From 639c992ea2c89ef0b6421279a76e637c7f469517 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke_lau@icloud.com>
Date: Sat, 17 Aug 2019 19:43:44 +0100
Subject: [PATCH] Store ADTs with only singletons in registers

Also define Bool as an ADT within the stdlib!
---
 ast.scm       |   1 -
 codegen.scm   | 104 +++++++++++++++++++++++++++++---------------------
 stdlib.scm    |   4 ++
 tests.scm     |  34 +++++++++++++----
 typecheck.scm |   7 ++--
 5 files changed, 95 insertions(+), 55 deletions(-)
 create mode 100644 stdlib.scm

diff --git a/ast.scm b/ast.scm
index eabad58..c32e47e 100644
--- a/ast.scm
+++ b/ast.scm
@@ -25,7 +25,6 @@
    ((builtin? x) 'builtin)
    ((symbol? x) 'var)
    ((integer? x) 'int-literal)
-   ((boolean? x) 'bool-literal)
    ((string? x) 'string-literal)))
 
 (define (ast-traverse f x)
diff --git a/codegen.scm b/codegen.scm
index 985ad44..7518d83 100644
--- a/codegen.scm
+++ b/codegen.scm
@@ -1,6 +1,7 @@
 (load "typecheck.scm")
 (load "ast.scm")
 (load "platform.scm")
+(load "stdlib.scm")
 
 (define target host-os)
 
@@ -11,9 +12,12 @@
 
 (define wordsize 8)
 
-(define (stack-type? data-layouts type)
-  (if (assoc type data-layouts) #t #f))
+(define (stack-type? dls type)
+  (if (adt? dls type)      
+      (> (type-size dls type) wordsize)
+      #f))
 
+(define (adt? data-layouts type) (assoc type data-layouts))
 
 (define (type-size data-layouts type)
 
@@ -28,13 +32,22 @@
   
   (case type
     ['Int wordsize]
-    ['Bool wordsize]
     [else
      (let ([adt (assoc type data-layouts)])
        (if adt
 	   (adt-size adt)
 	   (error #f "unknown size" type)))]))
 
+(define (singletons dls)
+  (flat-map
+   (lambda (sums)
+     (fold-left append '()
+		(filter (lambda (x) (= 1 (length x))) sums)))
+   (map cdr dls)))
+
+(define (singleton? dls x)
+  (memv x (singletons dls)))
+
 					; returns the size of an expression's result in bytes
 (define (expr-size dls e)
   (if (eqv? (ast-type e) 'stack)
@@ -253,25 +266,22 @@
 
 	 [dls (env-data-layouts env)]
 	 
-	 [singleton? (and stack-type
-			(assoc name
-			       (cdr (assoc stack-type dls))))]
 				    
 	 [stack-offset (assoc name (env-bindings env))])
+
     (when (and (not stack-offset) (not singleton?))
       (error #f (format "Variable ~a is not bound" name)))
 
-    (if (on-stack? e)
-	(if singleton?
+    (cond
+     [(singleton? dls name)
       					; singletons don't need to be in the environment
-					; just copy over the tag
-	    (emit "movq $~a, ~a(%rbp)"
-		  (data-sum-tag (env-data-layouts env)
-				stack-type
-				name)
-		  si)
-	    (emit-stack-copy (cdr stack-offset) si (type-size dls stack-type)))
-	(emit "movq ~a(%rbp), %rax" (cdr stack-offset)))))
+					; just store the tag
+      (let ([tag (data-sum-tag (env-data-layouts env) name)])
+	(if (on-stack? e)
+	    (emit "movq $~a, ~a(%rbp)" tag si)
+	    (emit "movq $~a, %rax" tag)))]
+     [(on-stack? e) (emit-stack-copy (cdr stack-offset) si (type-size dls stack-type))]
+     [else (emit "movq ~a(%rbp), %rax" (cdr stack-offset))])))
 
