[gcc r13-2334] Make frange selftests work on !HONOR_NANS systems.

[Aldy Hernandez <aldyh@gcc.gnu.org>]

https://gcc.gnu.org/g:bdfe0d1ce0aebdb68b77e2c04a0f45956c56b449

commit r13-2334-gbdfe0d1ce0aebdb68b77e2c04a0f45956c56b449
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Wed Aug 31 14:31:12 2022 +0200

    Make frange selftests work on !HONOR_NANS systems.
    
    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.

Diff:
---
 gcc/testsuite/gcc.dg/tree-ssa/vrp-float-nan-1.c | 18 ++++++++++++++++++
 gcc/value-range.cc                              | 23 ++++++++++++++---------
 2 files changed, 32 insertions(+), 9 deletions(-)

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 ());