bound ())
+ && real_iszero (&op2.upper_bound ())))
+ r = range_true_and_false (type);
+ else
+ r = range_true (type);
+ }
else
r = range_true_and_false (type);
}
@@ -0,0 +1,84 @@
+/* PR tree-optimization/108540 */
+
+__attribute__((noipa)) void
+bar (const char *cp, unsigned long size, char sign, int dsgn)
+{
+ if (__builtin_strcmp (cp, "ZERO") != 0 || size != 4 || sign != '-' || dsgn != 1)
+ __builtin_abort ();
+}
+
+__attribute__((noipa)) void
+foo (int x, int ch, double d)
+{
+ const char *cp = "";
+ unsigned long size = 0;
+ char sign = '\0';
+ switch (x)
+ {
+ case 42:
+ if (__builtin_isinf (d))
+ {
+ if (d < 0)
+ sign = '-';
+ cp = "Inf";
+ size = 3;
+ break;
+ }
+ if (__builtin_isnan (d))
+ {
+ cp = "NaN";
+ size = 3;
+ break;
+ }
+ if (d < 0)
+ {
+ d = -d;
+ sign = '-';
+ }
+ else if (d == 0.0 && __builtin_signbit (d))
+ sign = '-';
+ else
+ sign = '\0';
+ if (ch == 'a' || ch == 'A')
+ {
+ union U { long long l; double d; } u;
+ int dsgn;
+ u.d = d;
+ if (u.l < 0)
+ {
+ dsgn = 1;
+ u.l &= 0x7fffffffffffffffLL;
+ }
+ else
+ dsgn = 0;
+ if (__builtin_isinf (d))
+ {
+ cp = "INF";
+ size = 3;
+ }
+ else if (__builtin_isnan (d))
+ {
+ cp = "NAN";
+ size = 3;
+ }
+ else if (d == 0)
+ {
+ cp = "ZERO";
+ size = 4;
+ }
+ else
+ {
+ cp = "WRONG";
+ size = 5;
+ }
+ bar (cp, size, sign, dsgn);
+ }
+ }
+}
+
+int
+main ()
+{
+ foo (42, 'a', -0.0);
+ return 0;
+}
@@ -0,0 +1,23 @@
+/* PR tree-optimization/108540 */
+
+__attribute__((noipa)) int
+foo (int x, double d)
+{
+ if (x == 42)
+ d = -0.0;
+ if (d == 0.0)
+ return 42;
+ return 12;
+}
+
+int
+main ()
+{
+ if (foo (42, 5.0) != 42
+ || foo (42, 0.0) != 42
+ || foo (42, -0.0) != 42
+ || foo (10, 5.0) != 12
+ || foo (10, 0.0) != 42
+ || foo (10, -0.0) != 42)
+ __builtin_abort ();
+}