re PR target/33604 (Revision 119502 causes significantly slower results with 4.3/4.4 compared to 4.2)

2007-11-09  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/33604
	* tree-ssa-forwprop.c (tree_ssa_forward_propagate_single_use_vars):
	Disregard changes in CV qualifiers of pointed to types for
	forward propagating ADDR_EXPRs.
	* tree-ssa-ccp.c (fold_stmt_r): Preserve volatileness of the original
	expression.

	* g++.dg/tree-ssa/pr33604.C: New testcase.
	* gcc.dg/pr32721.c: Adjust pattern.

From-SVN: r130040

gcc/ChangeLog

@@ -1,3 +1,12 @@
+2007-11-09  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/33604
+	* tree-ssa-forwprop.c (tree_ssa_forward_propagate_single_use_vars):
+	Disregard changes in CV qualifiers of pointed to types for
+	forward propagating ADDR_EXPRs.
+	* tree-ssa-ccp.c (fold_stmt_r): Preserve volatileness of the original
+	expression.
+
 2007-11-09  Richard Sandiford  <rsandifo@nildram.co.uk>
 
 	* dse.c (find_shift_sequence): Always choose an integer mode for

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2007-11-09  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/33604
+	* g++.dg/tree-ssa/pr33604.C: New testcase.
+	* gcc.dg/pr32721.c: Adjust pattern.
+
 2007-11-09  Richard Sandiford  <rsandifo@nildram.co.uk>
 
 	* gcc.target/mips/dse-1.c: Disable.

gcc/testsuite/g++.dg/tree-ssa/pr33604.C

@@ -0,0 +1,46 @@
+/* { dg-do run } */
+/* { dg-options "-O -fdump-tree-forwprop1" } */
+
+struct Value
+{
+  double value;
+  Value(double value_) : value (value_) {}
+  operator double() const { return value; }
+  Value& operator=(double other) { value = other; }
+};
+
+struct Ref
+{
+  const Value& m;
+  Ref(const Value& m_) : m(m_) {}
+  operator double() const { return m; }
+};
+
+struct Diff
+{
+  const Ref lhs, rhs;
+  Diff(const Value& lhs_, const Value& rhs_) : lhs(lhs_), rhs(rhs_) {}
+  operator double() const { return lhs - rhs; }
+};
+
+extern "C" void abort (void);
+int main(int argc, char *argv[])
+{
+  Value I(1), m(4);
+  for(int a = 0; a < 1000; a++)
+    m = Diff (I, m);
+
+  if (!(m / 4 == I))
+    abort ();
+  return 0;
+}
+
+/* Check that we forward propagated
+     D.2182_13 = (struct Ref *) &D.2137.lhs;
+   to
+     D.2182_13->lhs.m ={v} &I;
+   yielding
+     D.2137.lhs.m ={v} &I;  */
+
+/* { dg-final { scan-tree-dump-times "D\\\.....\\\..hs\\\.m =" 2 "forwprop1" } } */
+/* { dg-final { cleanup-tree-dump "forwprop1" } } */

gcc/testsuite/gcc.dg/pr32721.c

@@ -14,5 +14,6 @@ spinlock1 = &spinlock[1];
  while (*spinlock0);
 }
 
-/* { dg-final { scan-tree-dump "={v} \\*spinlock0" "optimized" } } */
+/* { dg-final { scan-tree-dump "={v} .*spinlock" "optimized" } } */
+/* { dg-final { scan-tree-dump "spinlock.* ={v}" "optimized" } } */
 /* { dg-final { cleanup-tree-dump "optimized" } } */

gcc/tree-ssa-ccp.c

@@ -2034,6 +2034,7 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
   bool *inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p;
   bool *changed_p = fold_stmt_r_data->changed_p;
   tree expr = *expr_p, t;
+  bool volatile_p = TREE_THIS_VOLATILE (expr);
 
   /* ??? It'd be nice if walk_tree had a pre-order option.  */
   switch (TREE_CODE (expr))
@@ -2159,6 +2160,8 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
 
   if (t)
     {
+      /* Preserve volatileness of the original expression.  */
+      TREE_THIS_VOLATILE (t) = volatile_p;
       *expr_p = t;
       *changed_p = true;
     }

gcc/tree-ssa-forwprop.c

@@ -952,7 +952,15 @@ tree_ssa_forward_propagate_single_use_vars (void)
 		  continue;
 		}
 
-	      if (TREE_CODE (rhs) == ADDR_EXPR)
+	      if (TREE_CODE (rhs) == ADDR_EXPR
+		  /* We can also disregard changes in CV qualifiers for
+		     the dereferenced value.  */
+		  || ((TREE_CODE (rhs) == NOP_EXPR
+		       || TREE_CODE (rhs) == CONVERT_EXPR)
+		      && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR
+		      && POINTER_TYPE_P (TREE_TYPE (rhs))
+		      && useless_type_conversion_p (TREE_TYPE (TREE_TYPE (rhs)),
+						    TREE_TYPE (TREE_TYPE (TREE_OPERAND (rhs, 0))))))
 		{
 		  if (forward_propagate_addr_expr (lhs, rhs))
 		    {