[gcc r13-3525] [PR tree-optimization/107394] Canonicalize global franges as they are read back.

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

https://gcc.gnu.org/g:2b1fb720818a85d5c893ce65d140add40debf2ff

commit r13-3525-g2b1fb720818a85d5c893ce65d140add40debf2ff
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Tue Oct 25 22:44:51 2022 +0200

    [PR tree-optimization/107394] Canonicalize global franges as they are read back.
    
    The problem here is that we're inlining a global range with NANs into
    a function that has been tagged with __attribute__((optimize
    ("-ffinite-math-only"))).  As the global range is copied from
    SSA_NAME_RANGE_INFO, its NAN bits are copied, which then cause
    frange::verify_range() to fail a sanity check making sure no NANs
    creep in when !HONOR_NANS.
    
    I think what we should do is nuke the NAN bits as we're restoring the
    global range.  For that matter, if we use the frange constructor,
    everything except that NAN sign will be done automatically, including
    dropping INFs to the min/max representable range when appropriate.
    
            PR tree-optimization/107394
    
    gcc/ChangeLog:
    
            * value-range-storage.cc (frange_storage_slot::get_frange): Use
            frange constructor.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/tree-ssa/pr107394.c: New test.

Diff:
---
 gcc/testsuite/gcc.dg/tree-ssa/pr107394.c | 22 +++++++++++++++++++++
 gcc/value-range-storage.cc               | 33 +++++++++++++++++++++-----------
 2 files changed, 44 insertions(+), 11 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr107394.c b/gcc/testsuite/gcc.dg/tree-ssa/pr107394.c
new file mode 100644
index 00000000000..0e1e5ac40ce
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr107394.c
@@ -0,0 +1,22 @@
+// { dg-do compile }
+// { dg-options "-O2" }
+
+static double
+quux (double x)
+{
+  return __builtin_fabs (x);
+}
+
+__attribute__ ((flatten, optimize ("-ffinite-math-only"))) static int
+bar (int *p)
+{
+  *p = quux (0.0);
+
+  return 0;
+}
+
+void
+foo (int *p)
+{
+  (void) bar (p);
+}
diff --git a/gcc/value-range-storage.cc b/gcc/value-range-storage.cc
index 6e054622830..462447ba250 100644
--- a/gcc/value-range-storage.cc
+++ b/gcc/value-range-storage.cc
@@ -261,17 +261,28 @@ frange_storage_slot::get_frange (frange &r, tree type) const
 {
   gcc_checking_assert (r.supports_type_p (type));
 
-  r.set_undefined ();
-  r.m_kind = m_kind;
-  r.m_type = type;
-  r.m_min = m_min;
-  r.m_max = m_max;
-  r.m_pos_nan = m_pos_nan;
-  r.m_neg_nan = m_neg_nan;
-  r.normalize_kind ();
-
-  if (flag_checking)
-    r.verify_range ();
+  // Handle explicit NANs.
+  if (m_kind == VR_NAN)
+    {
+      if (HONOR_NANS (type))
+	{
+	  if (m_pos_nan && m_neg_nan)
+	    r.set_nan (type);
+	  else
+	    r.set_nan (type, m_neg_nan);
+	}
+      else
+	r.set_undefined ();
+      return;
+    }
+
+  // Use the constructor because it will canonicalize the range.
+  r = frange (type, m_min, m_max, m_kind);
+
+  // The constructor will set the NAN bits for HONOR_NANS, but we must
+  // make sure to set the NAN sign if known.
+  if (HONOR_NANS (type) && (m_pos_nan ^ m_neg_nan) == 1)
+    r.update_nan (m_neg_nan);
 }
 
 bool