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

1 files changed, 56 insertions, 11 deletions

diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index 9bac292..83f0c36 100644
--- a/gcc/tree-ssa-operands.c
+++ b/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);
 	});
     }