[PATCH v2 10/13] [gdb/symtab] Don't defer backward refs, inter-cu intra-shard case

[Tom de Vries <tdevries@suse.de>]

In patch "[gdb/symtab] Resolve deferred entries, inter-shard case" we've
solved the generic case of handling deferred entries.

Add an optimization that doesn't defer inter-CU intra-shard dependencies that
are present in the shard's parent map.

Tested on x86_64-linux.
---
 gdb/dwarf2/read.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 3d52e908152..610c751818e 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -4528,6 +4528,12 @@ class cooked_index_storage
     m_index->set_parent_valid (start, end);
   }
 
+  /* Return true if find_parents can be relied upon.  */
+  bool parent_valid (CORE_ADDR addr)
+  {
+    return m_index->parent_valid (addr);
+  }
+
 private:
 
   /* Hash function for a cutu_reader.  */
@@ -4676,6 +4682,12 @@ class cooked_indexer
   {
     m_index_storage->set_parent_valid (start, end);
   }
+
+  /* Return true if find_parents can be relied upon.  */
+  bool parent_valid (CORE_ADDR addr)
+  {
+    return m_index_storage->parent_valid (addr);
+  }
 };
 
 /* Subroutine of dwarf2_build_psymtabs_hard to simplify it.
@@ -16242,7 +16254,22 @@ cooked_indexer::scan_attributes (dwarf2_per_cu_data *scanning_per_cu,
 	      else
 		{
 		  /* Inter-CU case.  */
-		  *maybe_defer = addr;
+		  if (parent_valid (addr))
+		    {
+		      auto tmp = find_parent (addr);
+		      if (tmp == &parent_map::deferred)
+			{
+			  /* Defer because origin is deferred.  */
+			  *maybe_defer = addr;
+			}
+		      else
+			*parent_entry = tmp;
+		    }
+		  else
+		    {
+		      /* Defer because origin is in other shard.  */
+		      *maybe_defer = addr;
+		    }
 		}
 	    }
 
-- 
2.35.3