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janet/core/vm.c

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C
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/*
* Copyright (c) 2017 Calvin Rose
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <dst/dst.h>
#include "opcodes.h"
#include "symcache.h"
#include "gc.h"
/* VM State */
DstFiber *dst_vm_fiber = NULL;
/* Helper to ensure proper fiber is activated after returning */
static int dst_update_fiber() {
if (dst_vm_fiber->frame == 0) {
dst_vm_fiber->status = DST_FIBER_DEAD;
}
while (dst_vm_fiber->status == DST_FIBER_DEAD ||
dst_vm_fiber->status == DST_FIBER_ERROR) {
if (NULL != dst_vm_fiber->parent) {
dst_vm_fiber = dst_vm_fiber->parent;
if (dst_vm_fiber->status == DST_FIBER_ALIVE) {
/* If the parent thread is still alive,
we are inside a cfunction */
return 1;
}
} else {
/* The root thread has termiated */
return 1;
}
}
dst_vm_fiber->status = DST_FIBER_ALIVE;
return 0;
}
/* Start running the VM from where it left off. */
static int dst_continue(DstValue *returnreg) {
/* VM state */
DstValue *stack;
uint32_t *pc;
DstFunction *func;
DstValue retreg;
/* Eventually use computed gotos for more effient vm loop. */
#define vm_next() continue
#define vm_checkgc_next() dst_maybe_collect(); continue
/* Used to extract bits from the opcode that correspond to arguments.
* Pulls out unsigned integers */
#define oparg(shift, mask) (((*pc) >> ((shift) << 3)) & (mask))
#define vm_throw(e) do { retreg = dst_cstringv((e)); goto vm_error; } while (0)
#define vm_assert(cond, e) do {if (!(cond)) vm_throw((e)); } while (0)
#define vm_binop_integer(op) \
stack[oparg(1, 0xFF)] = dst_wrap_integer(\
dst_unwrap_integer(stack[oparg(2, 0xFF)]) op dst_unwrap_integer(stack[oparg(3, 0xFF)])\
);\
pc++;\
vm_next();
#define vm_binop_real(op)\
stack[oparg(1, 0xFF)] = dst_wrap_real(\
dst_unwrap_real(stack[oparg(2, 0xFF)]) op dst_unwrap_real(stack[oparg(3, 0xFF)])\
);\
pc++;\
vm_next();
#define vm_binop_immediate(op)\
stack[oparg(1, 0xFF)] = dst_wrap_integer(\
dst_unwrap_integer(stack[oparg(2, 0xFF)]) op (*((int32_t *)pc) >> 24)\
);\
pc++;\
vm_next();
#define vm_binop(op)\
{\
DstValue op1 = stack[oparg(2, 0xFF)];\
DstValue op2 = stack[oparg(3, 0xFF)];\
vm_assert(dst_checktype(op1, DST_INTEGER) || dst_checktype(op1, DST_REAL), "expected number");\
vm_assert(dst_checktype(op2, DST_INTEGER) || dst_checktype(op2, DST_REAL), "expected number");\
stack[oparg(1, 0xFF)] = dst_checktype(op1, DST_INTEGER)\
? (dst_checktype(op2, DST_INTEGER)\
? dst_wrap_integer(dst_unwrap_integer(op1) op dst_unwrap_integer(op2))\
: dst_wrap_real((double)dst_unwrap_integer(op1) op dst_unwrap_real(op2)))\
: (dst_checktype(op2, DST_INTEGER)\
? dst_wrap_real(dst_unwrap_real(op1) op (double)dst_unwrap_integer(op2))\
: dst_wrap_real(dst_unwrap_real(op1) op dst_unwrap_real(op2)));\
pc++;\
vm_next();\
}
#define vm_init_fiber_state() \
dst_vm_fiber->status = DST_FIBER_ALIVE;\
stack = dst_vm_fiber->data + dst_vm_fiber->frame;\
pc = dst_stack_frame(stack)->pc;\
func = dst_stack_frame(stack)->func;
vm_init_fiber_state();
/* Main interpreter loop. It is large, but it is
* is maintainable. Adding new opcodes is mostly just adding newcases
* to this loop, adding the opcode to opcodes.h, and adding it to the assembler.
