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Pluggable instruction sets

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This commit is contained in:
Dane Johnson
2026-02-10 10:58:48 -06:00
parent e4fe2c6bff
commit 4280841719
6 changed files with 226 additions and 188 deletions
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16
scmvm/assembler.scm
View File

@@ -9,24 +9,26 @@
assembler-pos assembler-pos-set! assembler-pos assembler-pos-set!
assembler-buf assembler-buf
assembler-labels assembler-labels
assembler-instruction-set
emit-label emit-label
emit-instruction emit-instruction
emit-literal emit-literal
emit-reference emit-reference
finalize-references assembler-backpatch!
assembler-dump-program)) assembler-dump-program))
(define (make-label) (cons #f '())) (define (make-label) (cons #f '()))
(define-record-type <assembler> (define-record-type <assembler>
(make-assembler pos buf labels) (make-assembler pos buf labels instruction-set)
assembler? assembler?
(pos assembler-pos assembler-pos-set!) (pos assembler-pos assembler-pos-set!)
(buf assembler-buf assembler-buf-set!) (buf assembler-buf assembler-buf-set!)
(labels assembler-labels)) (labels assembler-labels)
(instruction-set assembler-instruction-set))
(define (make-assembler*) (define (make-assembler* instruction-set)
(make-assembler 0 (make-bytevector 1024) (make-hash-table))) (make-assembler 0 (make-bytevector 1024) (make-hash-table) instruction-set))
(define (assembler-buf-grow! asm) (define (assembler-buf-grow! asm)
(let ([buf (make-bytevector (ash (bytevector-length (assembler-buf asm)) -1))]) (let ([buf (make-bytevector (ash (bytevector-length (assembler-buf asm)) -1))])
@@ -59,7 +61,7 @@
(assembler-label-add-value asm name (assembler-pos asm))) (assembler-label-add-value asm name (assembler-pos asm)))
(define (emit-instruction asm inst) (define (emit-instruction asm inst)
(let ([inst-object (assq inst *instruction-set*)]) (let ([inst-object (instruction-lookup (assembler-instruction-set asm) inst)])
(write-byte (instruction-code inst-object) asm) (write-byte (instruction-code inst-object) asm)
(assembler-pos-set! asm (+ (assembler-pos asm) 1)))) (assembler-pos-set! asm (+ (assembler-pos asm) 1))))
@@ -71,7 +73,7 @@
(assembler-label-add-reference asm name (assembler-pos asm)) (assembler-label-add-reference asm name (assembler-pos asm))
(assembler-pos-set! asm (+ (assembler-pos asm) 4))) (assembler-pos-set! asm (+ (assembler-pos asm) 4)))
(define (finalize-references asm) (define (assembler-backpatch! asm)
(define (install-location _name label) (define (install-location _name label)
(for-each (for-each
(cute write-word (car label) asm <>) (cute write-word (car label) asm <>)

2
scmvm/debugger.scm
View File

@@ -56,7 +56,7 @@
(((debugger-breakpoints the-debugger) 'ref) (vm-pc (debugger-vm the-debugger)))) (((debugger-breakpoints the-debugger) 'ref) (vm-pc (debugger-vm the-debugger))))
(debugger-continuation-set! the-debugger k) (debugger-continuation-set! the-debugger k)
(k)))) (k))))
(define vm (make-vm #:debugger debug)) (define vm (make-vm (assembler-instruction-set asm) #:debugger debug))
(vm-load-program! vm prgm) (vm-load-program! vm prgm)
(set! the-debugger (make-debugger vm asm (make-breakpoints asm) #f #f)) (set! the-debugger (make-debugger vm asm (make-breakpoints asm) #f #f))
(debugger-breakpoint-add! the-debugger 1) (debugger-breakpoint-add! the-debugger 1)

