[gcc r13-5630] Ranger cache - always use range_from_dom when updating.

[Andrew Macleod <amacleod@gcc.gnu.org>]

https://gcc.gnu.org/g:881bf8de9b07fb501d61ade8f521f1cc9dbe712e

commit r13-5630-g881bf8de9b07fb501d61ade8f521f1cc9dbe712e
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Tue Jan 10 13:40:56 2023 -0500

    Ranger cache - always use range_from_dom when updating.
    
    When updating an existing range, if we dont query the dom tree, we can
    get the global range instead of a proper range on some incoming edges
    which cause the range to not be refined properly.
    
            PR tree-optimization/108356
            gcc/
            * gimple-range-cache.cc (ranger_cache::range_on_edge): Always
            do a search of the DOM tree for a range.
    
            gcc/testsuite/
            * gcc.dg/pr108356.c: New.

Diff:
---
 gcc/gimple-range-cache.cc       |  2 +-
 gcc/testsuite/gcc.dg/pr108356.c | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index a8202f0e895..20c444bc4f4 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -998,7 +998,7 @@ bool
 ranger_cache::range_on_edge (vrange &r, edge e, tree expr)
 {
   if (gimple_range_ssa_p (expr))
-    return edge_range (r, e, expr, RFD_NONE);
+    return edge_range (r, e, expr, RFD_READ_ONLY);
   return get_tree_range (r, expr, NULL);
 }
 
diff --git a/gcc/testsuite/gcc.dg/pr108356.c b/gcc/testsuite/gcc.dg/pr108356.c
new file mode 100644
index 00000000000..1df6b278e45
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr108356.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+char a;
+static char c = 3;
+char d;
+void foo();
+short(b)(short e, short f) { return e + f; }
+int main() {
+  unsigned g = 0;
+  if (c)
+    ;
+  else
+    foo();
+  for (; g < 2; g = b(g, 2)) {
+    d = g ? 0 : a;
+    if (g)
+      c = 0;
+  }
+}
+
+
+/* { dg-final { scan-tree-dump-not "foo" "optimized" } } */