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janet/vm.c

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#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "vm.h"
#include "value.h"
#include "ds.h"
static const char OOM[] = "Out of memory";
static const char NO_UPVALUE[] = "No upvalue";
static const char EXPECTED_FUNCTION[] = "Expected function";
static const char VMS_EXPECTED_NUMBER_ROP[] = "Expected right operand to be number";
static const char VMS_EXPECTED_NUMBER_LOP[] = "Expected left operand to be number";
/* The stack frame data */
typedef struct StackFrame StackFrame;
struct StackFrame {
Value callee;
uint16_t size;
uint16_t prevSize;
uint16_t ret;
FuncEnv * env;
uint16_t * pc;
};
/* The size of a StackFrame in units of Values. */
static size_t FRAME_SIZE() {
return ((sizeof(StackFrame) + sizeof(Value) - 1) / sizeof(Value));
}
/* Get the stack frame pointer for a thread */
static StackFrame * ThreadFrame(Array * thread) {
return (StackFrame *)(thread->data + thread->count - FRAME_SIZE());
}
/* The metadata header associated with an allocated block of memory */
#define GCHeader(mem) ((GCMemoryHeader *)(mem) - 1)
/* Memory header struct. Node of a linked list of memory blocks. */
typedef struct GCMemoryHeader GCMemoryHeader;
struct GCMemoryHeader {
GCMemoryHeader * next;
uint32_t color;
};
/* Forward declaration */
static void VMMark(VM * vm, Value * x);
/* Helper to mark function environments */
static void VMMarkFuncEnv(VM * vm, FuncEnv * env) {
if (GCHeader(env)->color != vm->black) {
Value temp;
GCHeader(env)->color = vm->black;
if (env->thread) {
temp.type = TYPE_THREAD;
temp.data.array = env->thread;
VMMark(vm, &temp);
} else {
uint32_t count = env->stackOffset;
uint32_t i;
GCHeader(env->values)->color = vm->black;
for (i = 0; i < count; ++i) {
VMMark(vm, env->values + i);
}
}
}
}
/* Mark allocated memory associated with a value. This is
* the main function for doing garbage collection. */
static void VMMark(VM * vm, Value * x) {
switch (x->type) {
case TYPE_NIL:
case TYPE_BOOLEAN:
case TYPE_NUMBER:
case TYPE_CFUNCTION:
break;
case TYPE_STRING:
case TYPE_SYMBOL:
GCHeader(VStringRaw(x->data.string))->color = vm->black;
break;
case TYPE_BYTEBUFFER:
GCHeader(x->data.buffer)->color = vm->black;
GCHeader(x->data.buffer->data)->color = vm->black;
break;
case TYPE_ARRAY:
case TYPE_FORM:
if (GCHeader(x->data.array)->color != vm->black) {
uint32_t i, count;
count = x->data.array->count;
GCHeader(x->data.array)->color = vm->black;
GCHeader(x->data.array->data)->color = vm->black;
for (i = 0; i < count; ++i)
VMMark(vm, x->data.array->data + i);
}
break;
case TYPE_THREAD:
if (GCHeader(x->data.array)->color != vm->black) {
uint32_t i;
Array * thread = x->data.array;
StackFrame * frame = (StackFrame *)thread->data;
StackFrame * end = (StackFrame *)(thread->data + thread->count - FRAME_SIZE());
GCHeader(thread)->color = vm->black;
GCHeader(thread->data)->color = vm->black;
while (frame <= end) {
Value * stack = (Value *)frame + FRAME_SIZE();
VMMark(vm, &frame->callee);
if (frame->env)
VMMarkFuncEnv(vm, frame->env);
for (i = 0; i < frame->size; ++i) {
VMMark(vm, stack + i);