45
scmvm/language/assembly.scm
View File

@@ -3,7 +3,7 @@
#:use-module (scmvm assembler) #:use-module (scmvm assembler)
#:use-module (srfi srfi-1) #:use-module (srfi srfi-1)
#:use-module ((scheme base) #:select (write-bytevector)) #:use-module ((scheme base) #:select (write-bytevector))
#:export (assemble assemble-instructions)) #:export (assemble assemble-instructions!))
(define *aliases* (define *aliases*
'((if . branch))) '((if . branch)))
@@ -11,10 +11,10 @@
(define (or-alias inst) (define (or-alias inst)
(or (assq-ref *aliases* inst) inst)) (or (assq-ref *aliases* inst) inst))
(define (lookup-instruction inst) (define (lookup-instruction isa inst)
(define inst-obj (assq (or-alias inst) *instruction-set*)) (define inst-obj (instruction-lookup isa (or-alias inst)))
(or inst-obj (or inst-obj
(error (format #f "could not find instruction ~a" inst)))) (error (format #f "could not find instruction ~a in ISA ~a" inst isa))))
(define label? (negate pair?)) (define label? (negate pair?))
(define (variable? x) (define (variable? x)
@@ -32,28 +32,29 @@
(emit-literal asm v) (emit-literal asm v)
(emit-reference asm v))) (emit-reference asm v)))
(define (assemble-instructions asm inst-seq) (define (assemble-instructions! asm inst-seq)
(when (pair? inst-seq) (when (pair? inst-seq)
(define next-inst (car inst-seq))
(cond (cond
[(label? (car inst-seq)) [(label? next-inst)
(emit-label asm (car inst-seq))] (emit-label asm next-inst)]
[(variable? (car inst-seq)) [(variable? next-inst)
(emit-label asm (second (car inst-seq))) (emit-label asm (second next-inst))
(emit-literal asm (third (car inst-seq)))] (emit-literal asm (third next-inst))]
[(ref? (car inst-seq)) [(ref? next-inst)
(emit-push asm (second (car inst-seq))) (emit-push asm (second next-inst))
(emit-instruction asm '@)] (emit-instruction asm '@)]
[(set!? (car inst-seq)) [(set!? next-inst)
(emit-push asm (second (car inst-seq))) (emit-push asm (second next-inst))
(emit-instruction asm '!)] (emit-instruction asm '!)]
[(push? (car inst-seq)) [(push? next-inst)
(emit-push asm (second (car inst-seq)))] (emit-push asm (second next-inst))]
[else [else
(emit-instruction asm (instruction-name (lookup-instruction (first (car inst-seq)))))]) (emit-instruction asm (instruction-name (lookup-instruction (assembler-instruction-set asm) (first next-inst))))])
(assemble-instructions asm (cdr inst-seq)))) (assemble-instructions! asm (cdr inst-seq))))
(define (assemble instructions port) (define (assemble instructions instruction-set port)
(define asm (make-assembler)) (define asm (make-assembler instruction-set))
(assemble-instructions asm instructions) (assemble-instructions! asm instructions)
(finalize-references asm) (assembler-backpatch! asm)
(assembler-dump-program asm port)) (assembler-dump-program asm port))

11
scmvm/language/scheme.scm
View File

@@ -299,6 +299,7 @@
(primitive-eval `(display (call/cc (lambda (ktail) ,(ir-convert prgm))))) (primitive-eval `(display (call/cc (lambda (ktail) ,(ir-convert prgm)))))
(newline)) (newline))
(ir-interpreter)) (ir-interpreter))
;; Optimization ;; Optimization
(define-syntax-rule (define-cps-type name field ...) (define-syntax-rule (define-cps-type name field ...)
(begin (begin
@@ -349,11 +350,11 @@
[($ $constant val) val] [($ $constant val) val]
[($ $primitive name) `(cps-prim ,name)] [($ $primitive name) `(cps-prim ,name)]
[($ $var name) name] [($ $var name) name]
[($ $abstraction vars body ktail) `(lambda (,@vars ,ktail) ,body)] [($ $abstraction vars body ktail) `(lambda (,@(map unparse-cps vars) ,ktail) ,(unparse-cps body))]
[($ $alternative pred kt kf) `(if ,pred ,kt ,kf)] [($ $alternative pred kt kf) `(if ,(unparse-cps pred) ,kt ,kf)]
[($ $fix vars exps body) `(letrec ,(zip vars exps) ,body)] [($ $fix vars exps body) `(letrec ,(zip (map unparse-cps vars) (map unparse-cps exps)) ,(unparse-cps body))]
[($ $assignment var expr cont) `(set!-then ,var ,expr ,cont)] [($ $assignment var expr cont) `(set!-then ,(unparse-cps var) ,(unparse-cps expr) ,(unparse-cps cont))]
[($ $application fun args ktail) `(,fun ,@args ,ktail)] [($ $application fun args ktail) `(,(unparse-cps fun) ,@(map unparse-cps args) ,ktail)]
[_ (error "Unexpected cps while unparsing" exp)])) [_ (error "Unexpected cps while unparsing" exp)]))
;; Compilation ;; Compilation

