re PR middle-end/40460 (Enormous memory usage during compilation with -O2 or -O3 optimizations.)

2009-06-17  Richard Guenther  <rguenther@suse.de>

	PR middle-end/40460
	* tree-chrec.h (build_polynomial_chrec): If we cannot determine
	if there is no evolution of left in the loop bail out.
	* tree-chrec.c (chrec_fold_multiply_poly_poly): CSE one
	chrec_fold_multiply.

	* g++.dg/torture/pr40460.C: New testcase.

From-SVN: r148593

gcc/ChangeLog

+2009-06-17  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/40460
+	* tree-chrec.h (build_polynomial_chrec): If we cannot determine
+	if there is no evolution of left in the loop bail out.
+	* tree-chrec.c (chrec_fold_multiply_poly_poly): CSE one
+	chrec_fold_multiply.
+
 2009-06-16  J"orn Rennecke  <joern.rennecke@arc.com>
 	    Janis Johnson  <janis187@us.ibm.com>
 

gcc/testsuite/ChangeLog

+2009-06-17  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/40460
+	* g++.dg/torture/pr40460.C: New testcase.
+
 2009-06-05  Olatunji Ruwase  <tjruwase@google.com>
 
 	* gcc.dg/plugin/one_time_plugin.c: New test.

gcc/testsuite/g++.dg/torture/pr40460.C

+/* { dg-do compile } */
+
+void bar(int);
+void foo(void)
+{
+  for (int i = 0; i<1; ++i)
+    bar (i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i*i);
+}
+

gcc/tree-chrec.c

@@ -220,16 +220,16 @@ chrec_fold_multiply_poly_poly (tree type,
   /* "a*c".  */
   t0 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1));
 
-  /* "a*d + b*c + b*d".  */
+  /* "a*d + b*c".  */
   t1 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_RIGHT (poly1));
   t1 = chrec_fold_plus (type, t1, chrec_fold_multiply (type,
 						       CHREC_RIGHT (poly0),
 						       CHREC_LEFT (poly1)));
-  t1 = chrec_fold_plus (type, t1, chrec_fold_multiply (type,
-						       CHREC_RIGHT (poly0),
-						       CHREC_RIGHT (poly1)));
-  /* "2*b*d".  */
+  /* "b*d".  */
   t2 = chrec_fold_multiply (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1));
+  /* "a*d + b*c + b*d".  */
+  t1 = chrec_fold_plus (type, t1, t2);
+  /* "2*b*d".  */
   t2 = chrec_fold_multiply (type, SCALAR_FLOAT_TYPE_P (type)
 			    ? build_real (type, dconst2)
 			    : build_int_cst (type, 2), t2);

gcc/tree-chrec.h

@@ -132,7 +132,8 @@ build_polynomial_chrec (unsigned loop_num,
       || right == chrec_dont_know)
     return chrec_dont_know;
 
-  if (no_evolution_in_loop_p (left, loop_num, &val) && !val)
+  if (!no_evolution_in_loop_p (left, loop_num, &val)
+      || !val)
     return chrec_dont_know;
 
   /* Pointer types should occur only on the left hand side, i.e. in