}
frame = (StackFrame *)(stack + frame->size);
}
}
break;
case TYPE_FUNCTION:
if (GCHeader(x->data.func)->color != vm->black) {
Func * f = x->data.func;
GCHeader(f)->color = vm->black;
VMMarkFuncEnv(vm, f->env);
{
Value temp;
temp.type = TYPE_FUNCDEF;
temp.data.funcdef = x->data.funcdef;
VMMark(vm, &temp);
if (f->parent) {
temp.type = TYPE_FUNCTION;
temp.data.func = f->parent;
VMMark(vm, &temp);
}
}
}
break;
case TYPE_DICTIONARY:
if (GCHeader(x->data.dict)->color != vm->black) {
DictionaryIterator iter;
DictBucket * bucket;
GCHeader(x->data.dict)->color = vm->black;
GCHeader(x->data.dict->buckets)->color = vm->black;
DictIterate(x->data.dict, &iter);
while (DictIterateNext(&iter, &bucket)) {
GCHeader(bucket)->color = vm->black;
VMMark(vm, &bucket->key);
VMMark(vm, &bucket->value);
}
}
break;
case TYPE_FUNCDEF:
if (GCHeader(x->data.funcdef)->color != vm->black) {
GCHeader(x->data.funcdef->byteCode)->color = vm->black;
uint32_t count, i;
count = x->data.funcdef->literalsLen;
if (x->data.funcdef->literals) {
GCHeader(x->data.funcdef->literals)->color = vm->black;
for (i = 0; i < count; ++i)
VMMark(vm, x->data.funcdef->literals + i);
}
}
break;
case TYPE_FUNCENV:
VMMarkFuncEnv(vm, x->data.funcenv);
break;
}
}
/* Iterate over all allocated memory, and free memory that is not
* marked as reachable. Flip the gc color flag for next sweep. */
static void VMSweep(VM * vm) {
GCMemoryHeader * previous = NULL;
GCMemoryHeader * current = vm->blocks;
while (current) {
if (current->color != vm->black) {
if (previous) {
previous->next = current->next;
} else {
vm->blocks = current->next;
}
free(current);
} else {
previous = current;
}
current = current->next;
}
/* Rotate flag */
vm->black = !vm->black;
}
/* Prepare a memory block */
static void * VMAllocPrepare(VM * vm, char * rawBlock, uint32_t size) {
GCMemoryHeader * mdata;
if (rawBlock == NULL) {
VMCrash(vm, OOM);
}
vm->nextCollection += size;
mdata = (GCMemoryHeader *) rawBlock;
mdata->next = vm->blocks;
vm->blocks = mdata;
mdata->color = !vm->black;
return rawBlock + sizeof(GCMemoryHeader);
}
/* Allocate some memory that is tracked for garbage collection */
void * VMAlloc(VM * vm, uint32_t size) {
uint32_t totalSize = size + sizeof(GCMemoryHeader);
return VMAllocPrepare(vm, malloc(totalSize), totalSize);
}
/* Allocate some zeroed memory that is tracked for garbage collection */
void * VMZalloc(VM * vm, uint32_t size) {
uint32_t totalSize = size + sizeof(GCMemoryHeader);
return VMAllocPrepare(vm, calloc(1, totalSize), totalSize);
}
/* Run garbage collection */
void VMCollect(VM * vm) {
if (vm->lock > 0) return;
Value thread;
thread.type = TYPE_THREAD;
thread.data.array = vm->thread;
VMMark(vm, &thread);
VMMark(vm, &vm->tempRoot);
VMSweep(vm);
vm->nextCollection = 0;
}
/* Run garbage collection if needed */
void VMMaybeCollect(VM * vm) {
if (vm->nextCollection >= vm->memoryInterval) {
VMCollect(vm);
}
}
/* Push a stack frame onto a thread */
static void VMThreadPush(VM * vm, Array * thread, Value callee, uint32_t size) {
uint16_t oldSize;
uint32_t nextCount, i;
StackFrame * frame;
if (thread->count) {
frame = ThreadFrame(thread);
