Re: Expanding an ADDSI3 into 2 x ADDHI3 does not work

[Paolo Bonzini]

If I use:
(define_expand "addsi"

addsi3

  "{
  emit_insn (gen_addhi3 (custom_subword(operands[0], 0, SImode),
                                                                 
custom_subword(operands[1], 0, SImode),
                                                                 
custom_subword(operands[2], 0, SImode)));
        emit_insn (gen_addhi3 (custom_subword(operands[0], 1, SImode),
                                                                 
custom_subword(operands[1], 1, SImode),
                                                                 
custom_subword(operands[2], 1, SImode)));

How can this work?  You need something like an adchi3 pattern.

Paolo