Report struct constructors used in hot code.

collects/typed-racket/optimizer/hidden-costs.rkt

@@ -6,6 +6,8 @@
          (optimizer utils logging)
          (types abbrev))
 
+(require (types type-table))
+
 (provide hidden-cost-log-expr)
 
 (define-syntax-class hidden-port-parameter-function
@@ -29,4 +31,11 @@
                           (syntax->list #'(args ...)))
            #:with opt
            (begin (log-optimization-info "hidden parameter" #'op)
+                  #`(op #,@(syntax-map (optimize) #'(args ...)))))
+  ;; Log calls to struct constructors, so that OC can report those used in
+  ;; hot loops.
+  (pattern (#%plain-app op:id args ...)
+           #:when (struct-constructor? #'op)
+           #:with opt
+           (begin (log-optimization-info "struct constructor" #'op)
                   #`(op #,@(syntax-map (optimize) #'(args ...))))))

collects/typed-racket/optimizer/tool/mzc.rkt

@@ -388,6 +388,24 @@
              '() '()
              20)))) ;; TODO have actual badness
 
+  (when inside-hot-function?
+    (for ([TR-entry (in-list TR-log)]
+          #:when (info-log-entry? TR-entry)
+          #:when (equal? (log-entry-kind TR-entry) "struct constructor")
+          #:when (pos-inside-us? (log-entry-pos TR-entry)))
+      (emit (missed-opt-log-entry
+             "" ; kind not used at this point
+             (string-append
+              "This struct constructor is used in hot code. "
+              "Allocating structs is expensive, consider using vectors instead. "
+              "To keep the same interface, consider defining macro wrappers "
+              "around the vector operations that have the same name as the "
+              "struct constructor and accessors.")
+             (log-entry-located-stx TR-entry) (log-entry-located-stx TR-entry)
+             (log-entry-pos TR-entry) 'typed-racket
+             '() '()
+             20)))) ;; TODO have actual badness
+
   produced-entries)
 
 (define (group-badness group)