oldSize = frame->size;
} else {
oldSize = 0;
}
nextCount = thread->count + oldSize + FRAME_SIZE();
ArrayEnsure(vm, thread, nextCount + size);
thread->count = nextCount;
/* Ensure values start out as nil so as to not confuse
* the garabage collector */
for (i = nextCount; i < nextCount + size; ++i)
thread->data[i].type = TYPE_NIL;
frame = ThreadFrame(thread);
/* Set up the new stack frame */
frame->prevSize = oldSize;
frame->size = size;
frame->env = NULL;
frame->callee = callee;
vm->base = thread->data + thread->count;
}
/* Copy the current function stack to the current closure
environment */
static void VMThreadSplitStack(VM * vm, Array * thread) {
StackFrame * frame = ThreadFrame(thread);
FuncEnv * env = frame->env;
/* Check for closures */
if (env) {
uint32_t size = frame->size;
env->thread = NULL;
env->stackOffset = size;
env->values = VMAlloc(vm, sizeof(Value) * size);
memcpy(env->values, thread->data + thread->count, size * sizeof(Value));
}
}
/* Pop the top-most stack frame from stack */
static void VMThreadPop(VM * vm, Array * thread) {
StackFrame * frame = ThreadFrame(thread);
uint32_t delta = FRAME_SIZE() + frame->prevSize;
if (thread->count) {
VMThreadSplitStack(vm, thread);
} else {
VMError(vm, "Nothing to pop from stack.");
}
thread->count -= delta;
vm->base -= delta;
}
/* Get an upvalue */
static Value * GetUpValue(VM * vm, Func * fn, uint16_t level, uint16_t index) {
FuncEnv * env;
Value * stack;
if (!level) {
return vm->base + index;
}
while (fn && --level)
fn = fn->parent;
VMAssert(vm, fn, NO_UPVALUE);
env = fn->env;
if (env->thread)
stack = env->thread->data + env->stackOffset;
else
stack = env->values;
return stack + index;
}
/* Get a constant */
static Value LoadConstant(VM * vm, Func * fn, uint16_t index) {
if (index > fn->def->literalsLen) {
VMError(vm, NO_UPVALUE);
}
return fn->def->literals[index];
}
/* Boolean truth definition */
static int truthy(Value v) {
return v.type != TYPE_NIL && !(v.type == TYPE_BOOLEAN && !v.data.boolean);
}
/* Return from the vm */
static void VMReturn(VM * vm, Value ret) {
Array * thread = vm->thread;
StackFrame * frame = ThreadFrame(thread);
VMThreadPop(vm, thread);
if (thread->count == 0) {
VMExit(vm, ret);
}
frame = ThreadFrame(thread);
vm->pc = frame->pc;
vm->base[frame->ret] = ret;
}
/* Implementation of the opcode for function calls */
static void VMCallOp(VM * vm) {
Array * thread = vm->thread;
StackFrame * frame = ThreadFrame(thread);
Value callee = vm->base[vm->pc[1]];
uint32_t arity = vm->pc[3];
uint32_t oldCount = thread->count;
uint32_t i;
Value * oldBase;
frame->pc = vm->pc + 4 + arity;
frame->ret = vm->pc[2];
if (callee.type == TYPE_FUNCTION) {
Func * fn = callee.data.func;
VMThreadPush(vm, thread, callee, fn->def->locals);
} else if (callee.type == TYPE_CFUNCTION) {
VMThreadPush(vm, thread, callee, arity);
} else {
VMError(vm, EXPECTED_FUNCTION);
}
oldBase = thread->data + oldCount;
if (callee.type == TYPE_CFUNCTION) {
for (i = 0; i < arity; ++i)
vm->base[i] = oldBase[vm->pc[4 + i]];
++vm->lock;
VMReturn(vm, callee.data.cfunction(vm));
--vm->lock;
} else {
Func * f = callee.data.func;
uint32_t locals = f->def->locals;
