make the optimizer slightly smarter, so that it can see through more patterns of nested let and letrec procedure bindings

svn: r12434

original commit: 59f3f19f84

collects/compiler/decompile.ss

@@ -40,7 +40,7 @@
 ;; Main entry:
 (define (decompile top)
   (match top
-    [(struct compilation-top (_ prefix form))
+    [(struct compilation-top (max-let-depth prefix form))
      (let-values ([(globs defns) (decompile-prefix prefix)])
        `(begin
           ,@defns
@@ -88,7 +88,7 @@
 
 (define (decompile-module mod-form stack)
   (match mod-form
-    [(struct mod (name self-modidx prefix provides requires body syntax-body))
+    [(struct mod (name self-modidx prefix provides requires body syntax-body max-let-depth))
      (let-values ([(globs defns) (decompile-prefix prefix)]
                   [(stack) (append '(#%modvars) stack)])
        `(module ,name ....

collects/compiler/zo-parse.ss

@@ -23,7 +23,7 @@
 ;; In stxs of prefix:
 (define-form-struct stx (encoded)) ; todo: decode syntax objects
 
-(define-form-struct mod (name self-modidx prefix provides requires body syntax-body))
+(define-form-struct mod (name self-modidx prefix provides requires body syntax-body max-let-depth))
 
 (define-form-struct lam (name flags num-params rest? closure-map max-let-depth body)) ; `lambda'
 (define-form-struct closure (code gen-id)) ; a static closure (nothing to close over)
@@ -220,7 +220,8 @@
                                    make-def-for-syntax
                                    make-def-syntaxes)
                                ids expr prefix max-let-depth)]))
-                         (vector->list syntax-body)))]))]))
+                         (vector->list syntax-body))
+                    max-let-depth)]))]))
 (define (read-module-wrap v)
   v)