tree-optimization/115701 - factor out maybe_duplicate_ssa_info_at_copy

The following factors out the code that preserves SSA info of the LHS
of a SSA copy LHS = RHS when LHS is about to be eliminated to RHS.

	PR tree-optimization/115701
	* tree-ssanames.h (maybe_duplicate_ssa_info_at_copy): Declare.
	* tree-ssanames.cc (maybe_duplicate_ssa_info_at_copy): New
	function, split out from ...
	* tree-ssa-copy.cc (fini_copy_prop): ... here.
	* tree-ssa-sccvn.cc (eliminate_dom_walker::eliminate_stmt): ...
	and here.

(cherry picked from commit b5c64b413fd5bc03a1a8ef86d005892071e42cbe)

gcc/tree-ssa-copy.cc

@@ -527,38 +527,10 @@ fini_copy_prop (void)
 	  || copy_of[i].value == var)
 	continue;
 
-      /* In theory the points-to solution of all members of the
+      /* Duplicate points-to and range info appropriately.  */
-         copy chain is their intersection.  For now we do not bother
-	 to compute this but only make sure we do not lose points-to
-	 information completely by setting the points-to solution
-	 of the representative to the first solution we find if
-	 it doesn't have one already.  */
       if (copy_of[i].value != var
 	  && TREE_CODE (copy_of[i].value) == SSA_NAME)
-	{
+	maybe_duplicate_ssa_info_at_copy (var, copy_of[i].value);
-	  basic_block copy_of_bb
-	    = gimple_bb (SSA_NAME_DEF_STMT (copy_of[i].value));
-	  basic_block var_bb = gimple_bb (SSA_NAME_DEF_STMT (var));
-	  if (POINTER_TYPE_P (TREE_TYPE (var))
-	      && SSA_NAME_PTR_INFO (var)
-	      && !SSA_NAME_PTR_INFO (copy_of[i].value))
-	    {
-	      duplicate_ssa_name_ptr_info (copy_of[i].value,
-					   SSA_NAME_PTR_INFO (var));
-	      /* Points-to information is cfg insensitive,
-		 but [E]VRP might record context sensitive alignment
-		 info, non-nullness, etc.  So reset context sensitive
-		 info if the two SSA_NAMEs aren't defined in the same
-		 basic block.  */
-	      if (var_bb != copy_of_bb)
-		reset_flow_sensitive_info (copy_of[i].value);
-	    }
-	  else if (!POINTER_TYPE_P (TREE_TYPE (var))
-		   && SSA_NAME_RANGE_INFO (var)
-		   && !SSA_NAME_RANGE_INFO (copy_of[i].value)
-		   && var_bb == copy_of_bb)
-	    duplicate_ssa_name_range_info (copy_of[i].value, var);
-	}
     }
 
   class copy_folder copy_folder;

gcc/tree-ssa-sccvn.cc

@@ -6871,27 +6871,10 @@ eliminate_dom_walker::eliminate_stmt (basic_block b, gimple_stmt_iterator *gsi)
 
       /* If this now constitutes a copy duplicate points-to
 	 and range info appropriately.  This is especially
-	 important for inserted code.  See tree-ssa-copy.cc
+	 important for inserted code.  */
-	 for similar code.  */
       if (sprime
 	  && TREE_CODE (sprime) == SSA_NAME)
-	{
+	maybe_duplicate_ssa_info_at_copy (lhs, sprime);
-	  basic_block sprime_b = gimple_bb (SSA_NAME_DEF_STMT (sprime));
-	  if (POINTER_TYPE_P (TREE_TYPE (lhs))
-	      && SSA_NAME_PTR_INFO (lhs)
-	      && ! SSA_NAME_PTR_INFO (sprime))
-	    {
-	      duplicate_ssa_name_ptr_info (sprime,
-					   SSA_NAME_PTR_INFO (lhs));
-	      if (b != sprime_b)
-		reset_flow_sensitive_info (sprime);
-	    }
-	  else if (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
-		   && SSA_NAME_RANGE_INFO (lhs)
-		   && ! SSA_NAME_RANGE_INFO (sprime)
-		   && b == sprime_b)
-	    duplicate_ssa_name_range_info (sprime, lhs);
-	}
 
       /* Inhibit the use of an inserted PHI on a loop header when
 	 the address of the memory reference is a simple induction

gcc/tree-ssanames.cc

@@ -757,6 +757,34 @@ duplicate_ssa_name_range_info (tree name, tree src)
     }
 }
 
+/* For a SSA copy DEST = SRC duplicate SSA info present on DEST to SRC
+   to preserve it in case DEST is eliminated to SRC.  */
+
+void
+maybe_duplicate_ssa_info_at_copy (tree dest, tree src)
+{
+  if (POINTER_TYPE_P (TREE_TYPE (dest))
+      && SSA_NAME_PTR_INFO (dest)
+      && ! SSA_NAME_PTR_INFO (src))
+    {
+      duplicate_ssa_name_ptr_info (src, SSA_NAME_PTR_INFO (dest));
+      /* Points-to information is cfg insensitive,
+	 but VRP might record context sensitive alignment
+	 info, non-nullness, etc.  So reset context sensitive
+	 info if the two SSA_NAMEs aren't defined in the same
+	 basic block.  */
+      if (gimple_bb (SSA_NAME_DEF_STMT (src))
+	  != gimple_bb (SSA_NAME_DEF_STMT (dest)))
+	reset_flow_sensitive_info (src);
+    }
+  else if (INTEGRAL_TYPE_P (TREE_TYPE (dest))
+	   && SSA_NAME_RANGE_INFO (dest)
+	   && ! SSA_NAME_RANGE_INFO (src)
+	   && (gimple_bb (SSA_NAME_DEF_STMT (src))
+	       == gimple_bb (SSA_NAME_DEF_STMT (dest))))
+    duplicate_ssa_name_range_info (src, dest);
+}
+
 
 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
    in function FN.  */

gcc/tree-ssanames.h

@@ -79,9 +79,10 @@ extern struct ptr_info_def *get_ptr_info (tree);
 extern void set_ptr_nonnull (tree);
 
 extern tree copy_ssa_name_fn (struct function *, tree, gimple *);
-extern void duplicate_ssa_name_ptr_info (tree, struct ptr_info_def *);
 extern tree duplicate_ssa_name_fn (struct function *, tree, gimple *);
+extern void duplicate_ssa_name_ptr_info (tree, struct ptr_info_def *);
 extern void duplicate_ssa_name_range_info (tree dest, tree src);
+extern void maybe_duplicate_ssa_info_at_copy (tree dest, tree src);
 extern void reset_flow_sensitive_info (tree);
 extern void reset_flow_sensitive_info_in_bb (basic_block);
 extern void release_defs (gimple *);