boot2

066-vararg-call.scm (2538B)

---

 ;; tests/cc-cg/66-vararg-call.scm — variadic call with default-promoted args (§G.1).
 ;; Models a variadic callee that just sums two int args after the named one.
 ;;   int sum_var(int n, ...) {
 ;;       int *ap = ((int*)(&n)) + 1;   /* hand-rolled vararg access */
 ;;       return n + ap[0] + ap[1];
 ;;   }
 ;;   int main(void) {
 ;;       signed char c = 5;
 ;;       short      s = 10;
 ;;       /* C semantics: c and s are promoted to int at the call site. */
 ;;       return sum_var(1, c, s);   /* 1 + 5 + 10 = 16 */
 ;;   }
 ;;
 ;; What the cc-cg fixture exercises is the *caller* side: cg-promote on
 ;; each variadic arg before cg-call. The callee uses fixed-arg ABI here
 ;; for simplicity; va_arg/va_start/va_end are §G.2.
 
 (let* ((cg          (cg-init))
        (sumv-fnty   (%ctype 'fn 8 8 (cons %t-i32 (cons (list %t-i32) #t))))
        (sumv-sym    (%sym "sum_var" 'fn 'extern sumv-fnty #f)))
   ;; int sum_var(int n, int a, int b) { return n + a + b; }
   ;; (Modeling 3 fixed params; the callee doesn't care about variadic
   ;; ABI in this fixture — see §G.2 for that.)
   (let* ((params (cg-fn-begin cg "sum_var"
                               (list (cons "n" %t-i32)
                                     (cons "a" %t-i32)
                                     (cons "b" %t-i32))
                               %t-i32))
          (n* (cdr (car params)))
          (a* (cdr (car (cdr params))))
          (b* (cdr (car (cdr (cdr params))))))
     (cg-push-sym cg n*) (cg-load cg)
     (cg-push-sym cg a*) (cg-load cg) (cg-binop cg 'add)
     (cg-push-sym cg b*) (cg-load cg) (cg-binop cg 'add)
     (cg-return cg)
     (cg-fn-end cg))
   ;; int main(void) { signed char c=5; short s=10; return sum_var(1, c, s); }
   (let* ((params (cg-fn-begin cg "main" '() %t-i32))
          (c-sl   (cg-alloc-slot cg 1 1))
          (s-sl   (cg-alloc-slot cg 2 2))
          (c-sym  (%sym "c" 'var 'auto %t-i8  c-sl))
          (s-sym  (%sym "s" 'var 'auto %t-i16 s-sl)))
     ;; c = 5;
     (cg-push-sym cg c-sym) (cg-push-imm cg %t-i32 5)
     (cg-assign cg) (cg-pop cg)
     ;; s = 10;
     (cg-push-sym cg s-sym) (cg-push-imm cg %t-i32 10)
     (cg-assign cg) (cg-pop cg)
     ;; sum_var(1, c, s) — promote c and s to int at the call site
     (cg-push-sym cg sumv-sym)
     (cg-push-imm cg %t-i32 1)               ; named-arg n
     (cg-push-sym cg c-sym) (cg-load cg) (cg-promote cg)   ; variadic c
     (cg-push-sym cg s-sym) (cg-load cg) (cg-promote cg)   ; variadic s
     (cg-call cg 3 #t)
     (cg-return cg)
     (cg-fn-end cg))
   (write-bv-fd 1 (cg-finish cg)))