unbreak cify on "startup.inc"

Commit 7cbeebbb89 broke the input to cify, and eb73837baf uncovered a
different problem.

racket/src/cify/generate.rkt

@@ -286,10 +286,14 @@
        (out-open "if (~a_count != 1)" vals-id)
        (return ret runstack #:can-omit? #t
                (format "scheme_values(~a_count, (Scheme_Object **)~a)" vals-id (runstack-ref runstack vals-id)))
-       (out-close+open "else")
-       (return ret runstack #:can-omit? #t #:can-pre-pop? #t
-               (runstack-ref runstack vals-id))
-       (out-close!)
+       (cond
+         [(return-can-omit-single? ret)
+          (out-close!)]
+         [else
+          (out-close+open "else")
+          (return ret runstack #:can-omit? #t #:can-pre-pop? #t
+                  (runstack-ref runstack vals-id))
+          (out-close!)])
        (runstack-pop! runstack)
        (out-close "}")]
       [`(if ,orig-tst ,thn ,els)
@@ -402,7 +406,7 @@
                                     (hash-ref top-names id #f)))
                               "/*needed*/"
                               ""))
-       (generate (multiple-return values-ret) `(begin . ,body1) env)
+       (generate (only-multiple-return values-ret) `(begin . ,body1) env)
        (out-open "{")
        (define bind-count
          (for/sum ([id (in-list ids)]
@@ -1041,7 +1045,7 @@
        (generate (format "~a =" (top-ref #f id)) rhs #f #hasheq()
                  runstack knowns top-names state lambdas prim-names prim-knowns)]
       [`(define-values (,ids ...) ,rhs)
-       (generate (multiple-return "/*needed*/") rhs #f #hasheq()
+       (generate (only-multiple-return "/*needed*/") rhs #f #hasheq()
                  runstack knowns top-names state lambdas prim-names prim-knowns)
        (generate-multiple-value-binds ids runstack #f state top-names)]
       [`,_

racket/src/cify/main.rkt

@@ -19,7 +19,8 @@
          "union.rkt"
          "debug.rkt")
 
-(provide (rename-out [main-cify cify]))
+(provide (rename-out [main-cify cify])
+         re-unique)
 
 (define (main-cify out-file exports in-e prim-knowns
                    #:debug? [debug? #f]

racket/src/cify/return.rkt

@@ -3,12 +3,15 @@
 
 (provide (struct-out tail-return)
          (struct-out multiple-return)
+         (struct-out only-multiple-return)
          (struct-out multiple-return/suffix)
          return
-         return-can-omit?)
+         return-can-omit?
+         return-can-omit-single?)
 
 (struct tail-return (function-id lam self-args leaf?))
 (struct multiple-return (prefix))
+(struct only-multiple-return multiple-return ())
 (struct multiple-return/suffix multiple-return (generate-suffix))
 
 (define (return ret runstack s
@@ -41,3 +44,5 @@
       (and (multiple-return? ret)
            (equal? (multiple-return-prefix ret) ""))))
 
+(define (return-can-omit-single? ret)
+  (only-multiple-return? ret))

racket/src/cify/unique.rkt

@@ -67,6 +67,9 @@
       [`(let . ,_) (re-unique-let e env)]
       [`(letrec . ,_) (re-unique-let e env)]
       [`(letrec* . ,_) (re-unique-let e env)]
+      ;; Recognize `values` form so we can use this on schemify input, too
+      [`(let-values . ,_) (re-unique-let-values e env)]
+      [`(letrec-values . ,_) (re-unique-let-values e env)]
       [`(set! ,id ,rhs)
        `(set! ,(re-unique id env) ,(re-unique rhs env))]
       [`(,rator ,rands ...)
@@ -92,6 +95,20 @@
                     `[,id ,(re-unique rhs rhs-env)])
                  . ,(re-unique-body body body-env))]))
 
+  (define (re-unique-let-values e env)
+    (match e
+      [`(,let-values-id ([(,idss ...) ,rhss] ...) . ,body)
+       (define rec? (not (eq? let-values-id 'let-values)))
+       (define new-idss (map select-unique idss))
+       (define body-env (for/fold ([env env]) ([ids (in-list idss)]
+                                               [new-ids (in-list new-idss)])
+                          (env-add env ids new-ids)))
+       (define rhs-env (if rec? body-env env))
+       `(,let-values-id ,(for/list ([ids (in-list new-idss)]
+                                    [rhs (in-list rhss)])
+                           `[,ids ,(re-unique rhs rhs-env)])
+                        . ,(re-unique-body body body-env))]))
+
   (define (env-add env ids new-ids)
     (cond
       [(null? ids) env]

racket/src/racket/src/cify-startup.rkt

@@ -66,10 +66,15 @@
 (define-values (bodys/constants-lifted lifted-constants)
   (time (convert-for-serialize l #t)))
 
+;; Startup code reuses names to keep it compact; make
+;; te names unique again
+(define bodys/re-uniqued
+  (cdr (re-unique `(begin . ,bodys/constants-lifted))))
+
 (printf "Schemify...\n")
 (define body
   (time
-   (schemify-body bodys/constants-lifted prim-knowns #hasheq() #hasheq()
+   (schemify-body bodys/re-uniqued prim-knowns #hasheq() #hasheq()
                   ;; for cify:
                   #t
                   ;; unsafe mode: