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[COMMITTED] Make frange selftests work on !HONOR_NANS systems.

Message ID 20220901070814.2517831-1-aldyh@redhat.com
State New
Headers show
Series [COMMITTED] Make frange selftests work on !HONOR_NANS systems. | expand

Commit Message

Aldy Hernandez Sept. 1, 2022, 7:08 a.m. UTC 
I'm just shuffling the FP self tests here, with no change to existing
functionality.

If we agree that explicit NANs in the source code with !HONOR_NANS
should behave any differently, I'm happy to address whatever needs
fixing, but for now I'd like to unblock the !HONOR_NANS build systems.

I have added an adaptation of a test Jakub suggested we handle in the PR:

void funk(int cond)
{
  float x;

  if (cond)
    x = __builtin_nan ("");
  else
    x = 1.24;

  bar(x);
}

For !HONOR_NANS, the range for the PHI of x_1 is the union of 1.24 and
NAN which is really 1.24 with a maybe NAN.  This reflects the IL-- the
presence of the actual NAN.  However, VRP will propagate this because
it sees the 1.24 and ignores the possibility of a NAN, per
!HONOR_NANS.  IMO, this is correct.  OTOH, for HONOR_NANS the unknown
NAN property keeps us from propagating the value.

Is there a reason we don't warn for calls to __builtin_nan when
!HONOR_NANS?  That makes no sense to me.

	PR tree-optimization/106785

gcc/ChangeLog:

	* value-range.cc (range_tests_nan): Adjust tests for !HONOR_NANS.
	(range_tests_floats): Same.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/vrp-float-nan-1.c: New test.
---
 .../gcc.dg/tree-ssa/vrp-float-nan-1.c         | 18 +++++++++++++++
 gcc/value-range.cc                            | 23 +++++++++++--------
 2 files changed, 32 insertions(+), 9 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp-float-nan-1.c
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Patch

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp-float-nan-1.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp-float-nan-1.c
new file mode 100644
index 00000000000..126949b2b4c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp-float-nan-1.c
@@ -0,0 +1,18 @@ 
+// { dg-do compile }
+// { dg-options "-O2 -ffinite-math-only -fdump-tree-evrp" }
+
+void bar(float);
+
+void funk(int cond)
+{
+  float x;
+
+  if (cond)
+    x = __builtin_nan ("");
+  else
+    x = 1.24;
+
+  bar(x);
+}
+
+// { dg-final { scan-tree-dump-times "bar \\(1.24" 1 "evrp" } }
diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 473139c6dbd..3c7d4cb84b9 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -3535,13 +3535,16 @@  range_tests_nan ()
   REAL_VALUE_TYPE q, r;
 
   // Equal ranges but with differing NAN bits are not equal.
-  r1 = frange_float ("10", "12");
-  r0 = r1;
-  ASSERT_EQ (r0, r1);
-  r0.set_nan (fp_prop::NO);
-  ASSERT_NE (r0, r1);
-  r0.set_nan (fp_prop::YES);
-  ASSERT_NE (r0, r1);
+  if (HONOR_NANS (float_type_node))
+    {
+      r1 = frange_float ("10", "12");
+      r0 = r1;
+      ASSERT_EQ (r0, r1);
+      r0.set_nan (fp_prop::NO);
+      ASSERT_NE (r0, r1);
+      r0.set_nan (fp_prop::YES);
+      ASSERT_NE (r0, r1);
+    }
 
   // NAN ranges are not equal to each other.
   r0 = frange_nan (float_type_node);
@@ -3624,9 +3627,11 @@  range_tests_floats ()
   if (HONOR_SIGNED_ZEROS (float_type_node))
     range_tests_signed_zeros ();
 
-  // A range of [-INF,+INF] is actually VARYING...
+  // A range of [-INF,+INF] is actually VARYING if no other properties
+  // are set.
   r0 = frange_float ("-Inf", "+Inf");
-  ASSERT_TRUE (r0.varying_p ());
+  if (r0.get_nan ().varying_p ())
+    ASSERT_TRUE (r0.varying_p ());
   // ...unless it has some special property...
   r0.set_nan (fp_prop::NO);
   ASSERT_FALSE (r0.varying_p ());