re PR tree-optimization/18527 (cannot determine number of iterations for loops with <=)

	PR tree-optimization/18527
	* tree-ssa-loop-niter.c (number_of_iterations_cond,
	number_of_iterations_special, number_of_iterations_exit):
	Move base and step of an iv to a single structure.  Add
	no_overflow flag, and use it in # of iterations analysis.
	* tree-scalar-evolution.c (analyze_scalar_evolution_in_loop): Add
	folded_casts argument.
	(simple_iv): Pass base and step in a structure.  Set no_overflow
	flag.
	(scev_const_prop): Add argument to analyze_scalar_evolution_in_loop.
	Evaluate expensiveness of computing # of iterations instead of
	the final expression.
	* tree-scalar-evolution.h (affine_iv): New structure.
	(simple_iv): Declaration changed.
	* tree-chrec.c (chrec_apply): Handle chrecs containing symbols.
	* tree-ssa-loop-ivopts.c (determine_biv_step, find_givs_in_stmt_scev,
	find_givs_in_stmt): Changed due to simple_iv change.

	* gcc.dg/tree-ssa/loop-15.c: New test.

From-SVN: r109427

1 files changed, 6 insertions, 12 deletions

diff --git a/gcc/tree-chrec.c b/gcc/tree-chrec.c
index 0bf1d384592..30915d280ec 100644
--- a/gcc/tree-chrec.c
+++ b/gcc/tree-chrec.c
@@ -533,10 +533,9 @@ chrec_apply (unsigned var,
       /* When the symbols are defined in an outer loop, it is possible
 	 to symbolically compute the apply, since the symbols are
 	 constants with respect to the varying loop.  */
-      || chrec_contains_symbols_defined_in_loop (chrec, var)
-      || chrec_contains_symbols (x))
+      || chrec_contains_symbols_defined_in_loop (chrec, var))
     return chrec_dont_know;
-  
+ 
   if (dump_file && (dump_flags & TDF_DETAILS))
     fprintf (dump_file, "(chrec_apply \n");
 
@@ -546,14 +545,10 @@ chrec_apply (unsigned var,
   if (evolution_function_is_affine_p (chrec))
     {
       /* "{a, +, b} (x)"  ->  "a + b*x".  */
-      if (TREE_CODE (CHREC_LEFT (chrec)) == INTEGER_CST
-	  && integer_zerop (CHREC_LEFT (chrec)))
-	res = chrec_fold_multiply (type, CHREC_RIGHT (chrec), x);
-      
-      else
-	res = chrec_fold_plus (type, CHREC_LEFT (chrec), 
-			       chrec_fold_multiply (type, 
-						    CHREC_RIGHT (chrec), x));
+      x = chrec_convert (type, x, NULL_TREE);
+      res = chrec_fold_multiply (type, CHREC_RIGHT (chrec), x);
+      if (!integer_zerop (CHREC_LEFT (chrec)))
+	res = chrec_fold_plus (type, CHREC_LEFT (chrec), res);
     }
   
   else if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
@@ -563,7 +558,6 @@ chrec_apply (unsigned var,
 	   && tree_int_cst_sgn (x) == 1)
     /* testsuite/.../ssa-chrec-38.c.  */
     res = chrec_evaluate (var, chrec, x, 0);
-
   else
     res = chrec_dont_know;