re PR tree-optimization/26804 (Alias Time explosion)

2006-03-25  Daniel Berlin  <dberlin@dberlin.org>

	PR tree-optimization/26804
	* tree.h (DECL_CALL_CLOBBERED): New macro.
	(tree_decl_common): Add call_clobbered_flag.
	* tree-flow-inline.h (is_call_clobbered): Use DECL_CALL_CLOBBERED.
	(mark_call_clobbered): Set DECL_CALL_CLOBBERED.
	(clear_call_clobbered): Clear DECL_CALL_CLOBBERED.
	(mark_non_addressable): Ditto.
	* tree-ssa.c (verify_call_clobbered): New function.
	(verify_alias_info): Use it.
	* tree-pass.h (pass_reset_cc_flags): New prototype.
	* tree-ssa-alias.c (pass_reset_cc_flags): New structure.
	(reset_cc_flags): New function.
	* passes.c (init_optimization_passes): Call reset_cc_flags after
	initializing referenced_vars.

From-SVN: r112380

gcc/ChangeLog

+2006-03-25  Daniel Berlin  <dberlin@dberlin.org>
+
+	PR tree-optimization/26804
+	* tree.h (DECL_CALL_CLOBBERED): New macro.
+	(tree_decl_common): Add call_clobbered_flag.
+	* tree-flow-inline.h (is_call_clobbered): Use DECL_CALL_CLOBBERED.
+	(mark_call_clobbered): Set DECL_CALL_CLOBBERED.
+	(clear_call_clobbered): Clear DECL_CALL_CLOBBERED.
+	(mark_non_addressable): Ditto.
+	* tree-ssa.c (verify_call_clobbered): New function.
+	(verify_alias_info): Use it.
+	* tree-pass.h (pass_reset_cc_flags): New prototype.
+	* tree-ssa-alias.c (pass_reset_cc_flags): New structure.
+	(reset_cc_flags): New function.
+	* passes.c (init_optimization_passes): Call reset_cc_flags after
+	initializing referenced_vars.
+
 2006-03-25  Uros Bizjak  <uros@kss-loka.si>
 	    Roger Sayle  <roger@eyesopen.com>
 

gcc/passes.c

@@ -487,6 +487,7 @@ init_optimization_passes (void)
 
   p = &pass_all_optimizations.sub;
   NEXT_PASS (pass_referenced_vars);
+  NEXT_PASS (pass_reset_cc_flags);
   NEXT_PASS (pass_create_structure_vars);
   NEXT_PASS (pass_build_ssa);
   NEXT_PASS (pass_may_alias);

gcc/tree-flow-inline.h

@@ -821,6 +821,9 @@ loop_containing_stmt (tree stmt)
 static inline bool
 is_call_clobbered (tree var)
 {
+  if (!MTAG_P (var))
+    return DECL_CALL_CLOBBERED (var);
+  else
     return bitmap_bit_p (call_clobbered_vars, DECL_UID (var)); 
 }
 
@@ -829,6 +832,8 @@ static inline void
 mark_call_clobbered (tree var, unsigned int escape_type)
 {
   var_ann (var)->escape_mask |= escape_type;
+  if (!MTAG_P (var))
+    DECL_CALL_CLOBBERED (var) = true;
   bitmap_set_bit (call_clobbered_vars, DECL_UID (var));
 }
 
@@ -840,6 +845,8 @@ clear_call_clobbered (tree var)
   ann->escape_mask = 0;
   if (MTAG_P (var) && TREE_CODE (var) != STRUCT_FIELD_TAG)
     MTAG_GLOBAL (var) = 0;
+  if (!MTAG_P (var))
+    DECL_CALL_CLOBBERED (var) = false;
   bitmap_clear_bit (call_clobbered_vars, DECL_UID (var));
 }
 
@@ -847,6 +854,8 @@ clear_call_clobbered (tree var)
 static inline void
 mark_non_addressable (tree var)
 {
+  if (!MTAG_P (var))
+    DECL_CALL_CLOBBERED (var) = false;
   bitmap_clear_bit (call_clobbered_vars, DECL_UID (var));
   TREE_ADDRESSABLE (var) = 0;
 }

gcc/tree-pass.h

@@ -304,6 +304,7 @@ extern struct tree_opt_pass pass_uncprop;
 extern struct tree_opt_pass pass_return_slot;
 extern struct tree_opt_pass pass_reassoc;
 extern struct tree_opt_pass pass_rebuild_cgraph_edges;
+extern struct tree_opt_pass pass_reset_cc_flags;
 
