From: Luke Lau <luke_lau@icloud.com>
Date: Wed, 14 Aug 2019 13:09:54 +0000 (+0100)
Subject: Can now pass about adts stored on the stack
X-Git-Url: https://git.lukelau.me/?p=scheme.git;a=commitdiff_plain;h=b1fae591d1981a511bd19218a6c85872344915c6

Can now pass about adts stored on the stack
---

diff --git a/abi.md b/abi.md
index c2ff165..0dbbcc4 100644
--- a/abi.md
+++ b/abi.md
@@ -62,3 +62,8 @@ e.g.
 
 * param 0: pointer to the value of `x`
 * param 1: the value of`y`
+
+# inter-function and stack values
+
+ints, bools and closures are passed around within functions in `%rax`.
+adts are passed on the stack, at whatever stack index the code generation was called with.
\ No newline at end of file
diff --git a/codegen.scm b/codegen.scm
index dededbe..9c692e7 100644
--- a/codegen.scm
+++ b/codegen.scm
@@ -31,6 +31,12 @@
 	   (adt-size adt)
 	   (error #f "unknown size" type)))]))
 
+					; returns the size of an expression's result in bytes
+(define (expr-size e)
+  (if (eqv? (ast-type e) 'stack)
+      (cadr e)
+      wordsize))
+
 (define (on-stack? expr)
   (case (ast-type expr)
     ['stack (cadr expr)]
@@ -118,7 +124,6 @@
     (and (eqv? (ast-type expr) 'closure)
 	 (memv name (caddr expr))))
 
-
   ;; (define (emit-scc scc env)
   ;;   ; acc is a pair of the env and list of touchups
   ;;   (define (emit-binding acc binding)
@@ -146,12 +151,31 @@
   ;; 	))
 
   ;;   (fold-left emit-binding (cons env '()) scc))))
-  
-  (let* ([stack-offsets (map (lambda (name x) ; assoc map of binding name to offset
-			       (cons name (- si (* x wordsize))))
-			     (map car bindings)
-			     (range 0 (length bindings)))]
-	 [inner-si (- si (* (length bindings) wordsize))]
+					; assoc map of binding name to size
+  (define stack-sizes
+    (map (lambda (binding) (cons (car binding) (expr-size (cadr binding))))
+	 bindings))
+
+					; assoc map of binding name to offset
+  (define stack-offsets
+					; 2  4  2  8  6
+    (let* ([totals                      ; 2  6  8  16 22
+	    (reverse (fold-left (lambda (acc x)
+				  (if (null? acc)
+				      (list x)
+				      (cons (+ x (car acc)) acc)))
+				'()
+				(map cdr stack-sizes)))]
+					; 0  2  6  8  16
+	   [relative-offsets (map - totals (map cdr stack-sizes))]
+	   [absolute-offsets (map (lambda (x) (- si x)) b)])
+      (map cons (map car stack-sizes) absolute-offsets)))
+  
+  (let* (
+					; the stack index used when codegening binding body and main body
+					; -> stack ->
+					; [stack-offsets | inner-si]
+	 [inner-si (- si (fold-left + 0 (map cdr stack-sizes)))]
 
 	 [get-offset (lambda (n) (cdr (assoc n stack-offsets)))]
 	 
@@ -168,7 +192,8 @@
 		    [scc-env (make-env (env-data-layouts env) scc-binding-offsets)])
 	       (for-each 
 		(lambda (name)
-		  (let ([expr (cadr (assoc name bindings))])
+		  (let* ([expr (cadr (assoc name bindings))]
+			 [size (expr-size expr)])
 		    (emit "## generating ~a with scc-env ~a" name scc-env)
 		    (if (self-captive-closure? name expr)
 					; if self-captive, insert a flag into the environment to let
@@ -180,7 +205,16 @@
 				       (cons (cons name 'self-captive)
 					     (env-bindings scc-env))))
 			(codegen-expr expr inner-si scc-env))
-		    (emit "movq %rax, ~a(%rbp)" (get-offset name))))
+
+		    (if (on-stack? expr)
+			(begin
+			  ; copy over whatevers on the stack
+			  (emit "leaq ~a(%rbp), %rsi" (- inner-si size))
+			  (emit "leaq ~a(%rbp), %rdi" (- (get-offset name) size))
+			  (emit "movq $~a, %rcx" (/ size wordsize))
+			  (emit "rep movsq"))
+			
+			(emit "movq %rax, ~a(%rbp)" (get-offset name)))))
 		comps)
 	       scc-env))
 	   env
@@ -190,11 +224,20 @@
 		(codegen-expr form inner-si inner-env))
 	      body)))
 
