tree.h (maybe_fold_offset_to_address): Declare.

2008-08-13  Richard Guenther  <rguenther@suse.de>

	* tree.h (maybe_fold_offset_to_address): Declare.
	* tree-ssa-ccp.c (surely_varying_stmt_p): Fix typo in last commit.
	(ccp_fold): Handle pointer conversions the same as fold_stmt.
	Likewise for POINTER_PLUS_EXPR.
	(maybe_fold_offset_to_reference): Enable disabled code.
	(maybe_fold_offset_to_address): New function.
	(fold_stmt_r): Use it.
	(fold_gimple_assign): Likewise.
	* gimplify.c (gimplify_conversion): Use maybe_fold_offset_to_address.
	(gimplify_expr): Likewise.

	* gcc.dg/tree-ssa/ssa-ccp-21.c: New testcase.
	* gcc.dg/tree-ssa/ssa-ccp-22.c: Likewise.
	* gcc.dg/tree-ssa/ssa-ccp-23.c: Likewise.

From-SVN: r139061

gcc/ChangeLog

+2008-08-13  Richard Guenther  <rguenther@suse.de>
+
+	* tree.h (maybe_fold_offset_to_address): Declare.
+	* tree-ssa-ccp.c (surely_varying_stmt_p): Fix typo in last commit.
+	(ccp_fold): Handle pointer conversions the same as fold_stmt.
+	Likewise for POINTER_PLUS_EXPR.
+	(maybe_fold_offset_to_reference): Enable disabled code.
+	(maybe_fold_offset_to_address): New function.
+	(fold_stmt_r): Use it.
+	(fold_gimple_assign): Likewise.
+	* gimplify.c (gimplify_conversion): Use maybe_fold_offset_to_address.
+	(gimplify_expr): Likewise.
+
 2008-08-13  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
 
 	* toplev.h (pedwarn_at): Fix declaration.

gcc/gimplify.c

@@ -1842,17 +1842,13 @@ gimplify_conversion (tree *expr_p)
   /* Attempt to avoid NOP_EXPR by producing reference to a subtype.
      For example this fold (subclass *)&A into &A->subclass avoiding
      a need for statement.  */
-  if (TREE_CODE (*expr_p) == NOP_EXPR
+  if (CONVERT_EXPR_P (*expr_p)
       && POINTER_TYPE_P (TREE_TYPE (*expr_p))
       && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (*expr_p, 0)))
-      && (tem = maybe_fold_offset_to_reference
+      && (tem = maybe_fold_offset_to_address
 		  (TREE_OPERAND (*expr_p, 0),
-		   integer_zero_node, TREE_TYPE (TREE_TYPE (*expr_p)))))
-    {
-      tree ptr_type = build_pointer_type (TREE_TYPE (tem));
-      if (useless_type_conversion_p (TREE_TYPE (*expr_p), ptr_type))
-        *expr_p = build_fold_addr_expr_with_type (tem, ptr_type);
-    }
+		   integer_zero_node, TREE_TYPE (*expr_p))) != NULL_TREE)
+    *expr_p = tem;
 
