From b3bdb40ab739fe315d89ce1c9e6373ae43e46e5c Mon Sep 17 00:00:00 2001
From: Vincent St-Amour <stamourv@racket-lang.org>
Date: Tue, 24 Mar 2015 16:45:15 -0400
Subject: [PATCH] Optimize pair operations, even in the absence of syntactic
 pair types.

---
 .../typed-racket/optimizer/pair.rkt           | 10 +++--
 typed-racket-test/optimizer/tests/gh60.rkt    | 41 +++++++++++++++++++
 2 files changed, 47 insertions(+), 4 deletions(-)
 create mode 100644 typed-racket-test/optimizer/tests/gh60.rkt

diff --git a/typed-racket-lib/typed-racket/optimizer/pair.rkt b/typed-racket-lib/typed-racket/optimizer/pair.rkt
index a022ce21..0f90ec81 100644
--- a/typed-racket-lib/typed-racket/optimizer/pair.rkt
+++ b/typed-racket-lib/typed-racket/optimizer/pair.rkt
@@ -6,7 +6,7 @@
          (for-syntax racket/base syntax/parse racket/syntax)
          "../utils/utils.rkt"
          (rep type-rep)
-         (types type-table utils)
+         (types type-table utils base-abbrev)
          (typecheck typechecker)
          (optimizer utils logging))
 
@@ -25,9 +25,11 @@
 
 
 (define (has-pair-type? e)
-  (match (type-of e) ; type of the operand
-    [(tc-result1: (Pair: _ _)) #t]
-    [_ #f]))
+  (and (subtypeof? e (-pair Univ Univ))
+       ;; sometimes composite operations end up with Nothing as result type,
+       ;; not sure why. TODO investigate
+       (not (isoftype? e -Bottom))))
+;; can't do the above for mpairs, as they are invariant
 (define (has-mpair-type? e)
   (match (type-of e) ; type of the operand
     [(tc-result1: (MPair: _ _)) #t]
diff --git a/typed-racket-test/optimizer/tests/gh60.rkt b/typed-racket-test/optimizer/tests/gh60.rkt
new file mode 100644
index 00000000..9bed7945
--- /dev/null
+++ b/typed-racket-test/optimizer/tests/gh60.rkt
@@ -0,0 +1,41 @@
+#;#;
+#<<END
+TR opt: gh60.rkt 13:2 (car x) -- pair
+TR opt: gh60.rkt 20:2 (car x) -- pair
+TR opt: gh60.rkt 28:6 (car x) -- pair
+TR opt: gh60.rkt 29:6 (quote error) -- dead else branch
+TR opt: gh60.rkt 6:2 (car x) -- pair
+END
+""
+
+#lang typed/racket #:optimize
+#reader typed-racket-test/optimizer/reset-port
+
+(define-type foo (List Symbol Any))
+
+(: foo-car (foo . -> . Symbol))
+(define (foo-car x)
+  (car x))
+
+
+(define-type bar (List Symbol (U String bar)))
+
+(: bar-car (bar . -> . Symbol))
+(define (bar-car x)
+  (car x))
+
+
+(define-type zam (Rec z (List Symbol (U String z))))
+
+(: zam-car (zam . -> . Symbol))
+(define (zam-car x)
+  (car x))
+
+
+(define-type bar2 (List Symbol (U String bar)))
+
+(: bar2-car (bar2 . -> . Symbol))
+(define (bar2-car x)
+  (if (not (null? x))
+      (car x)
+      'error))