314
scmvm/vm.scm
View File

@@ -13,7 +13,9 @@
vm-data-stack vm-ret-stack vm-data-stack vm-ret-stack
vm-debugger vm-debugger-set! vm-debugger vm-debugger-set!
vm-pc vm-pc-set! vm-pc vm-pc-set!
*instruction-set* instruction-name instruction-code)) vm-instruction-set
instruction-lookup instruction-name instruction-code
forth-instruction-set))
;;; Data Structures ;;; Data Structures
(define *stack-size* 512) (define *stack-size* 512)
@@ -95,169 +97,201 @@
(bytevector-s32-ref bv 0 (native-endianness)))) (bytevector-s32-ref bv 0 (native-endianness))))
;;; Instructions ;;; Instructions
(define *instruction-set* (define-syntax define-instruction-set
'((push #x01) (syntax-rules (define-instruction)
(! #x02) [(_ set-name (define-instruction (name opcode) impl ...) ...)
(@ #x03) (define (set-name dispatch)
(+ #x04) (case dispatch
(- #x05) [(lookup)
(and #x06) (lambda (lookup)
(or #x07) (case lookup
(nand #x08) [(name) '(name opcode)] ...
(nor #x09) [else #f]))]
(xor #x0a) [(call)
(= #x0b) (lambda (op)
(> #x0c) (case op
(< #x0d) [(opcode) impl ...] ...))]))]))
(jmp #x0e)
(branch #x0f) (define (instruction-lookup isa name)
(call #x10) ((isa 'lookup) name))
(return #x11)
(>R #x12) (define (instruction-set-call isa op)
(R> #x13) ((isa 'call) op))
(drop #x14)
(nip #x15)
(dup #x16)
(swap #x17)
(rot #x18)
(over #x19)
(not #x1a)
(set! #x1b)
(bye #xff)))
(define instruction-name car) (define instruction-name car)
(define instruction-code cadr) (define instruction-code cadr)
(define (op-lookup code) (define-instruction-set forth-instruction-set
(let ([op (find (lambda (x) (= (instruction-code x) code)) *instruction-set*)]) (define-instruction (push #x01)
(if op (push (*data-stack*) (fetch-word!)))
(car op) (define-instruction (! #x02)
(error (format #f "tried to execute non-existant instruction ~x" code))))) (let ([addr (pop (*data-stack*))]
[v (pop (*data-stack*))])
(define (binop-lookup op) (ram-word-set! addr v)))
(case (op-lookup op) (define-instruction (@ #x03)
[(+) +] (let* ([addr (pop (*data-stack*))]
[(-) -] [v (ram-word-ref addr)])
[(and) logand] (push (*data-stack*) v)))
[(or) logior] (define-instruction (+ #x04)
[(nand) (compose lognot logand)] (let ([v2 (pop (*data-stack*))]
[(nor) (compose lognot logior)] [v1 (pop (*data-stack*))])
[(xor) logxor] (push (*data-stack*) (+ v1 v2))))
[(not) lognot])) (define-instruction (- #x05)
(let ([v2 (pop (*data-stack*))]
(define (relop-lookup op) [v1 (pop (*data-stack*))])
(case (op-lookup op) (push (*data-stack*) (- v1 v2))))
[(>) >] (define-instruction (and #x06)
[(<) <] (let ([v2 (pop (*data-stack*))]
[(=) =])) [v1 (pop (*data-stack*))])
(push (*data-stack*) (logand v1 v2))))
(define-instruction (or #x07)
(let ([v2 (pop (*data-stack*))]
[v1 (pop (*data-stack*))])
(push (*data-stack*) (logior v1 v2))))
(define-instruction (nand #x08)
(let ([v2 (pop (*data-stack*))]
[v1 (pop (*data-stack*))])
(push (*data-stack*) (if (zero? (logand v1 v2)) 1 0))))
(define-instruction (nor #x09)
(let ([v2 (pop (*data-stack*))]
[v1 (pop (*data-stack*))])
(push (*data-stack*) (if (zero? (logior v1 v2)) 1 0))))
(define-instruction (xor #x0a)
(let ([v2 (pop (*data-stack*))]
[v1 (pop (*data-stack*))])
(push (*data-stack*) (logxor v1 v2))))