   /* If we still have a conversion at the toplevel,
      then canonicalize some constructs.  */
@@ -6735,30 +6731,24 @@ gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
 	     The second is gimple immediate saving a need for extra statement.
 	   */
 	  if (TREE_CODE (TREE_OPERAND (*expr_p, 1)) == INTEGER_CST
-	      && (tmp = maybe_fold_offset_to_reference
+	      && (tmp = maybe_fold_offset_to_address
 			 (TREE_OPERAND (*expr_p, 0), TREE_OPERAND (*expr_p, 1),
-		   	  TREE_TYPE (TREE_TYPE (*expr_p)))))
-	     {
-	       tree ptr_type = build_pointer_type (TREE_TYPE (tmp));
-	       if (useless_type_conversion_p (TREE_TYPE (*expr_p), ptr_type))
-		 {
-                   *expr_p = build_fold_addr_expr_with_type (tmp, ptr_type);
-		   break;
-		 }
-	     }
+		   	  TREE_TYPE (*expr_p))))
+	    {
+	      *expr_p = tmp;
+	      break;
+	    }
 	  /* Convert (void *)&a + 4 into (void *)&a[1].  */
 	  if (TREE_CODE (TREE_OPERAND (*expr_p, 0)) == NOP_EXPR
 	      && TREE_CODE (TREE_OPERAND (*expr_p, 1)) == INTEGER_CST
 	      && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (*expr_p,
 									0),0)))
-	      && (tmp = maybe_fold_offset_to_reference
+	      && (tmp = maybe_fold_offset_to_address
 			 (TREE_OPERAND (TREE_OPERAND (*expr_p, 0), 0),
 			  TREE_OPERAND (*expr_p, 1),
-		   	  TREE_TYPE (TREE_TYPE
-				  (TREE_OPERAND (TREE_OPERAND (*expr_p, 0),
-						 0))))))
+		   	  TREE_TYPE (TREE_OPERAND (TREE_OPERAND (*expr_p, 0),
+						   0)))))
 	     {
-               tmp = build_fold_addr_expr (tmp);
                *expr_p = fold_convert (TREE_TYPE (*expr_p), tmp);
 	       break;
 	     }

gcc/testsuite/ChangeLog

+2008-08-13  Richard Guenther  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/ssa-ccp-21.c: New testcase.
+	* gcc.dg/tree-ssa/ssa-ccp-22.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-ccp-23.c: Likewise.
+
 2008-08-13  Samuel Tardieu  <sam@rfc1149.net>
 
 	PR ada/36777

gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-21.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+struct A {
+    struct B {
+	int i;
+    } b;
+} a;
+
+int foo (void)
+{
+  struct B *p = &a.b;
+  struct A *q = (struct A *) p;
+  return q->b.i;
+}
+
+int bar (void)
+{
+  struct A *p = &a;
+  struct B *q = (struct B *) p;
+  return q->i;
+}
+
+/* { dg-final { scan-tree-dump-times "a.b.i" 2 "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-22.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+/* Make sure we propagate through builtins.  */
+
+int foo (unsigned b)
+{
+  unsigned t = -1;
+  int x = b <= t;
+  long l = __builtin_expect (x, 0);
+  return l;
+}
+
+/* { dg-final { scan-tree-dump "return 1;" "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-23.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+/* Make sure we propagate through POINTER_PLUS_EXPRs.  */
+
+struct A {
+  int i[2];
+} a;
+
+int foo (void)
+{
+  struct A *p = &a;
+  int *q = (int *)p;
+  int *x = q + 1;
+  return *x;
+}
+
+/* { dg-final { scan-tree-dump "a.i\\\[1\\\]" "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */

gcc/tree-ssa-ccp.c

@@ -630,7 +630,7 @@ surely_varying_stmt_p (gimple stmt)
       tree fndecl;
       if (!gimple_call_lhs (stmt)
 	  || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
-	      && DECL_BUILT_IN (fndecl)))
+	      && !DECL_BUILT_IN (fndecl)))
 	return true;
     }
 
