re PR tree-optimization/19578 (function pointer propagation fails for noreturn functions (part 2))

PR tree-optimization/19578
	* tree-flow.h (modified_noreturn_calls): Declare.
	(noreturn_call_p): Declare.
	* tree-flow-inline.h (noreturn_call_p): New function.
	(modify_stmt): Add modified noreturn calls to modified_noreturn_calls.
	* tree-cfg.c (modified_noreturn_calls): New variable.
	(cleanup_control_flow): Use noreturn_call_p.  Split basic blocks
	that contain a mid-block noreturn call.
	* tree-ssa.c (delete_tree_ssa): Clear modified_noreturn_calls.

From-SVN: r94610

gcc/ChangeLog

@@ -1,3 +1,15 @@
+2005-02-02  Richard Sandiford  <rsandifo@redhat.com>
+
+	PR tree-optimization/19578
+	* tree-flow.h (modified_noreturn_calls): Declare.
+	(noreturn_call_p): Declare.
+	* tree-flow-inline.h (noreturn_call_p): New function.
+	(modify_stmt): Add modified noreturn calls to modified_noreturn_calls.
+	* tree-cfg.c (modified_noreturn_calls): New variable.
+	(cleanup_control_flow): Use noreturn_call_p.  Split basic blocks
+	that contain a mid-block noreturn call.
+	* tree-ssa.c (delete_tree_ssa): Clear modified_noreturn_calls.
+
 2005-02-02  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* df.c (df_def_record_1, df_uses_record): Don't use

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2005-02-02  Richard Sandiford  <rsandifo@redhat.com>
+
+	PR tree-optimization/19578
+	* gcc.c-torture/compile/20050202-1.c: New test.
+
 2005-02-02  Joseph S. Myers  <joseph@codesourcery.com>
 
 	PR c/19435

gcc/testsuite/gcc.c-torture/compile/20050202-1.c

@@ -0,0 +1,10 @@
+/* From PR 19578.  */
+extern void foo (void) __attribute__((noreturn));
+
+void
+g (void)
+{
+  void (*f) (void) = foo;
+  f ();
+  f ();
+}

gcc/tree-cfg.c

@@ -2052,6 +2052,14 @@ remove_bb (basic_block bb)
   remove_phi_nodes_and_edges_for_unreachable_block (bb);
 }
 
+/* A list of all the noreturn calls passed to modify_stmt.
+   cleanup_control_flow uses it to detect cases where a mid-block
+   indirect call has been turned into a noreturn call.  When this
+   happens, all the instructions after the call are no longer
+   reachable and must be deleted as dead.  */
+
+VEC(tree) *modified_noreturn_calls;
+
 /* Try to remove superfluous control structures.  */
 
 static bool
@@ -2060,7 +2068,16 @@ cleanup_control_flow (void)
   basic_block bb;
   block_stmt_iterator bsi;
   bool retval = false;
-  tree stmt, call;
+  tree stmt;
+
+  /* Detect cases where a mid-block call is now known not to return.  */
+  while (VEC_length (tree, modified_noreturn_calls))
+    {
+      stmt = VEC_pop (tree, modified_noreturn_calls);
+      bb = bb_for_stmt (stmt);
+      if (bb != NULL && last_stmt (bb) != stmt && noreturn_call_p (stmt))
+	split_block (bb, stmt);
+    }
 
   FOR_EACH_BB (bb)
     {
@@ -2076,10 +2093,7 @@ cleanup_control_flow (void)
 
       /* Check for indirect calls that have been turned into
 	 noreturn calls.  */
-      call = get_call_expr_in (stmt);
-      if (call != 0
-	  && (call_expr_flags (call) & ECF_NORETURN) != 0
-	  && remove_fallthru_edge (bb->succs))
+      if (noreturn_call_p (stmt) && remove_fallthru_edge (bb->succs))
 	{
 	  free_dominance_info (CDI_DOMINATORS);
 	  retval = true;

gcc/tree-flow-inline.h

@@ -131,6 +131,14 @@ get_filename (tree expr)
     return "???";
 }
 
+/* Return true if T is a noreturn call.  */
+static inline bool
+noreturn_call_p (tree t)
+{
+  tree call = get_call_expr_in (t);
+  return call != 0 && (call_expr_flags (call) & ECF_NORETURN) != 0;
+}
+
 /* Mark statement T as modified.  */
 static inline void
 modify_stmt (tree t)
@@ -138,6 +146,8 @@ modify_stmt (tree t)
   stmt_ann_t ann = stmt_ann (t);
   if (ann == NULL)
     ann = create_stmt_ann (t);
+  else if (noreturn_call_p (t))
+    VEC_safe_push (tree, modified_noreturn_calls, t);
   ann->modified = 1;
 }
 

gcc/tree-flow.h

@@ -297,6 +297,8 @@ union tree_ann_d GTY((desc ("ann_type ((tree_ann_t)&%h)")))
   struct stmt_ann_d GTY((tag ("STMT_ANN"))) stmt;
 };
 
+extern GTY(()) VEC(tree) *modified_noreturn_calls;
+
 typedef union tree_ann_d *tree_ann_t;
 typedef struct var_ann_d *var_ann_t;
 typedef struct stmt_ann_d *stmt_ann_t;
@@ -310,6 +312,7 @@ static inline stmt_ann_t get_stmt_ann (tree);
 static inline enum tree_ann_type ann_type (tree_ann_t);
 static inline basic_block bb_for_stmt (tree);
 extern void set_bb_for_stmt (tree, basic_block);
+static inline bool noreturn_call_p (tree);
 static inline void modify_stmt (tree);
 static inline void unmodify_stmt (tree);
 static inline bool stmt_modified_p (tree);

gcc/tree-ssa.c

@@ -766,6 +766,7 @@ delete_tree_ssa (void)
   call_clobbered_vars = NULL;
   BITMAP_XFREE (addressable_vars);
   addressable_vars = NULL;
+  modified_noreturn_calls = NULL;
 }