New code to analyze file level static variables and to determine if...

New code to analyze file level static variables and to determine if
they escape and also code to use this information to prune clobber
lists.

From-SVN: r87455

gcc/ChangeLog

+2004-09-26  Kenneth Zadeck  <Kenneth.Zadeck@NaturalBridge.com>
+
+
+	* tree-ssa-operands.c (get_call_expr_operands): Added parm to
+	add_call_clobber_ops and add_call_read_ops.
+	(add_call_clobber_ops, add_call_read_ops): Added code to reduce
+	the number of vdefs and vuses inserted based on analysis of global
+	variables across calls.  * tree-dfa.c (find_referenced_vars):
+	Needed to reset static var maps before each function is compiled.
+	* cgraphunit.c:
+	(static_vars_to_consider_by_tree,static_vars_to_consider_by_uid,
+	static_vars_info,functions_to_static_vars_info,module_statics_escape,
+	all_module_statics,searchc_env,dfs_info): New fields to support
+	analysis of static global variables.
+	(print_order, convert_UIDs_in_bitmap, new_static_vars_info,
+	cgraph_reset_static_var_maps, get_global_static_vars_info,
+	get_global_statics_not_read, get_global_statics_not_written,
+	searchc, cgraph_reduced_inorder, has_proper_scope_for_analysis,
+	check_rhs_var, check_lhs_var, get_asm_expr_operands,
+	process_call_for_static_vars, scan_for_static_refs,
+	cgraph_characterize_statics_local, cgraph_get_static_name_by_uid,
+	clear_static_vars_maps, cgraph_propagate_bits,
+	cgraph_characterize_statics): New. Functions to support analysis
+	of static global variables.
+	(cgraph_mark_local_and_external_functions): Renamed from:
+	(cgraph_mark_local_functions)
+	(cgraph_expand_all_functions): Remove call to
+	cgraph_mark_local_and_external_functions.
+	(cgraph_optimize): Added driver to analyze static variables whose
+	scope is within the compilation unit.  * cgraph.h (struct
+	cgraph_local_info, GTY): Added statics_read, statics_written,
+	local, calls_read_all, calls_write_all, for_functions_valid.
+	(struct cgraph_node): Added next_cycle.  * cgraph.c
+	(dump_cgraph_node): Added print routines for new fields.  *
+	makefile.in: macroized cgraph.h, added cgraphunit.c to the ggc
+	list.
+
 2004-09-13  Joseph S. Myers  <jsm@polyomino.org.uk>
 
 	* c-decl.c (grokdeclarator): Correct comments about where storage

gcc/cgraph.c

@@ -474,6 +474,12 @@ dump_cgraph_node (FILE *f, struct cgraph_node *node)
 
   if (node->local.local)
     fprintf (f, " local");
+  if (node->local.external)
+    fprintf (f, " external");
+  if (node->local.calls_read_all)
+    fprintf (f, " calls_read_all");
+  if (node->local.calls_write_all)
+    fprintf (f, " calls_write_all");
   if (node->local.disregard_inline_limits)
     fprintf (f, " always_inline");
   else if (node->local.inlinable)

gcc/cgraph.h

@@ -22,6 +22,8 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #ifndef GCC_CGRAPH_H
 #define GCC_CGRAPH_H
 #include "hashtab.h"
+#include "bitmap.h"
+#include "tree.h"
 
 /* Information about the function collected locally.
    Available after function is analyzed.  */
@@ -30,19 +32,37 @@ struct cgraph_local_info GTY(())
 {
   /* Size of the function before inlining.  */
   int self_insns;
+
   /* Set when function function is visible in current compilation unit only
      and it's address is never taken.  */
   bool local;
+
+  /* Set when function is defined in another compilation unit.  */
+  bool external;
+
+  /* Set when this function calls a function external of the
+     compilation unit.  In general, such calls are modeled as reading
+     and writing all variables (both bits on) but sometime there are
+     attributes on the called function so we can do better.  */
+  bool calls_read_all;
+  bool calls_write_all;
+
   /* Set once it has been finalized so we consider it to be output.  */
   bool finalized;
 
   /* False when there something makes inlining impossible (such as va_arg).  */
   bool inlinable;
+
   /* True when function should be inlined independently on it's size.  */
   bool disregard_inline_limits;
+
   /* True when the function has been originally extern inline, but it is
      redefined now.  */
   bool redefined_extern_inline;
+
+  /* True if statics_read_for_function and
+     statics_written_for_function contain valid data.  */
+  bool for_functions_valid;
 };
 
 /* Information about the function that needs to be computed globally
@@ -70,6 +90,69 @@ struct cgraph_rtl_info GTY(())
    bool pure_function;
 };
 