@@ -988,18 +988,26 @@ ccp_fold (gimple stmt)
 		 useless_type_conversion_p places for pointer type conversions
 		 do not apply here.  Substitution later will only substitute to
 		 allowed places.  */
-              if ((subcode == NOP_EXPR || subcode == CONVERT_EXPR)
-		  && ((POINTER_TYPE_P (TREE_TYPE (lhs))
-		       && POINTER_TYPE_P (TREE_TYPE (op0))
-		       /* Do not allow differences in volatile qualification
-			  as this might get us confused as to whether a
-			  propagation destination statement is volatile
-			  or not.  See PR36988.  */
-		       && (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (lhs)))
-			   == TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (op0)))))
-		      || useless_type_conversion_p (TREE_TYPE (lhs),
-						    TREE_TYPE (op0))))
-                return op0;
+	      if (IS_CONVERT_EXPR_CODE_P (subcode)
+		  && POINTER_TYPE_P (TREE_TYPE (lhs))
+		  && POINTER_TYPE_P (TREE_TYPE (op0))
+		  /* Do not allow differences in volatile qualification
+		     as this might get us confused as to whether a
+		     propagation destination statement is volatile
+		     or not.  See PR36988.  */
+		  && (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (lhs)))
+		      == TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (op0)))))
+		{
+		  tree tem;
+		  /* Still try to generate a constant of correct type.  */
+		  if (!useless_type_conversion_p (TREE_TYPE (lhs),
+						  TREE_TYPE (op0))
+		      && ((tem = maybe_fold_offset_to_address
+				   (op0, integer_zero_node, TREE_TYPE (lhs)))
+			  != NULL_TREE))
+		    return tem;
+		  return op0;
+		}
 
               return fold_unary (subcode, gimple_expr_type (stmt), op0);
             }  
@@ -1025,6 +1033,18 @@ ccp_fold (gimple stmt)
                     op1 = val->value;
                 }
 
+	      /* Fold &foo + CST into an invariant reference if possible.  */
+	      if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
+		  && TREE_CODE (op0) == ADDR_EXPR
+		  && TREE_CODE (op1) == INTEGER_CST)
+		{
+		  tree lhs = gimple_assign_lhs (stmt);
+		  tree tem = maybe_fold_offset_to_address (op0, op1,
+							   TREE_TYPE (lhs));
+		  if (tem != NULL_TREE)
+		    return tem;
+		}
+
               return fold_binary (subcode, gimple_expr_type (stmt), op0, op1);
             }
 
@@ -1948,15 +1968,15 @@ maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type)
 	 so it needs to be removed and new COMPONENT_REF constructed.
 	 The wrong COMPONENT_REF are often constructed by folding the
 	 (type *)&object within the expression (type *)&object+offset  */
-      if (handled_component_p (base) && 0)
+      if (handled_component_p (base))
 	{
           HOST_WIDE_INT sub_offset, size, maxsize;
 	  tree newbase;
 	  newbase = get_ref_base_and_extent (base, &sub_offset,
 					     &size, &maxsize);
 	  gcc_assert (newbase);
-	  gcc_assert (!(sub_offset & (BITS_PER_UNIT - 1)));
-	  if (size == maxsize)
+	  if (size == maxsize
+	      && !(sub_offset & (BITS_PER_UNIT - 1)))
 	    {
 	      base = newbase;
 	      if (sub_offset)
@@ -1988,6 +2008,63 @@ maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type)
   return ret;
 }
 