for (i = 0; i < arity; ++i)
vm->base[i] = oldBase[vm->pc[4 + i]];
for (; i < locals; ++i)
vm->base[i].type = TYPE_NIL;
vm->pc = f->def->byteCode;
}
VMMaybeCollect(vm);
}
/* Implementation of the opcode for tail calls */
static void VMTailCallOp(VM * vm) {
Array * thread = vm->thread;
StackFrame * frame = ThreadFrame(thread);
Value callee = vm->base[vm->pc[1]];
uint32_t arity = vm->pc[2];
uint16_t newFrameSize, currentFrameSize;
uint32_t i;
/* Check for closures */
VMThreadSplitStack(vm, thread);
if (callee.type == TYPE_CFUNCTION) {
newFrameSize = arity;
} else if (callee.type == TYPE_FUNCTION) {
Func * f = callee.data.func;
newFrameSize = f->def->locals;
} else {
VMError(vm, EXPECTED_FUNCTION);
}
/* Ensure stack has enough space for copies of arguments */
currentFrameSize = frame->size;
ArrayEnsure(vm, thread, thread->count + currentFrameSize + arity);
frame = ThreadFrame(thread);
vm->base = thread->data + thread->count;
/* Copy the arguments into the extra space */
for (i = 0; i < arity; ++i) {
vm->base[currentFrameSize + i] = vm->base[vm->pc[3 + i]];
}
/* Copy the end of the stack to the parameter position */
memcpy(vm->base, vm->base + currentFrameSize, arity * sizeof(Value));
/* nil the non argument part of the stack for gc */
for (i = arity; i < newFrameSize; ++i) {
vm->base[i].type = TYPE_NIL;
}
/* Update the stack frame */
frame->size = newFrameSize;
frame->callee = callee;
frame->env = NULL;
if (callee.type == TYPE_CFUNCTION) {
++vm->lock;
VMReturn(vm, callee.data.cfunction(vm));
--vm->lock;
} else {
Func * f = callee.data.func;
vm->pc = f->def->byteCode;
}
VMMaybeCollect(vm);
}
/* Instantiate a closure */
static Value VMMakeClosure(VM * vm, uint16_t literal) {
Array * thread = vm->thread;
StackFrame * frame = ThreadFrame(thread);
if (frame->callee.type != TYPE_FUNCTION) {
VMError(vm, EXPECTED_FUNCTION);
} else {
Value constant, ret;
Func * fn, * current;
FuncEnv * env = frame->env;
if (!env) {
env = VMAlloc(vm, sizeof(FuncEnv));
env->thread = thread;
env->stackOffset = thread->count;
env->values = NULL;
frame->env = env;
}
current = frame->callee.data.func;
constant = LoadConstant(vm, current, literal);
if (constant.type != TYPE_FUNCDEF) {
VMError(vm, EXPECTED_FUNCTION);
}
fn = VMAlloc(vm, sizeof(Func));
fn->def = constant.data.funcdef;
fn->parent = current;
fn->env = env;
ret.type = TYPE_FUNCTION;
ret.data.func = fn;
return ret;
}
}
/* Start running the VM */
int VMStart(VM * vm) {
/* Set jmp_buf to jump back to for return. */
{
int n;
if ((n = setjmp(vm->jump))) {
vm->lock = 0;
/* Good return */
if (n == 1) {
return 0;
} else {
/* Error or crash. Handling TODO. */
return n;
}
}
}
for (;;) {
uint16_t opcode = *vm->pc;
switch (opcode) {
Value temp, v1, v2;
#define DO_BINARY_MATH(op) \
v1 = vm->base[vm->pc[2]]; \
v2 = vm->base[vm->pc[3]]; \
VMAssert(vm, v1.type == TYPE_NUMBER, VMS_EXPECTED_NUMBER_LOP); \
VMAssert(vm, v2.type == TYPE_NUMBER, VMS_EXPECTED_NUMBER_ROP); \
temp.type = TYPE_NUMBER; \
temp.data.number = v1.data.number op v2.data.number; \
vm->base[vm->pc[1]] = temp; \
vm->pc += 4; \
break;
case VM_OP_ADD: /* Addition */
DO_BINARY_MATH(+)