(define-instruction (= #x0b)
(let ([v2 (pop (*data-stack*))]
[v1 (pop (*data-stack*))])
(if (= v1 v2)
(push (*data-stack*) 1)
(push (*data-stack*) 0))))
(define-instruction (> #x0c)
(let ([v2 (pop (*data-stack*))]
[v1 (pop (*data-stack*))])
(if (> v1 v2)
(push (*data-stack*) 1)
(push (*data-stack*) 0))))
(define-instruction (< #x0d)
(let ([v2 (pop (*data-stack*))]
[v1 (pop (*data-stack*))])
(if (< v1 v2)
(push (*data-stack*) 1)
(push (*data-stack*) 0))))
(define-instruction (jmp #x0e)
(jump! (pop (*data-stack*))))
(define-instruction (branch #x0f)
(let* ([addr (pop (*data-stack*))]
[test (pop (*data-stack*))])
(when (zero? test)
(jump! addr))))
(define-instruction (call #x10)
(let ([addr (pop (*data-stack*))])
(push (*ret-stack*) (vm-pc (*vm*)))
(jump! addr)))
(define-instruction (return #x11)
(jump! (pop (*ret-stack*))))
(define-instruction (>R #x12)
(push (*ret-stack*) (pop (*data-stack*))))
(define-instruction (R> #x13)
(push (*data-stack*) (pop (*ret-stack*))))
(define-instruction (drop #x14)
(pop (*data-stack*)))
(define-instruction (nip #x15)
(let ([v (pop (*data-stack*))])
(pop (*data-stack*))
(push (*data-stack*) v)))
(define-instruction (dup #x16)
(push (*data-stack*) (peek (*data-stack*))))
(define-instruction (swap #x17)
(swap (*data-stack*)))
(define-instruction (rot #x18)
(let* ([a (pop (*data-stack*))]
[b (pop (*data-stack*))]
[c (pop (*data-stack*))])
(push (*data-stack*) a)
(push (*data-stack*) c)
(push (*data-stack*) b)))
(define-instruction (over #x19)
(let* ([a (pop (*data-stack*))]
[b (pop (*data-stack*))])
(push (*data-stack*) b)
(push (*data-stack*) a)
(push (*data-stack*) b)))
(define-instruction (not #x1a)
(let ([a (pop (*data-stack*))])
(push (*data-stack*) (if (zero? a) 1 0))))
(define-instruction (set! #x1b)
;; use let* to induce an order of evaluation
(let* ([idx (pop (*data-stack*))]
[obj (pop (*data-stack*))])
(stack-set! (*data-stack*) idx obj)))
(define-instruction (bye #xff)
(*vm-exit* #t)))
;;; VM
(define-record-type <vm> (define-record-type <vm>
(make-vm data-stack ret-stack memory pc debugger) (make-vm data-stack ret-stack memory pc debugger instruction-set)
vm? vm?
(data-stack vm-data-stack) (data-stack vm-data-stack)
(ret-stack vm-ret-stack) (ret-stack vm-ret-stack)
(memory vm-memory) (memory vm-memory)
(pc vm-pc vm-pc-set!) (pc vm-pc vm-pc-set!)
(debugger vm-debugger vm-debugger-set!)) (debugger vm-debugger vm-debugger-set!)
(instruction-set vm-instruction-set vm-instruction-set-set!))
(define* (make-vm* #:key stack-size memory-size debugger) (define* (make-vm* instruction-set #:key stack-size memory-size debugger)
"Create a fresh VM, with optional stack and memory sizes" "Create a fresh VM, with optional stack and memory sizes"
(define data-stack (if stack-size (make-stack stack-size) (make-stack))) (define data-stack (if stack-size (make-stack stack-size) (make-stack)))
(define ret-stack (if stack-size (make-stack stack-size) (make-stack))) (define ret-stack (if stack-size (make-stack stack-size) (make-stack)))
(define ram (if memory-size (make-ram memory-size) (make-ram))) (define ram (if memory-size (make-ram memory-size) (make-ram)))
(make-vm data-stack ret-stack ram 1 debugger)) (define isa (if instruction-set instruction-set forth-instruction-set))
