[gcc r17-2764] [frange] Walk sub-ranges when restoring and printing.

https://gcc.gnu.org/g:30e546b781b87188d6b1eed7db8854473fe253e5

commit r17-2764-g30e546b781b87188d6b1eed7db8854473fe253e5
Author: Aldy Hernandez <[email protected]>
Date:   Tue Jul 28 11:18:07 2026 +0000

    [frange] Walk sub-ranges when restoring and printing.
    
    Teach the two remaining single-interval consumers to walk the whole
    set of sub-ranges: frange_storage::get_frange() and the pretty
    printer.
    
    This is also a non-functional change.
    
    Tested on ppc64le: bootstrap, tests, LAPACK, and verifying that
    assembly doesn't change on a corpus of LAPACK fortran preprocessed
    sources.
    
    gcc/ChangeLog:
    
            * value-range-storage.cc (frange_storage::get_frange): Restore
            every sub-range.
            * value-range-pretty-print.cc (vrange_printer::visit): Print each
            sub-range.

Diff:
---
 gcc/value-range-pretty-print.cc | 20 +++++++++++---------
 gcc/value-range-storage.cc      | 12 +++++++-----
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/gcc/value-range-pretty-print.cc b/gcc/value-range-pretty-print.cc
index c3e62b0d73a1..8b857b1d59a9 100644
--- a/gcc/value-range-pretty-print.cc
+++ b/gcc/value-range-pretty-print.cc
@@ -219,15 +219,17 @@ vrange_printer::visit (const frange &r) const
       print_frange_nan (r);
       return;
     }
-  pp_character (pp, '[');
-  bool has_endpoints = !r.known_isnan ();
-  if (has_endpoints)
-    {
-      print_real_value (type, r.lower_bound ());
-      pp_string (pp, ", ");
-      print_real_value (type, r.upper_bound ());
-    }
-  pp_character (pp, ']');
+  if (r.known_isnan ())
+    pp_string (pp, "[]");
+  else
+    for (unsigned i = 0; i < r.num_pairs (); ++i)
+      {
+	pp_character (pp, '[');
+	print_real_value (type, r.lower_bound (i));
+	pp_string (pp, ", ");
+	print_real_value (type, r.upper_bound (i));
+	pp_character (pp, ']');
+      }
   print_frange_nan (r);
 }
 
diff --git a/gcc/value-range-storage.cc b/gcc/value-range-storage.cc
index 6f8b53814a8d..153a2aecb48f 100644
--- a/gcc/value-range-storage.cc
+++ b/gcc/value-range-storage.cc
@@ -556,11 +556,13 @@ frange_storage::get_frange (frange &r, tree type) const
       return;
     }
 
-  // FIXME: Rewrite for sub-ranges.  This only reconstructs the first pair.
-  // Eventually do it piecewise like irange_storage::get_irange: start
-  // undefined and union each sub-range built through the constructor (so
-  // every piece is re-canonicalized).
-  r = frange (type, m_pairs[0].min, m_pairs[0].max, m_kind);
+  // Rebuild piecewise, like irange_storage::get_irange().
+  r.set_undefined ();
+  for (unsigned i = 0; i < m_num_ranges; ++i)
+    {
+      frange tmp (type, m_pairs[i].min, m_pairs[i].max, m_kind);
+      r.union_ (tmp);
+    }
 
   // The constructor will set the NAN bits for HONOR_NANS, but we must
   // make sure to set the NAN sign if known.