case VM_OP_SUB: /* Subtraction */
DO_BINARY_MATH(-)
case VM_OP_MUL: /* Multiplication */
DO_BINARY_MATH(*)
case VM_OP_DIV: /* Division */
DO_BINARY_MATH(/)
#undef DO_BINARY_MATH
case VM_OP_NOT: /* Boolean unary (Boolean not) */
temp.type = TYPE_BOOLEAN;
temp.data.boolean = !truthy(vm->base[vm->pc[2]]);
vm->base[vm->pc[1]] = temp;
vm->pc += 3;
break;
case VM_OP_LD0: /* Load 0 */
temp.type = TYPE_NUMBER;
temp.data.number = 0;
vm->base[vm->pc[1]] = temp;
vm->pc += 2;
break;
case VM_OP_LD1: /* Load 1 */
temp.type = TYPE_NUMBER;
temp.data.number = 1;
vm->base[vm->pc[1]] = temp;
vm->pc += 2;
break;
case VM_OP_FLS: /* Load False */
temp.type = TYPE_BOOLEAN;
temp.data.boolean = 0;
vm->base[vm->pc[1]] = temp;
vm->pc += 2;
break;
case VM_OP_TRU: /* Load True */
temp.type = TYPE_BOOLEAN;
temp.data.boolean = 1;
vm->base[vm->pc[1]] = temp;
vm->pc += 2;
break;
case VM_OP_NIL: /* Load Nil */
temp.type = TYPE_NIL;
vm->base[vm->pc[1]] = temp;
vm->pc += 2;
break;
case VM_OP_I16: /* Load Small Integer */
temp.type = TYPE_NUMBER;
temp.data.number = ((int16_t *)(vm->pc))[2];
vm->base[vm->pc[1]] = temp;
vm->pc += 3;
break;
case VM_OP_UPV: /* Load Up Value */
temp = ThreadFrame(vm->thread)->callee;
VMAssert(vm, temp.type == TYPE_FUNCTION, EXPECTED_FUNCTION);
vm->base[vm->pc[1]] = *GetUpValue(vm, temp.data.func, vm->pc[2], vm->pc[3]);
vm->pc += 4;
break;
case VM_OP_JIF: /* Jump If */
if (truthy(vm->base[vm->pc[1]])) {
vm->pc += 4;
} else {
vm->pc += *((int32_t *)(vm->pc + 2));
}
break;
case VM_OP_JMP: /* Jump */
vm->pc += *((int32_t *)(vm->pc + 1));
break;
case VM_OP_CAL: /* Call */
VMCallOp(vm);
break;
case VM_OP_RET: /* Return */
VMReturn(vm, vm->base[vm->pc[1]]);
break;
case VM_OP_SUV: /* Set Up Value */
temp = ThreadFrame(vm->thread)->callee;
VMAssert(vm, temp.type == TYPE_FUNCTION, EXPECTED_FUNCTION);
*GetUpValue(vm, temp.data.func, vm->pc[2], vm->pc[3]) = vm->base[vm->pc[1]];
vm->pc += 4;
break;
case VM_OP_CST: /* Load constant value */
temp = ThreadFrame(vm->thread)->callee;
VMAssert(vm, temp.type == TYPE_FUNCTION, EXPECTED_FUNCTION);
vm->base[vm->pc[1]] = LoadConstant(vm, temp.data.func, vm->pc[2]);
vm->pc += 3;
break;
case VM_OP_I32: /* Load 32 bit integer */
temp.type = TYPE_NUMBER;
temp.data.number = *((int32_t *)(vm->pc + 2));
vm->base[vm->pc[1]] = temp;
vm->pc += 4;
break;
case VM_OP_F64: /* Load 64 bit float */
temp.type = TYPE_NUMBER;
temp.data.number = (Number) *((double *)(vm->pc + 2));
vm->base[vm->pc[1]] = temp;
vm->pc += 6;
break;
case VM_OP_MOV: /* Move Values */
vm->base[vm->pc[1]] = vm->base[vm->pc[2]];
vm->pc += 3;
break;
case VM_OP_CLN: /* Create closure from constant FuncDef */
vm->base[vm->pc[1]] = VMMakeClosure(vm, vm->pc[2]);
vm->pc += 3;
break;
case VM_OP_EQL: /* Equality */
temp.type = TYPE_BOOLEAN;
temp.data.boolean = ValueEqual(vm->base[vm->pc[2]], vm->base[vm->pc[3]]);
vm->base[vm->pc[1]] = temp;
vm->pc += 4;
break;
case VM_OP_LTN: /* Less Than */
temp.type = TYPE_BOOLEAN;
temp.data.boolean = (ValueCompare(vm->base[vm->pc[2]], vm->base[vm->pc[3]]) == -1);
vm->base[vm->pc[1]] = temp;
vm->pc += 4;
break;
case VM_OP_LTE: /* Less Than or Equal to */
temp.type = TYPE_BOOLEAN;