(make-vm data-stack ret-stack ram 1 debugger isa))
(define *vm* (make-parameter #f))
(define *data-stack* (make-parameter #f))
(define *ret-stack* (make-parameter #f))
(define *vm-exit* (make-parameter #f))
(define (ram-word-ref k)
(vm-memory-ref (*vm*) k))
(define (ram-byte-ref k)
(vm-memory-byte-ref (*vm*) k))
(define (ram-word-set! k v)
(vm-memory-set! (*vm*) k v))
(define (jump! x)
(vm-pc-set! (*vm*) (logand #x2fffffff x)))
(define (fetch-byte!)
(let* ([vm (*vm*)]
[byte (ram-byte-ref (vm-pc vm))])
(vm-pc-set! vm (+ (vm-pc vm) 1))
byte))
(define (fetch-word!)
(let* ([vm (*vm*)]
[word (ram-word-ref (vm-pc vm))])
(vm-pc-set! vm (+ (vm-pc vm) 4))
word))
;;; Execution ;;; Execution
(define (run-vm vm) (define (run-vm vm)
"Begin execution at pc" "Begin execution at pc"
(define data-stack (vm-data-stack vm)) (parameterize ([*vm* vm]
(define ret-stack (vm-ret-stack vm)) [*data-stack* (vm-data-stack vm)]
(define ram-word-ref (cute vm-memory-ref vm <>)) [*ret-stack* (vm-ret-stack vm)]
(define ram-byte-ref (cute vm-memory-byte-ref vm <>)) [*vm-exit* #f])
(define ram-word-set! (cute vm-memory-set! vm <> <>))
(define debugger (vm-debugger vm)) (define debugger (vm-debugger vm))
(define exit? #f) (let lp ()
(define (jump x) (vm-pc-set! vm (logand #x2fffffff x)))
(define (fetch-byte)
(let ([byte (ram-byte-ref (vm-pc vm))])
(vm-pc-set! vm (+ (vm-pc vm) 1))
byte))
(define (fetch-word)
(let ([word (ram-word-ref (vm-pc vm))])
(vm-pc-set! vm (+ (vm-pc vm) 4))
word))
(when debugger (when debugger
(debugger)) (debugger))
(define op (fetch-byte)) (define op (fetch-byte!))
(case (op-lookup op) (instruction-set-call (vm-instruction-set (*vm*)) op)
[(push) (unless (*vm-exit*) (lp)))))
(push data-stack (fetch-word))]
[(!)
(let ([addr (pop data-stack)]
[v (pop data-stack)])
(ram-word-set! addr v))]
[(@)
(let* ([addr (pop data-stack)]
[v (ram-word-ref addr)])
(push data-stack v))]
[(+ - and or nand nor xor)
(let ([v2 (pop data-stack)]
[v1 (pop data-stack)])
(push data-stack ((binop-lookup op) v1 v2)))]
[(= > <)
(let ([v2 (pop data-stack)]
[v1 (pop data-stack)])
(if ((relop-lookup op) v1 v2)
(push data-stack 1)
(push data-stack 0)))]
[(jmp)
(jump (pop data-stack))]
[(branch)
(let ([addr (pop data-stack)])
(when (zero? (pop data-stack))
(jump addr)))]
[(call)
(let ([addr (pop data-stack)])
(push ret-stack (vm-pc vm))
(jump addr))]
[(return)
(jump (pop ret-stack))]
[(>R)
(push ret-stack (pop data-stack))]
[(R>)
(push data-stack (pop ret-stack))]
[(drop)
(pop data-stack)]
[(nip)
(let ([v (pop data-stack)])
(pop data-stack)
(push data-stack v))]
[(dup)
(push data-stack (peek data-stack))]
[(swap)
(swap data-stack)]
[(rot)
(let* ([a (pop data-stack)]
[b (pop data-stack)]
[c (pop data-stack)])
(push data-stack a)
(push data-stack c)
(push data-stack b))]
[(over)
(let* ([a (pop data-stack)]
[b (pop data-stack)])
(push data-stack b)
(push data-stack a)
(push data-stack b))]
[(set!)
;; use let* to induce an order of evaluation
(let* ([idx (pop data-stack)]
[obj (pop data-stack)])
(stack-set! data-stack idx obj))]
[(bye) (set! exit? #t)])
(when (not exit?)
(run-vm vm)))
(define (vm-memory-ref vm k) (define (vm-memory-ref vm k)
(if (< k 1) (if (< k 1)