+/* FIXME -- PROFILE-RESTRUCTURE: When the next round of the profiling
+   code gets merged in, it will contain a restructing where ssa form
+   is built for every function within the compilation unit before the
+   rest of the compilation continues.  When this reorgination is done,
+   it will no longer be necessary to have the _decl_uid versions of
+   local_static_vars_info and global_static_vars_info structures.
+   Having both structures is now requirred because the _ann_uid values
+   for static variables are reset as each function is compiled.
+   Currently, the analysis is done using the _decl_uid versions and
+   converted to the _var_ann versions on demand.
+
+   Also, the var_anns_valid fields within these structures can also go
+   away.
+*/
+
+/* The static variables defined within the compilation unit that are
+   loaded or stored directly by function that owns this structure.  */ 
+
+struct local_static_vars_info_d GTY(())
+{
+  bitmap statics_read_by_decl_uid;
+  bitmap statics_written_by_decl_uid;
+};
+
+struct global_static_vars_info_d GTY(())
+{
+  bitmap statics_read_by_decl_uid;
+  bitmap statics_written_by_decl_uid;
+  bitmap statics_read_by_ann_uid;
+  bitmap statics_written_by_ann_uid;
+  bitmap statics_not_read_by_decl_uid;
+  bitmap statics_not_written_by_decl_uid;
+  bitmap statics_not_read_by_ann_uid;
+  bitmap statics_not_written_by_ann_uid;
+
+  /* var_anns_valid is reset at the start of compilation for each
+     function because the indexing that the "_var_anns" is based
+     on is invalidated between function compilations.  This allows for
+     lazy creation of the "_var_ann" variables.  */
+  bool var_anns_valid;
+};
+
+/* Statics that are read and written by some set of functions. The
+   local ones are based on the loads and stores local to the function.
+   The global ones are based on the local info as well as the
+   transitive closure of the functions that are called.  The
+   structures are separated to allow the global structures to be
+   shared between several functions since every function within a
+   strongly connected component will have the same information.  This
+   sharing saves both time and space in the computation of the vectors
+   as well as their translation from decl_uid form to ann_uid
+   form.  */ 
+
+typedef struct local_static_vars_info_d *local_static_vars_info_t;
+typedef struct global_static_vars_info_d *global_static_vars_info_t;
+
+struct static_vars_info_d GTY(()) 
+{
+  local_static_vars_info_t local;
+  global_static_vars_info_t global;
+};
+
+typedef struct static_vars_info_d *static_vars_info_t;
 
 /* The cgraph data structure.
    Each function decl has assigned cgraph_node listing callees and callers.  */
@@ -91,11 +174,18 @@ struct cgraph_node GTY((chain_next ("%h.next"), chain_prev ("%h.previous")))
   struct cgraph_node *next_needed;
   /* Pointer to the next clone.  */
   struct cgraph_node *next_clone;
+  /* Pointer to next node in a recursive call graph cycle; */
+  struct cgraph_node *next_cycle;
   PTR GTY ((skip)) aux;
 
   struct cgraph_local_info local;
   struct cgraph_global_info global;
   struct cgraph_rtl_info rtl;
+  
+  /* Pointer to the structure that contains the sets of global
+     variables modified by function calls.  */
+  static_vars_info_t static_vars_info;
+
   /* Unique id of the node.  */
   int uid;
   /* Set when function must be output - it is externally visible
@@ -192,6 +282,9 @@ void verify_cgraph_node (struct cgraph_node *);
 void cgraph_mark_inline_edge (struct cgraph_edge *e);
 void cgraph_clone_inlined_nodes (struct cgraph_edge *e, bool duplicate);
 void cgraph_build_static_cdtor (char which, tree body, int priority);
+void cgraph_reset_static_var_maps (void);
+bitmap get_global_statics_not_read (tree fn);
+bitmap get_global_statics_not_written(tree fn);
 void init_cgraph (void);
 
 #endif  /* GCC_CGRAPH_H  */

gcc/tree-dfa.c

@@ -45,6 +45,7 @@ Boston, MA 02111-1307, USA.  */
 #include "tree-pass.h"
 #include "convert.h"
 #include "params.h"
+#include "cgraph.h"
 
 /* Build and maintain data flow information for trees.  */
 
@@ -107,6 +108,7 @@ find_referenced_vars (void)
   block_stmt_iterator si;
   struct walk_state walk_state;
 
+  cgraph_reset_static_var_maps ();
   vars_found = htab_create (50, htab_hash_pointer, htab_eq_pointer, NULL);
   memset (&walk_state, 0, sizeof (walk_state));
   walk_state.vars_found = vars_found;

gcc/tree-flow.h

@@ -28,6 +28,7 @@ Boston, MA 02111-1307, USA.  */
 #include "hashtab.h"
 #include "tree-gimple.h"
 #include "tree-ssa-operands.h"
+#include "cgraph.h"
 
 /* Forward declare structures for the garbage collector GTY markers.  */
 #ifndef GCC_BASIC_BLOCK_H
@@ -199,6 +200,11 @@ struct var_ann_d GTY(())
      live at the same time and this can happen for each call to the
      dominator optimizer.  */
   tree current_def;
+
+  /* Pointer to the structure that contains the sets of global
+     variables modified by function calls.  This field is only used
+     for FUNCTION_DECLs.  */
+  static_vars_info_t static_vars_info;
 };
 
