> Could someone give some hints of how to describe a FMAC (float mult and > add) insn in machine description, it matches d = b*c+a, which is a four > operands float instrution. With a glimp through the array optabs[] in > genopinit.c, it seems no OP handler could match FMAC operation?
Correct. It isn't generated directly during RTL generation, but instead created by the optimizer (combine) from add and multiply insns.