-(define (codegen-var name si env)
-  (let ([binding (assoc name (env-bindings env))])
-    (if (not binding)
-	(error #f (format "Variable ~a is not bound" name))
-	(emit "movq ~a(%rbp), %rax" (cdr binding)))))
+(define (codegen-var e si env)
+  (let* ([stack-size (on-stack? e)]
+	 [name (if (on-stack? e) (caddr e) e)]
+	 [stack-offset (cdr (assoc name (env-bindings env)))])
+    (when (not stack-offset)
+      (error #f (format "Variable ~a is not bound" name)))
+
+    (if (on-stack? e)
+	(begin
+	  (emit "leaq ~a(%rbp), %rsi" (- stack-offset stack-size))
+	  (emit "leaq ~a(%rbp), %rdi" (- si stack-size))
+	  (emit "movq $~a, %rcx" (/ stack-size wordsize))
+	  (emit "rep movsq"))
+	(emit "movq ~a(%rbp), %rax" stack-offset))))
 
 (define cur-lambda 0)
 (define (fresh-lambda)
@@ -395,9 +438,9 @@
 	   [index (caddr info)]
 	   [type (car info)]
 	   [sum (cadr info)])
-      (when (not (stack-expr? res))
-	(error #f "codegened something that wasn't a stack expression"))
-					;TODO handle stack types
+      (when (not (on-stack? (cadr e)))
+	(error #f "trying to destruct something that isn't a stack expression"))
+      (emit "# deconstructing")
       (emit "movq ~a(%rbp), %rax"
 	    (- si (data-product-offset (env-data-layouts env) type sum index)))))				      
 
@@ -419,7 +462,7 @@
 		    [stack-offset (- si (data-product-offset (env-data-layouts env)
 							     type sum
 							     i))])
-		(if (stack-expr? res)
+		(if (on-stack? res)
 		    (error #f "todo: handle stack-exprs in stack exprs")
 		    (emit "movq %rax, ~a(%rbp)" stack-offset))))])
 
@@ -435,9 +478,6 @@
 	(codegen-constructor tor)
 	(codegen-destructor tor))))
 
-(define stack-expr? number?)
-
-					; returns a number if result was stored on stack 
 (define (codegen-expr e si env)
   (emit "# ~a" e)
   (case (ast-type e)
@@ -475,23 +515,25 @@
     ('static-string (emit "movq ~a@GOTPCREL(%rip), %rax"
 			  (cadr e)))
 
-    ('stack (codegen-expr (caddr e) si env))
+    ('stack (case (ast-type (caddr e))
+	      ['var (codegen-var e si env)]
+	      [else (codegen-expr (caddr e) si env)]))
 
     (else (error #f "don't know how to codegen this"))))
 
 					; takes in a expr annotated with types and returns a type-less AST
 					; with stack values wrapped
-(define (annotate-stack-values data-layout ann-e)
+(define (annotate-stack-values data-layouts ann-e)
   (define (stack-type? type)
-    (assoc type data-layout))
+    (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)
-	`(stack ,type ,(ast-traverse strip e))
+	`(stack ,(type-size data-layouts type) ,(ast-traverse strip e))
 	(ast-traverse (lambda (x)
-			(annotate-stack-values data-layout x))
+			(annotate-stack-values data-layouts x))
 		      e))))
 
 (define (free-vars prog)
diff --git a/tests.scm b/tests.scm
index ecee99e..cdd60bd 100644
--- a/tests.scm
+++ b/tests.scm
@@ -264,8 +264,14 @@
 (test-prog '((data A [foo Int])
 	     (let ([x (foo 42)])
 	       (let ([(foo y) x])
-		 (+ 1 y))))
-	   43)
+		 (+ 2 y))))
+	   44)
+
+(test-prog '((data A [foo Bool Int Int])
+	     (let ([x (foo (= 2 1) 123 45)]
+		   [(foo a b c) x])
+	       (+ b c)))
+	   (+ 123 45))
 
 (test-prog '((data A [foo Int])
 	     (data B [bar A])