temp.data.boolean = (ValueEqual(vm->base[vm->pc[2]], vm->base[vm->pc[3]]) != 1);
vm->base[vm->pc[1]] = temp;
vm->pc += 4;
break;
case VM_OP_ARR: /* Array literal */
{
uint32_t i;
uint32_t arrayLen = vm->pc[2];
Array * array = ArrayNew(vm, arrayLen);
array->count = arrayLen;
for (i = 0; i < arrayLen; ++i)
array->data[i] = vm->base[vm->pc[3 + i]];
temp.type = TYPE_ARRAY;
temp.data.array = array;
vm->base[vm->pc[1]] = temp;
vm->pc += 3 + arrayLen;
VMMaybeCollect(vm);
}
break;
case VM_OP_DIC: /* Dictionary literal */
{
uint32_t i = 3;
uint32_t kvs = vm->pc[2];
Dictionary * dict = DictNew(vm, kvs);
kvs = kvs + 3;
while (i < kvs) {
v1 = vm->base[vm->pc[i++]];
v2 = vm->base[vm->pc[i++]];
DictPut(vm, dict, v1, v2);
}
temp.type = TYPE_DICTIONARY;
temp.data.dict = dict;
vm->base[vm->pc[1]] = temp;
vm->pc += kvs;
VMMaybeCollect(vm);
}
break;
case VM_OP_TCL: /* Tail call */
VMTailCallOp(vm);
break;
/* Macro for generating some math operators */
#define DO_MULTI_MATH(op, start) { \
uint16_t count = vm->pc[2]; \
uint16_t i; \
Number accum = start; \
for (i = 0; i < count; ++i) { \
v1 = vm->base[vm->pc[3 + i]]; \
VMAssert(vm, v1.type == TYPE_NUMBER, "Expected number"); \
accum = accum op v1.data.number; \
} \
temp.type = TYPE_NUMBER; \
temp.data.number = accum; \
vm->base[vm->pc[1]] = temp; \
vm->pc += 3 + count; \
break; \
}
/* Vectorized math */
case VM_OP_ADM:
DO_MULTI_MATH(+, 0)
case VM_OP_SBM:
DO_MULTI_MATH(-, 0)
case VM_OP_MUM:
DO_MULTI_MATH(*, 1)
case VM_OP_DVM:
DO_MULTI_MATH(/, 1)
#undef DO_MULTI_MATH
case VM_OP_RTN: /* Return nil */
temp.type = TYPE_NIL;
VMReturn(vm, temp);
break;
case VM_OP_GET:
break;
default:
VMError(vm, "Unknown opcode");
break;
}
}
}
/* Get an argument from the stack */
Value VMGetArg(VM * vm, uint16_t index) {
uint16_t frameSize = ThreadFrame(vm->thread)->size;
VMAssert(vm, frameSize > index, "Cannot get arg out of stack bounds");
return vm->base[index];
}
/* Put a value on the stack */
void VMSetArg(VM * vm, uint16_t index, Value x) {
uint16_t frameSize = ThreadFrame(vm->thread)->size;
VMAssert(vm, frameSize > index, "Cannot set arg out of stack bounds");
vm->base[index] = x;
}
/* Get the size of the VMStack */
uint16_t VMCountArgs(VM * vm) {
return ThreadFrame(vm->thread)->size;
}
/* Initialize the VM */
void VMInit(VM * vm) {
vm->tempRoot.type = TYPE_NIL;
vm->base = NULL;
vm->pc = NULL;
vm->error = NULL;
/* Garbage collection */
vm->blocks = NULL;
vm->nextCollection = 0;
vm->memoryInterval = 1024 * 256;
vm->black = 0;
vm->lock = 0;
/* Create new thread */
vm->thread = ArrayNew(vm, 32);
}
/* Load a function into the VM. The function will be called with
* no arguments when run */
void VMLoad(VM * vm, Func * func) {
Value callee;
callee.type = TYPE_FUNCTION;
callee.data.func = func;
vm->thread = ArrayNew(vm, 32);
VMThreadPush(vm, vm->thread, callee, func->def->locals);
vm->pc = func->def->byteCode;
}
/* Clear all memory associated with the VM */
void VMDeinit(VM * vm) {
GCMemoryHeader * current = vm->blocks;
while (current) {
GCMemoryHeader * next = current->next;
free(current);
current = next;
}
vm->blocks = NULL;
}
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