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

[Aldy Hernandez <aldyh@redhat.com>]

[Richi/Jakub/FP experts, does this sound like the right solution, or am I
missing some subtle IPA/inlining issue?]

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.
---
 gcc/testsuite/gcc.dg/tree-ssa/pr107394.c | 22 ++++++++++++++++++++++
 gcc/value-range-storage.cc               | 18 +++++++-----------
 2 files changed, 29 insertions(+), 11 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr107394.c

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..b660102e064 100644
--- a/gcc/value-range-storage.cc
+++ b/gcc/value-range-storage.cc
@@ -261,17 +261,13 @@ 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 ();
+  // 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
-- 
2.37.3