boot2

Playing with the boostrap
git clone https://git.ryansepassi.com/git/boot2.git
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021-preinc.scm (928B)

      1 ;; tests/cc-cg/21-preinc.scm — pre-increment on a simple lval (§B.1).
      2 ;;
      3 ;; Models: int x = 5; ++x; return x; → exit 6.
      4 ;;
      5 ;; The "++x" sequence requires the lhs lval to be preserved across
      6 ;; the load (so we can store back). cg-dup duplicates the top vstack
      7 ;; entry, giving us two lvals: one we load, one we keep for assign.
      8 
      9 (let ((cg (cg-init)))
     10   (cg-fn-begin cg "main" '() %t-i32)
     11   (let* ((off-x (cg-alloc-slot cg 4 4))
     12          (sym-x (%sym "x" 'var 'auto %t-i32 off-x)))
     13     ;; x = 5
     14     (cg-push-sym cg sym-x)
     15     (cg-push-imm cg %t-i32 5)
     16     (cg-assign cg) (cg-pop cg)
     17     ;; ++x:  push lval; dup; load; push 1; add; assign; pop result
     18     (cg-push-sym cg sym-x)
     19     (cg-dup cg)
     20     (cg-load cg)
     21     (cg-push-imm cg %t-i32 1)
     22     (cg-binop cg 'add)
     23     (cg-assign cg) (cg-pop cg)
     24     ;; return x
     25     (cg-push-sym cg sym-x)
     26     (cg-load cg)
     27     (cg-return cg))
     28   (cg-fn-end cg)
     29   (write-bv-fd 1 (cg-finish cg)))