* gcse.c (want_to_gcse_p): On STACK_REGS targets, look through
	constant pool references to identify stack mode constants.
	* rtlanal.c (constant_pool_constant_p): New predicate to check
	whether operand is a floating point constant in the pool.
	* rtl.h (constant_pool_constant_p): Prototype here.
	* loop.c (scan_loop): Avoid hoisting constants from the constant
	pool on STACK_REGS targets.
	(load_mems): Likewise.
	* loop-invariant.c (get_inv_cost): Make hoisting constant pool
	loads into x87 registers expensive in terms of register pressure.


Co-Authored-By: Steven Bosscher <stevenb.gcc@gmail.com>

From-SVN: r111283