* Some opcodes, especially ones that do arithmetic, are almost entirely
* templated by the above macros. */
for (;;) {
switch (*pc & 0xFF) {
default:
vm_throw("unknown opcode");
case DOP_NOOP:
pc++;
vm_next();
case DOP_ERROR:
retreg = stack[oparg(1, 0xFF)];
goto vm_error;
case DOP_TYPECHECK:
vm_assert((1 << dst_type(stack[oparg(1, 0xFF)])) & oparg(2, 0xFFFF),
"typecheck failed");
pc++;
vm_next();
case DOP_RETURN:
retreg = stack[oparg(1, 0xFFFFFF)];
goto vm_return;
case DOP_RETURN_NIL:
retreg = dst_wrap_nil();
goto vm_return;
case DOP_ADD_INTEGER:
vm_binop_integer(+);
case DOP_ADD_IMMEDIATE:
vm_binop_immediate(+);
case DOP_ADD_REAL:
vm_binop_real(+);
case DOP_ADD:
vm_binop(+);
case DOP_SUBTRACT_INTEGER:
vm_binop_integer(-);
case DOP_SUBTRACT_REAL:
vm_binop_real(-);
case DOP_SUBTRACT:
vm_binop(-);
case DOP_MULTIPLY_INTEGER:
vm_binop_integer(*);
case DOP_MULTIPLY_IMMEDIATE:
vm_binop_immediate(*);
case DOP_MULTIPLY_REAL:
vm_binop_real(*);
case DOP_MULTIPLY:
vm_binop(*);
case DOP_DIVIDE_INTEGER:
vm_assert(dst_unwrap_integer(stack[oparg(3, 0xFF)]) != 0, "integer divide error");
vm_assert(!(dst_unwrap_integer(stack[oparg(3, 0xFF)]) == -1 &&
dst_unwrap_integer(stack[oparg(2, 0xFF)]) == INT32_MIN),
"integer divide error");
vm_binop_integer(/);
case DOP_DIVIDE_IMMEDIATE:
{
int32_t op1 = dst_unwrap_integer(stack[oparg(2, 0xFF)]);
int32_t op2 = *((int32_t *)pc) >> 24;
/* Check for degenerate integer division (divide by zero, and dividing
* min value by -1). These checks could be omitted if the arg is not
* 0 or -1. */
if (op2 == 0)
vm_throw("integer divide error");
if (op2 == -1 && op1 == INT32_MIN)
vm_throw("integer divide error");
else
stack[oparg(1, 0xFF)] = dst_wrap_integer(op1 / op2);
pc++;
vm_next();
}
case DOP_DIVIDE_REAL:
vm_binop_real(/);
case DOP_DIVIDE:
{
DstValue op1 = stack[oparg(2, 0xFF)];
DstValue op2 = stack[oparg(3, 0xFF)];
vm_assert(dst_checktype(op1, DST_INTEGER) || dst_checktype(op1, DST_REAL), "expected number");
vm_assert(dst_checktype(op2, DST_INTEGER) || dst_checktype(op2, DST_REAL), "expected number");
if (dst_checktype(op2, DST_INTEGER) && dst_unwrap_integer(op2) == 0)
vm_throw("integer divide error");
if (dst_checktype(op2, DST_INTEGER) && dst_unwrap_integer(op2) == -1 &&
dst_checktype(op1, DST_INTEGER) && dst_unwrap_integer(op1) == INT32_MIN)
vm_throw("integer divide error");
stack[oparg(1, 0xFF)] = dst_checktype(op1, DST_INTEGER)
? (dst_checktype(op2, DST_INTEGER)
? dst_wrap_integer(dst_unwrap_integer(op1) / dst_unwrap_integer(op2))
: dst_wrap_real((double)dst_unwrap_integer(op1) / dst_unwrap_real(op2)))
: (dst_checktype(op2, DST_INTEGER)
? dst_wrap_real(dst_unwrap_real(op1) / (double)dst_unwrap_integer(op2))
: dst_wrap_real(dst_unwrap_real(op1) / dst_unwrap_real(op2)));
pc++;
vm_next();
}
case DOP_BAND:
vm_binop_integer(&);
case DOP_BOR:
vm_binop_integer(|);
case DOP_BXOR:
vm_binop_integer(^);
case DOP_BNOT:
stack[oparg(1, 0xFF)] = dst_wrap_integer(~dst_unwrap_integer(stack[oparg(2, 0xFFFF)]));
vm_next();
case DOP_SHIFT_RIGHT_UNSIGNED:
stack[oparg(1, 0xFF)] = dst_wrap_integer(
(int32_t)(((uint32_t)dst_unwrap_integer(stack[oparg(2, 0xFF)]))
>>
dst_unwrap_integer(stack[oparg(3, 0xFF)]))
);
pc++;
vm_next();
case DOP_SHIFT_RIGHT_UNSIGNED_IMMEDIATE:
