[PATCH] Fix PR66423

[Richard Biener]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2015-06-09  Richard Biener  <rguenther@suse.de>

	PR middle-end/66423
	* match.pd: Handle A % (unsigned)(1 << B).

	* gcc.dg/fold-modpow2.c: New testcase.

Index: gcc/match.pd
===================================================================
*** gcc/match.pd	(revision 224271)
--- gcc/match.pd	(working copy)
*************** (define_operator_list swapped_tcc_compar
*** 248,258 ****
   (lshift INTEGER_CST@1 @2))
  (for mod (trunc_mod floor_mod)
   (simplify
!   (mod @0 (power_of_two_cand@1 @2))
    (if ((TYPE_UNSIGNED (type)
  	|| tree_expr_nonnegative_p (@0))
  	&& integer_pow2p (@2) && tree_int_cst_sgn (@2) > 0)
!    (bit_and @0 (minus @1 { build_int_cst (TREE_TYPE (@1), 1); })))))
  
  /* X % Y is smaller than Y.  */
  (for cmp (lt ge)
--- 248,259 ----
   (lshift INTEGER_CST@1 @2))
  (for mod (trunc_mod floor_mod)
   (simplify
!   (mod @0 (convert?@3 (power_of_two_cand@1 @2)))
    (if ((TYPE_UNSIGNED (type)
  	|| tree_expr_nonnegative_p (@0))
+ 	&& tree_nop_conversion_p (type, TREE_TYPE (@3))
  	&& integer_pow2p (@2) && tree_int_cst_sgn (@2) > 0)
!    (bit_and @0 (convert (minus @1 { build_int_cst (TREE_TYPE (@1), 1); }))))))
  
  /* X % Y is smaller than Y.  */
  (for cmp (lt ge)
Index: gcc/testsuite/gcc.dg/fold-modpow2.c
===================================================================
*** gcc/testsuite/gcc.dg/fold-modpow2.c	(revision 0)
--- gcc/testsuite/gcc.dg/fold-modpow2.c	(working copy)
***************
*** 0 ****
--- 1,11 ----
+ /* { dg-do compile } */
+ /* { dg-options "-fdump-tree-original" } */
+ 
+ unsigned int
+ my_mod (unsigned int a, unsigned int b)
+ {
+   return a % (1 << b);
+ }
+ 
+ /* The above should be simplified to (unsigned int) ((1 << b) + -1) & a */
+ /* { dg-final { scan-tree-dump "& a;" "original" } } */