[gcc(refs/users/aldyh/heads/ranger-relational)] Suck non-null bit from any immediate dominators.

[gcc(refs/users/aldyh/heads/ranger-relational)] Suck non-null bit from any immediate dominators.

[Aldy Hernandez]

https://gcc.gnu.org/g:6a00894cde564fd2c2b513f9a9dea7d12adac05f

commit 6a00894cde564fd2c2b513f9a9dea7d12adac05f
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Thu Apr 22 17:14:46 2021 +0200

    Suck non-null bit from any immediate dominators.

Diff:
---
 gcc/gimple-range-cache.cc | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index dbe1018b9db..807c65e2956 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -60,7 +60,17 @@ non_null_ref::non_null_deref_p (tree name, basic_block bb)
   if (!m_nn[v])
     process_name (name);
 
-  return bitmap_bit_p (m_nn[v], bb->index);
+  if (bitmap_bit_p (m_nn[v], bb->index))
+    return true;
+
+  // See if any dominator has set non-zero.
+  if (dom_info_available_p (CDI_DOMINATORS))
+    {
+      for ( ; bb; bb = get_immediate_dominator (CDI_DOMINATORS, bb))
+	if (bitmap_bit_p (m_nn[v], bb->index))
+	  return true;
+    }
+  return false;
 }
 
 // Allocate an populate the bitmap for NAME.  An ON bit for a block