impc:ir:compiler:if   scheme

;; if that might need to return a value
(define impc:ir:compiler:if
  (lambda (ast types . hint?)
    ;; (println 'ast: ast)
    (let* ((os (make-string 0))
           (elset (if (or (null? (cdddr ast))
                          (null? (cadddr ast)))
                      #f #t))
           (num (number->string (llvm:count++))))
      ;; first do compare expression
      (emit (impc:ir:compiler (cadr ast) types) os)
      ;; then break on compare
      (emit (string-append "br i1 " (car (impc:ir:gname)) ", label %then" num ", "
                           "label %else" num "\n") os)
      ;; do then
      (emit  "\nthen" num ":\n" os)
      (if (not (null? hint?))
          (emit (impc:ir:compiler (caddr ast) types (car hint?)) os)
          (emit (impc:ir:compiler (caddr ast) types) os))
      (if (not (impc:ir:void? (cadr (impc:ir:gname))))
          (emit (string-append "store " (cadr (impc:ir:gname)) " " (car (impc:ir:gname))
                               ", " (cadr (impc:ir:gname)) "* %ifptr" num "\n") os))
      (emit  "br label %ifcont" num "\n" os)
      (define a (impc:ir:gname))
      ;; do else if requried
      (if elset
          (begin (emit  "\nelse" num ":\n" os)
                 (if (not (null? hint?))
                     (emit (impc:ir:compiler (cadddr ast) types (car hint?)) os)
                     (emit (impc:ir:compiler (cadddr ast) types) os))
                 (if (not (impc:ir:void? (cadr (impc:ir:gname))))
                     (emit (string-append "store " (cadr (impc:ir:gname)) " " (car (impc:ir:gname))
                                          ", " (cadr (impc:ir:gname)) "* %ifptr" num "\n") os))
                 (emit  "br label %ifcont" num "\n" os))
          (begin (emit  "\nelse" num ":\n" os)
                 (emit  "br label %ifcont" num "\n" os)))