1 files changed, 38 insertions, 0 deletions
diff --git a/gcc/gimple.c b/gcc/gimple.c
index a75604f..26c78c8 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -4380,4 +4380,42 @@ dump_decl_set (FILE *file, bitmap set)
     fprintf (file, "NIL");
 }
 
+/* Given SSA_NAMEs NAME1 and NAME2, return true if they are candidates for
+   coalescing together, false otherwise.
+
+   This must stay consistent with var_map_base_init in tree-ssa-live.c.  */
+
+bool
+gimple_can_coalesce_p (tree name1, tree name2)
+{
+  /* First check the SSA_NAME's associated DECL.  We only want to
+     coalesce if they have the same DECL or both have no associated DECL.  */
+  tree var1 = SSA_NAME_VAR (name1);
+  tree var2 = SSA_NAME_VAR (name2);
+  var1 = (var1 && (!VAR_P (var1) || !DECL_IGNORED_P (var1))) ? var1 : NULL_TREE;
+  var2 = (var2 && (!VAR_P (var2) || !DECL_IGNORED_P (var2))) ? var2 : NULL_TREE;
+  if (var1 != var2)
+    return false;
+
+  /* Now check the types.  If the types are the same, then we should
+     try to coalesce V1 and V2.  */
+  tree t1 = TREE_TYPE (name1);
+  tree t2 = TREE_TYPE (name2);
+  if (t1 == t2)
+    return true;
+
+  /* If the types are not the same, check for a canonical type match.  This
+     (for example) allows coalescing when the types are fundamentally the
+     same, but just have different names. 
+
+     Note pointer types with different address spaces may have the same
+     canonical type.  Those are rejected for coalescing by the
+     types_compatible_p check.  */
+  if (TYPE_CANONICAL (t1)
+      && TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2)
+      && types_compatible_p (t1, t2))
+    return true;
+
+  return false;
+}
 #include "gt-gimple.h"