[ARM][3/3] Expand mod by power of 2

[ARM][3/3] Expand mod by power of 2

	* config/arm/arm.md (*subsi3_compare0): Rename to...
	(subsi3_compare0): ... This.
	(modsi3): New define_expand.
	* config/arm/arm.c (arm_new_rtx_costs, MOD case): Handle case
	when operand is power of 2.

	* gcc.target/aarch64/mod_2.x: New file.
	* gcc.target/aarch64/mod_256.x: Likewise.
	* gcc.target/arm/mod_2.c: New test.
	* gcc.target/arm/mod_256.c: Likewise.
	* gcc.target/aarch64/mod_2.c: Likewise.
	* gcc.target/aarch64/mod_256.c: Likewise.

From-SVN: r227586