 /* IPA Passes */
 extern struct tree_opt_pass pass_ipa_cp;

gcc/tree-ssa-alias.c

@@ -3193,3 +3193,34 @@ struct tree_opt_pass pass_create_structure_vars =
   TODO_dump_func,	 /* todo_flags_finish */
   0			 /* letter */
 };
+
+/* Reset the DECL_CALL_CLOBBERED flags on our referenced vars.  In
+   theory, this only needs to be done for globals.  */
+
+static unsigned int
+reset_cc_flags (void)
+{
+  tree var;
+  referenced_var_iterator rvi;
+
+  FOR_EACH_REFERENCED_VAR (var, rvi)
+    DECL_CALL_CLOBBERED (var) = false;
+  return 0;
+}
+
+struct tree_opt_pass pass_reset_cc_flags =
+{
+  NULL,		 /* name */
+  NULL,  	 /* gate */
+  reset_cc_flags, /* execute */
+  NULL,			 /* sub */
+  NULL,			 /* next */
+  0,			 /* static_pass_number */
+  0,			 /* tv_id */
+  PROP_referenced_vars |PROP_cfg, /* properties_required */
+  0,			 /* properties_provided */
+  0,			 /* properties_destroyed */
+  0,			 /* todo_flags_start */
+  0,         	         /* todo_flags_finish */
+  0			 /* letter */
+};

gcc/tree-ssa.c

@@ -613,6 +613,46 @@ err:
 }
 
 
+/* Verify the consistency of call clobbering information.  */
+static void
+verify_call_clobbering (void)
+{
+  unsigned int i;
+  bitmap_iterator bi;
+  tree var;
+  referenced_var_iterator rvi;
+
+  /* At all times, the result of the DECL_CALL_CLOBBERED flag should
+     match the result of the call_clobbered_vars bitmap.  Verify both
+     that everything in call_clobbered_vars is marked
+     DECL_CALL_CLOBBERED, and that everything marked
+     DECL_CALL_CLOBBERED is in call_clobbered_vars.  */
+  EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, i, bi)
+    {
+      var = referenced_var (i);
+      if (!MTAG_P (var) && !DECL_CALL_CLOBBERED (var))
+	{
+	  error ("variable in call_clobbered_vars but not marked DECL_CALL_CLOBBERED");
+	  debug_variable (var);
+	  goto err;
+	}
+    }
+  FOR_EACH_REFERENCED_VAR (var, rvi)
+    {
+      if (!MTAG_P (var) && DECL_CALL_CLOBBERED (var)
+	  && !bitmap_bit_p (call_clobbered_vars, DECL_UID (var)))
+	{
+	  error ("variable marked DECL_CALL_CLOBBERED but not in call_clobbered_vars bitmap.");
+	  debug_variable (var);
+	  goto err;
+	}
+    }
+  return;
+
+ err:
+    internal_error ("verify_call_clobbering failed");
+}
+
 /* Verify the consistency of aliasing information.  */
 
 static void
@@ -620,6 +660,7 @@ verify_alias_info (void)
 {
   verify_flow_sensitive_alias_info ();
   verify_name_tags ();
+  verify_call_clobbering ();
   verify_flow_insensitive_alias_info ();
 }
 

gcc/tree.h

@@ -2486,6 +2486,12 @@ struct tree_struct_field_tag GTY(())
 #define DECL_COMPLEX_GIMPLE_REG_P(DECL) \
   DECL_COMMON_CHECK (DECL)->decl_common.gimple_reg_flag
 
+/* This is true if DECL is call clobbered in the current function.
+   The result of this flag should always be the same as
+   bitmap_bit_p (call_clobbered_vars, DECL_UID (decl)).  */
+#define DECL_CALL_CLOBBERED(DECL) \
+  DECL_COMMON_CHECK (DECL)->decl_common.call_clobbered_flag
+
 struct tree_decl_common GTY(())
 {
   struct tree_decl_minimal common;
@@ -2523,9 +2529,10 @@ struct tree_decl_common GTY(())
   /* In FIELD_DECL, this is DECL_NONADDRESSABLE_P
      In VAR_DECL and PARM_DECL, this is DECL_HAS_VALUE_EXPR.  */
   unsigned decl_flag_3 : 1;  
-  /* Logically, this would go in a theoretical base shared by var and parm 
-     decl. */
+  /* Logically, these two would go in a theoretical base shared by var and 
+     parm decl. */
   unsigned gimple_reg_flag : 1;
+  unsigned call_clobbered_flag : 1;
   
   union tree_decl_u1 {
     /* In a FUNCTION_DECL for which DECL_BUILT_IN holds, this is