 (define cur-lambda 0)
 (define (fresh-lambda)
@@ -370,9 +380,10 @@
 (define (codegen-lambda l)
   (let* ((label (car l))
 	 (stuff (cdr l))
-	 (captives (car stuff))
-	 (args (cadr stuff))
-	 (body (caddr stuff))
+	 (dls (car stuff))
+	 (captives (cadr stuff))
+	 (args (caddr stuff))
+	 (body (cadddr stuff))
 					; params = what actually gets passed
 	 (params (append captives args))
 
@@ -381,7 +392,7 @@
 			     (range 0 (length params))))
 
 	 [bindings (map cons params stack-offsets)]
-	 [env (make-env '() bindings)])
+	 [env (make-env dls bindings)])
     (emit "~a:" label)
 
     (display "## lambda captives: ")
@@ -473,10 +484,9 @@
 			 (range 0 (length (cdr x))))))))
 	     
 
-    (let ([sums (assoc type dls)])
-      (if sums
+    (if (adt? dls type)
 	(let* ([sum (if (list? x) (car x) x)] ; can sometimes be a singleton
-		 [tag (data-sum-tag dls type sum)])
+	       [tag (data-sum-tag dls sum)])
 					; the tag is at the top (beginning) of the adt on the stack
 	  (emit "cmpq $~a, ~a(%rbp)" tag inner-offset)
 	  (emit "jne ~a" jne-label)
@@ -492,9 +502,10 @@
 	(if (eqv? 'var (ast-type x))
 	    (list (cons x inner-offset))
 	    (begin
+;	      (display "LITERALliteral\n")
 	      (emit "cmpq $~a, ~a(%rbp)" x inner-offset)
 	      (emit "jne ~a" jne-label)
-		'() )))))
+	      '() ))))
   
   (define (codegen-adt-match type case)
     (let* ([match (car case)]
@@ -511,8 +522,12 @@
       (emit "~a:" next-section-label)))
 
   (define (codegen-literal-match case)
-    (let ([next-section-label (fresh-label)])
-      (emit "cmpq $~a, %rax" (car case))
+    (let* ([next-section-label (fresh-label)]
+	   [match (car case)]
+	   [val (if (singleton? dls match)
+		    (data-sum-tag dls match)
+		    match)])
+      (emit "cmpq $~a, %rax" val)
       (emit "jne ~a" next-section-label)
       (codegen-expr (cadr case) si env)
       (emit "jmp ~a" exit-label)
@@ -522,7 +537,7 @@
 					; (and store it on the stack if not a stack value)
   (codegen-expr switch si env)
 
-  (if (eqv? 'stack (ast-type switch))
+  (if (on-stack? switch)
 					; adt pattern match
       (for-each (lambda (x) (codegen-adt-match (cadr switch) x)) cases)
       (for-each codegen-literal-match cases))
@@ -544,14 +559,16 @@
      wordsize ; skip the tag in the first word
      to-traverse)))
 
-(define (data-sum-tag data-layouts type sum)
+(define (data-sum-tag data-layouts sum)
 
   (define (go acc sums)
     (when (null? sums) (error #f "data-sum-tag no sum for type" sum type))
     (if (eqv? sum (car sums))
 	acc
 	(go (+ 1 acc) (cdr sums))))
-  (let* ([type-sums (cdr (assoc type data-layouts))])
+  (let* ([all-sum-names (flat-map (lambda (x) (map (lambda (y) (cons (car y) (car x))) (cdr x))) data-layouts)]
+	 [type (cdr (assoc sum all-sum-names))]
+	 [type-sums (cdr (assoc type data-layouts))])
     (go 0 (map car type-sums))))
 
 (define (codegen-data-tor e si env)
@@ -594,7 +611,6 @@
 	   [args (cdr e)]
 
 	   [tag (data-sum-tag (env-data-layouts env)
-			      type
 			      sum)]
 