 

gcc/tree-ssa-operands.c

@@ -32,7 +32,9 @@ Boston, MA 02111-1307, USA.  */
 #include "tree-pass.h"
 #include "ggc.h"
 #include "timevar.h"
+#include "cgraph.h"
 
+#include "langhooks.h"
 
 /* This file contains the code required to manage the operands cache of the 
    SSA optimizer.  For every stmt, we maintain an operand cache in the stmt 
@@ -133,8 +135,8 @@ static inline void append_def (tree *);
 static inline void append_use (tree *);
 static void append_v_may_def (tree);
 static void append_v_must_def (tree);
-static void add_call_clobber_ops (tree);
-static void add_call_read_ops (tree);
+static void add_call_clobber_ops (tree, tree);
+static void add_call_read_ops (tree, tree);
 static void add_stmt_operand (tree *, tree, int);
 
 /* Return a vector of contiguous memory for NUM def operands.  */
@@ -1380,6 +1382,7 @@ get_call_expr_operands (tree stmt, tree expr)
 {
   tree op;
   int call_flags = call_expr_flags (expr);
+  tree callee = get_callee_fndecl (expr);
 
   /* Find uses in the called function.  */
   get_expr_operands (stmt, &TREE_OPERAND (expr, 0), opf_none);
@@ -1396,9 +1399,9 @@ get_call_expr_operands (tree stmt, tree expr)
 	 there is no point in recording that.  */ 
       if (TREE_SIDE_EFFECTS (expr)
 	  && !(call_flags & (ECF_PURE | ECF_CONST | ECF_NORETURN)))
-	add_call_clobber_ops (stmt);
+	add_call_clobber_ops (stmt, callee);
       else if (!(call_flags & ECF_CONST))
-	add_call_read_ops (stmt);
+	add_call_read_ops (stmt, callee);
     }
 }
 
@@ -1562,7 +1565,7 @@ note_addressable (tree var, stmt_ann_t s_ann)
    clobbered variables in the function.  */
 
 static void
-add_call_clobber_ops (tree stmt)
+add_call_clobber_ops (tree stmt, tree callee)
 {
   /* Functions that are not const, pure or never return may clobber
      call-clobbered variables.  */
@@ -1579,16 +1582,53 @@ add_call_clobber_ops (tree stmt)
     {
       size_t i;
 
+      /* Get info for module level statics.  There is a bit set for
+	 each static if the call being processed does not read or
+	 write that variable.  */
+
+      bitmap not_read_b = callee 
+	? get_global_statics_not_read (callee) : NULL; 
+      bitmap not_written_b = callee 
+	? get_global_statics_not_written (callee) : NULL; 
+
+
       EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, i,
 	{
 	  tree var = referenced_var (i);
 
-	  /* If VAR is read-only, don't add a V_MAY_DEF, just a 
-	     VUSE operand.  */
-	  if (!TREE_READONLY (var))
-	    add_stmt_operand (&var, stmt, opf_is_def);
+	  bool not_read = not_read_b 
+	    ? bitmap_bit_p(not_read_b, i) : false;
+	  bool not_written = not_written_b
+	    ? bitmap_bit_p(not_written_b, i) : false;
+
+
+	  if (not_read) 
+	    { /* The var is not read during the call.  */
+	      if (not_written) 
+		{
+		  /* Nothing. */
+		}
+	      else 
+		add_stmt_operand (&var, stmt, opf_is_def);
+	    } 
 	  else
-	    add_stmt_operand (&var, stmt, opf_none);
+	    { /* The var is read during the call.  */
+	      if (not_written) 
+		add_stmt_operand (&var, stmt, opf_none);
+	      else 
+		/* The not_read and not_written bits are only set
+		   for module static variables.  Neither is set
+		   here, so we may be dealing with a module static
+		   or we may not.  So we still must look anywhere
+		   else we can (such as the TREE_READONLY) to get
+		   better info.  */
+		/* If VAR is read-only, don't add a V_MAY_DEF, just a 
+		   VUSE operand.  */
+		if (TREE_READONLY (var))
+		  add_stmt_operand (&var, stmt, opf_none);
+		else
+		  add_stmt_operand (&var, stmt, opf_is_def);
+	    }	      
 	});
     }
 }
@@ -1598,7 +1638,7 @@ add_call_clobber_ops (tree stmt)
    function.  */
 
 static void
-add_call_read_ops (tree stmt)
+add_call_read_ops (tree stmt, tree callee)
 {
   /* Otherwise, if the function is not pure, it may reference memory.  Add
      a VUSE for .GLOBAL_VAR if it has been created.  Otherwise, add a VUSE
@@ -1609,10 +1649,15 @@ add_call_read_ops (tree stmt)
   else
     {
       size_t i;
+      bitmap not_read_b = callee 
+	? get_global_statics_not_read (callee) : NULL; 
 
       EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, i,
 	{
 	  tree var = referenced_var (i);
+	  bool not_read = not_read_b 
+	    ? bitmap_bit_p(not_read_b, i) : false;
+	  if (!not_read)
 	  add_stmt_operand (&var, stmt, opf_none);
 	});
     }