+/* Attempt to express (ORIG_TYPE)&BASE+OFFSET as &BASE->field_of_orig_type
+   or &BASE[index] or by combination of those.
+
+   Before attempting the conversion strip off existing component refs.  */
+
+tree
+maybe_fold_offset_to_address (tree addr, tree offset, tree orig_type)
+{
+  tree t;
+
+  gcc_assert (POINTER_TYPE_P (TREE_TYPE (addr))
+	      && POINTER_TYPE_P (orig_type));
+
+  t = maybe_fold_offset_to_reference (addr, offset, TREE_TYPE (orig_type));
+  if (t != NULL_TREE)
+    {
+      tree orig = addr;
+      tree ptr_type;
+
+      /* For __builtin_object_size to function correctly we need to
+         make sure not to fold address arithmetic so that we change
+	 reference from one array to another.  This would happen for
+	 example for
+
+	   struct X { char s1[10]; char s2[10] } s;
+	   char *foo (void) { return &s.s2[-4]; }
+
+	 where we need to avoid generating &s.s1[6].  As the C and
+	 C++ frontends create different initial trees
+	 (char *) &s.s1 + -4  vs.  &s.s1[-4]  we have to do some
+	 sophisticated comparisons here.  Note that checking for the
+	 condition after the fact is easier than trying to avoid doing
+	 the folding.  */
+      STRIP_NOPS (orig);
+      if (TREE_CODE (orig) == ADDR_EXPR)
+	orig = TREE_OPERAND (orig, 0);
+      if ((TREE_CODE (orig) == ARRAY_REF
+	   || (TREE_CODE (orig) == COMPONENT_REF
+	       && TREE_CODE (TREE_TYPE (TREE_OPERAND (orig, 1))) == ARRAY_TYPE))
+	  && (TREE_CODE (t) == ARRAY_REF
+	      || (TREE_CODE (t) == COMPONENT_REF
+		  && TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 1))) == ARRAY_TYPE))
+	  && !operand_equal_p (TREE_CODE (orig) == ARRAY_REF
+			       ? TREE_OPERAND (orig, 0) : orig,
+			       TREE_CODE (t) == ARRAY_REF
+			       ? TREE_OPERAND (t, 0) : t, 0))
+	return NULL_TREE;
+
+      ptr_type = build_pointer_type (TREE_TYPE (t));
+      if (!useless_type_conversion_p (orig_type, ptr_type))
+	return NULL_TREE;
+      return build_fold_addr_expr_with_type (t, ptr_type);
+    }
+
+  return NULL_TREE;
+}
+
 /* A subroutine of fold_stmt_r.  Attempt to simplify *(BASE+OFFSET).
    Return the simplified expression, or NULL if nothing could be done.  */
 
@@ -2223,16 +2300,10 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
 
       if (POINTER_TYPE_P (TREE_TYPE (expr))
 	  && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
-	  && (t = maybe_fold_offset_to_reference
-		      (TREE_OPERAND (expr, 0),
-		       integer_zero_node,
-		       TREE_TYPE (TREE_TYPE (expr)))))
-	{
-	  tree ptr_type = build_pointer_type (TREE_TYPE (t));
-	  if (!useless_type_conversion_p (TREE_TYPE (expr), ptr_type))
-	    return NULL_TREE;
-          t = build_fold_addr_expr_with_type (t, ptr_type);
-	}
+	  && (t = maybe_fold_offset_to_address (TREE_OPERAND (expr, 0),
+						integer_zero_node,
+						TREE_TYPE (TREE_TYPE (expr)))))
+	return t;
       break;
 
       /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
@@ -2715,15 +2786,10 @@ fold_gimple_assign (gimple_stmt_iterator *si)
 	       && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))))
 	{
 	  tree type = gimple_expr_type (stmt);
-	  tree t = maybe_fold_offset_to_reference (gimple_assign_rhs1 (stmt),
-						   integer_zero_node,
-						   TREE_TYPE (type));
+	  tree t = maybe_fold_offset_to_address (gimple_assign_rhs1 (stmt),
+						 integer_zero_node, type);
 	  if (t)
-	    {
-	      tree ptr_type = build_pointer_type (TREE_TYPE (t));
-	      if (useless_type_conversion_p (type, ptr_type))
-		return build_fold_addr_expr_with_type (t, ptr_type);
-	    }
+	    return t;
 	}
       break;
 

gcc/tree.h

@@ -4744,6 +4744,7 @@ extern void fold_undefer_overflow_warnings (bool, const_gimple, int);
 extern void fold_undefer_and_ignore_overflow_warnings (void);
 extern bool fold_deferring_overflow_warnings_p (void);
 extern tree maybe_fold_offset_to_reference (tree, tree, tree);
+extern tree maybe_fold_offset_to_address (tree, tree, tree);
 extern tree maybe_fold_stmt_addition (tree, tree, tree);
 
 extern tree force_fit_type_double (tree, unsigned HOST_WIDE_INT, HOST_WIDE_INT,