 	   [inner-si (- si (type-size dls type))]
@@ -670,21 +686,19 @@
 					; takes in a expr annotated with types and returns a type-less AST
 					; with stack values wrapped
 (define (annotate-stack-values data-layouts ann-e)
-  (define (stack-type? type)
-    (assoc type data-layouts))
   (define (strip e)
     (ast-traverse strip (ann-expr e)))
   (let* ([e (ann-expr ann-e)]
 	 [type (ann-type ann-e)])
-    (if (stack-type? type)
+    (if (stack-type? data-layouts type)
 	`(stack ,type
 		,(ast-traverse (lambda (x) (annotate-stack-values data-layouts x)) e))
 	(ast-traverse (lambda (x)
 			(annotate-stack-values data-layouts x))
 		      e))))
 
-(define (free-vars prog)
-  (define bound '())
+(define (free-vars dls prog)
+  (define bound (singletons dls))
   (define (collect e)
     (case (ast-type e)
       ('builtin '()) ; do nothing
@@ -712,14 +726,14 @@
 					; outside of an immediate app
 					; but only one closure for each builtin
 
-(define (extract-lambdas program)
+(define (extract-lambdas dls program)
   (define lambdas '())
   (define (add-lambda e)
     (let* ((label (fresh-lambda))
 	   (args (lambda-args e))
-	   (captured (free-vars e))
+	   (captured (free-vars dls e))
 	   (body (extract (lambda-body e)))
-	   (new-lambda (cons label (list captured args body))))
+	   (new-lambda (cons label (list dls captured args body))))
       (set! lambdas (cons new-lambda lambdas))
       `(closure ,label ,captured))) ; todo: should we string->symbol?
 
@@ -753,7 +767,7 @@
 	   (captured '())
 	   (args (builtin-args e))
 	   (body `(,e ,@args))
-	   (new-lambda (cons label (list captured args body)))]
+	   (new-lambda (cons label (list dls captured args body)))]
       (set! lambdas (cons new-lambda lambdas))
       `(closure ,label ,captured)))
   
@@ -842,10 +856,11 @@
     (emit "movq heap_start@GOTPCREL(%rip), %rsi")
     (emit "movq %rax, (%rsi)")))
 
-(define (codegen program)
+(define (codegen program-without-stdlib)
   (set! cur-label 0)
   (set! cur-lambda 0)
-  (let* ([data-layouts (program-data-layouts program)]
+  (let* ([program (append stdlib program-without-stdlib)]
+	 [data-layouts (program-data-layouts program)]
 
 	 [pattern-matched (expand-pattern-matches program)]
 	 [type-annotated (annotate-types pattern-matched)]
@@ -854,13 +869,15 @@
 	 
 	 (strings-res (extract-strings stack-annotated))
 	 (strings (car strings-res))
-	 (lambdas-res (extract-lambdas (cdr strings-res)))
+	 (lambdas-res (extract-lambdas data-layouts (cdr strings-res)))
 	 (lambdas (car lambdas-res))
 	 (xform-prog (cdr lambdas-res)))
 
+					; verify pattern matches are total
+;    (verify-cases data-layouts type-annotated)
+
     (emit "\t.global _start")
     (emit "\t.text")
-					;    (emit ".p2align 4,,15") is this needed?
 
     (for-each codegen-lambda lambdas)
 
@@ -869,7 +886,6 @@
     (initialize-heap)
 
     (emit "movq %rsp, %rbp")            ; set up the base pointer
-    
     (codegen-expr xform-prog (- wordsize) (make-env data-layouts '()))
 
 					; exit syscall
diff --git a/stdlib.scm b/stdlib.scm
new file mode 100644
index 0000000..0cf2917
--- /dev/null
+++ b/stdlib.scm
@@ -0,0 +1,4 @@
+(define stdlib
+  '(
+    (data Bool [false] [true]) ; this relies on false being 0, true being 1
+    ))
diff --git a/tests.scm b/tests.scm
index d2711d7..4e68185 100644
--- a/tests.scm
+++ b/tests.scm
@@ -93,6 +93,13 @@
 	      [z (f 123)])
 	  x)))
 
