PR tree-optimization/23452
	* fold-const.c (fold_mult_zconjz): New subroutine of fold_binary,
	to optimize z * conj(z) as realpart(z)^2 + imagpart(z)^2.
	(fold_binary) <MULT_EXPR>: Call fold_mult_zconjz for integral
	complex values and with -ffast-math for FP complex values.

	* gcc.dg/fold-mulconj-1.c: New test case.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@114246 138bc75d-0d04-0410-961f-82ee72b054a4