20
tests.scm
View File

@@ -110,22 +110,22 @@
(define-test-suite "assembly" (define-test-suite "assembly"
(define-test "adder" (define-test "adder"
(define out (open-output-bytevector)) (define out (open-output-bytevector))
(assemble adder-program-assembly out) (assemble adder-program-assembly forth-instruction-set out)
(assert-equal adder-program-bytecode (get-output-bytevector out))) (assert-equal adder-program-bytecode (get-output-bytevector out)))
(define-test "fib" (define-test "fib"
(define out (open-output-bytevector)) (define out (open-output-bytevector))
(assemble fib-program-assembly out) (assemble fib-program-assembly forth-instruction-set out)
(assert-equal fib-program-bytecode (get-output-bytevector out)))) (assert-equal fib-program-bytecode (get-output-bytevector out))))
(define-test-suite "vm" (define-test-suite "vm"
(define-test "adder" (define-test "adder"
(define my-vm (make-vm)) (define my-vm (make-vm forth-instruction-set))
(vm-load-program! my-vm adder-program-bytecode) (vm-load-program! my-vm adder-program-bytecode)
(vm-pc-set! my-vm 5) (vm-pc-set! my-vm 5)
(run-vm my-vm) (run-vm my-vm)
(assert-equal 3 (vm-memory-ref my-vm 1))) (assert-equal 3 (vm-memory-ref my-vm 1)))
(define-test "fib" (define-test "fib"
(define my-vm (make-vm)) (define my-vm (make-vm forth-instruction-set))
(vm-load-program! my-vm fib-program-bytecode) (vm-load-program! my-vm fib-program-bytecode)
(vm-memory-set! my-vm 1 10) (vm-memory-set! my-vm 1 10)
(vm-pc-set! my-vm 5) (vm-pc-set! my-vm 5)
@@ -134,9 +134,9 @@
(define-test-suite "debugger" (define-test-suite "debugger"
(define-test "modify-running-program" (define-test "modify-running-program"
(define fib-program-asm (make-assembler)) (define fib-program-asm (make-assembler forth-instruction-set))
(assemble-instructions fib-program-asm fib-program-assembly) (assemble-instructions! fib-program-asm fib-program-assembly)
(finalize-references fib-program-asm) (assembler-backpatch! fib-program-asm)
(define my-debugger (make-debugger fib-program-asm)) (define my-debugger (make-debugger fib-program-asm))
(define my-vm (debugger-vm my-debugger)) (define my-vm (debugger-vm my-debugger))
(define my-data (vm-data-stack my-vm)) (define my-data (vm-data-stack my-vm))
@@ -150,9 +150,9 @@
(debugger-continue my-debugger) (debugger-continue my-debugger)
(assert-equal 1 (vm-memory-ref my-vm 1))) (assert-equal 1 (vm-memory-ref my-vm 1)))
(define-test "stepping" (define-test "stepping"
(define fib-program-asm (make-assembler)) (define fib-program-asm (make-assembler forth-instruction-set))
(assemble-instructions fib-program-asm fib-program-assembly) (assemble-instructions! fib-program-asm fib-program-assembly)
(finalize-references fib-program-asm) (assembler-backpatch! fib-program-asm)
(define my-debugger (make-debugger fib-program-asm)) (define my-debugger (make-debugger fib-program-asm))
(define my-vm (debugger-vm my-debugger)) (define my-vm (debugger-vm my-debugger))
(vm-memory-set! my-vm 1 10) (vm-memory-set! my-vm 1 10)