+(test (singletons '((A [foo] [bar Int]) (B [baz Int] [qux])))
+      '(foo qux))
+
+(test (map (lambda (x) (data-sum-tag '((A [foo] [bar Int]) (B [baz Int] [qux])) x))
+	   '(foo bar baz qux))
+      '(0 1 0 1))
+
 (test-exception
  (expand-pattern-matches '((data A (foo Int Int))
 			   (let ([(foo x) (foo 123 234)])
@@ -106,12 +113,12 @@
 (test-types (substitute '((t1 . (abs t1 t10))) 't1) '(abs t1 t10))
 
 (test-types (typecheck '((let ([bar (lambda (y) y)]
-			       [foo (lambda (x) (foo (bar #t)))])
+			       [foo (lambda (x) (foo (bar true)))])
 			   foo)))
 	    '(abs Bool a))
 
 (test-types (typecheck '((let ([bar (lambda (y) y)]
-			       [foo (lambda (x) (foo (bar #t)))])
+			       [foo (lambda (x) (foo (bar true)))])
 			   bar)))
 	    '(abs a a))
 
@@ -217,8 +224,8 @@
 
 					; passing builtins about
 (test-expr '((lambda (x) ((lambda (a b) (a b 3)) + x)) 3) 6)
-(test-expr '(bool->int ((lambda (x) (x #f)) !)) 1)
-(test-expr '((lambda (f) (f #t)) bool->int) 1)
+(test-expr '(bool->int ((lambda (x) (x false)) !)) 1)
+(test-expr '((lambda (f) (f true)) bool->int) 1)
 (test-prog-stdout '((let () ((lambda (f) (f "foo")) print) 0)) "foo")
 (test-expr '((lambda (f) (f 3 3)) (lambda (x y) (bool->int (= x y)))) 1)
 (test-expr '(bool->int ((lambda (f) (! (f 2 3))) =)) 1)
@@ -312,14 +319,27 @@
 	     (case (bar (foo 42))
 	       [(bar (foo x)) x]))
 	   42)
+
+
+					; mix of singleton and non singleton constructors
+(test-prog '((data A [foo Int] [bar])
+	     (case (foo 42)
+	       [(foo x) x]
+	       [bar 0]))
+	   42)
+
+(test-prog '((data A [foo Int] [bar])
+	     (case bar
+	       [(foo x) 0]
+	       [bar 12]))
+	     12)
 					; todo: make this error for incomplete pattern match 
-(test-prog '((data A [foo Int] [bar Int B])
+(test-exception '((data A [foo Int] [bar Int B])
 		  (data B [baz Int])
 		  (let ([val (bar 42 (baz 12))])
 		    (case val
 		      [(foo 42) 0]
 		      [(bar 32 (baz 12)) 1]
 		      [(bar 42 (baz x)) x]
-		 [(foo x) 2])))
-	   12)
+		      [(foo x) 2]))))
 
diff --git a/typecheck.scm b/typecheck.scm
index f6d7c86..b2b001f 100644
--- a/typecheck.scm
+++ b/typecheck.scm
@@ -1,4 +1,5 @@
 (load "ast.scm")
+(load "stdlib.scm")
 
 (define (abs? t)
   (and (list? t) (eq? (car t) 'abs)))
@@ -258,7 +259,6 @@
       ((res
 	(case (ast-type x)
 	  ('int-literal (make-result '() 'Int))
-	  ('bool-literal (make-result '() 'Bool))
 	  ('string-literal (make-result '() 'String))
 	  ('builtin (make-result '() (builtin-type x)))
 
@@ -318,8 +318,9 @@
   (flat-map data-tors-type-env (program-data-layouts prog)))
 
 					; we typecheck the lambda calculus only (only single arg lambdas)
-(define (typecheck prog)
-  (let ([expanded (expand-pattern-matches prog)])
+(define (typecheck prog-without-stdlib)
+  (let* ([prog (append stdlib prog-without-stdlib)]
+	 [expanded (expand-pattern-matches prog)])
     (cadr (check (program-data-layouts prog)
 		 (init-adts-env expanded)
 		 (normalize (program-body expanded))))))
-- 
2.30.2