stack[oparg(1, 0xFF)] = dst_wrap_integer(
(int32_t) (((uint32_t)dst_unwrap_integer(stack[oparg(2, 0xFF)])) >> oparg(3, 0xFF))
);
pc++;
vm_next();
case DOP_SHIFT_RIGHT:
vm_binop_integer(>>);
case DOP_SHIFT_RIGHT_IMMEDIATE:
stack[oparg(1, 0xFF)] = dst_wrap_integer(
(int32_t)(dst_unwrap_integer(stack[oparg(2, 0xFF)]) >> oparg(3, 0xFF))
);
pc++;
vm_next();
case DOP_SHIFT_LEFT:
vm_binop_integer(<<);
case DOP_SHIFT_LEFT_IMMEDIATE:
stack[oparg(1, 0xFF)] = dst_wrap_integer(
dst_unwrap_integer(stack[oparg(2, 0xFF)]) << oparg(3, 0xFF)
);
pc++;
vm_next();
case DOP_MOVE_NEAR:
stack[oparg(1, 0xFF)] = stack[oparg(2, 0xFFFF)];
pc++;
vm_next();
case DOP_MOVE_FAR:
stack[oparg(2, 0xFFFF)] = stack[oparg(1, 0xFF)];
pc++;
vm_next();
case DOP_JUMP:
pc += (*(int32_t *)pc) >> 8;
vm_next();
case DOP_JUMP_IF:
if (dst_truthy(stack[oparg(1, 0xFF)])) {
pc += (*(int32_t *)pc) >> 16;
} else {
pc++;
}
vm_next();
case DOP_JUMP_IF_NOT:
if (dst_truthy(stack[oparg(1, 0xFF)])) {
pc++;
} else {
pc += (*(int32_t *)pc) >> 16;
}
vm_next();
case DOP_LESS_THAN:
stack[oparg(1, 0xFF)] = dst_wrap_boolean(dst_compare(
stack[oparg(2, 0xFF)],
stack[oparg(3, 0xFF)]
) < 0);
pc++;
vm_next();
case DOP_GREATER_THAN:
stack[oparg(1, 0xFF)] = dst_wrap_boolean(dst_compare(
stack[oparg(2, 0xFF)],
stack[oparg(3, 0xFF)]
) > 0);
pc++;
vm_next();
case DOP_EQUALS:
stack[oparg(1, 0xFF)] = dst_wrap_boolean(dst_equals(
stack[oparg(2, 0xFF)],
stack[oparg(3, 0xFF)]
));
pc++;
vm_next();
case DOP_COMPARE:
stack[oparg(1, 0xFF)] = dst_wrap_integer(dst_compare(
stack[oparg(2, 0xFF)],
stack[oparg(3, 0xFF)]
));
pc++;
vm_next();
case DOP_LOAD_NIL:
stack[oparg(1, 0xFFFFFF)] = dst_wrap_nil();
pc++;
vm_next();
case DOP_LOAD_TRUE:
stack[oparg(1, 0xFFFFFF)] = dst_wrap_boolean(1);
pc++;
vm_next();
case DOP_LOAD_FALSE:
stack[oparg(1, 0xFFFFFF)] = dst_wrap_boolean(0);
pc++;
vm_next();
case DOP_LOAD_INTEGER:
stack[oparg(1, 0xFF)] = dst_wrap_integer(*((int32_t *)pc) >> 16);
pc++;
vm_next();
case DOP_LOAD_CONSTANT:
vm_assert((int32_t)oparg(2, 0xFFFF) < func->def->constants_length, "invalid constant");
stack[oparg(1, 0xFF)] = func->def->constants[(int32_t)oparg(2, 0xFFFF)];
pc++;
vm_next();
case DOP_LOAD_SELF:
stack[oparg(1, 0xFFFFFF)] = dst_wrap_function(func);
pc++;
vm_next();
case DOP_LOAD_UPVALUE:
{
int32_t eindex = oparg(2, 0xFF);
int32_t vindex = oparg(3, 0xFF);
DstFuncEnv *env;
vm_assert(func->def->environments_length > eindex, "invalid upvalue");
env = func->envs[eindex];
vm_assert(env->length > vindex, "invalid upvalue");
if (env->offset) {
/* On stack */
stack[oparg(1, 0xFF)] = env->as.fiber->data[env->offset + vindex];
} else {
/* Off stack */
stack[oparg(1, 0xFF)] = env->as.values[vindex];
}
pc++;
vm_next();
}
case DOP_SET_UPVALUE:
{
int32_t eindex = oparg(2, 0xFF);
int32_t vindex = oparg(3, 0xFF);
DstFuncEnv *env;
vm_assert(func->def->environments_length > eindex, "invalid upvalue");
env = func->envs[eindex];
vm_assert(env->length > vindex, "invalid upvalue");
if (env->offset) {
env->as.fiber->data[env->offset + vindex] = stack[oparg(1, 0xFF)];
} else {
env->as.values[vindex] = stack[oparg(1, 0xFF)];
}
pc++;
vm_next();
}
case DOP_CLOSURE:
{
int32_t i;
DstFunction *fn;
DstFuncDef *fd;
vm_assert((int32_t)oparg(2, 0xFFFF) < func->def->constants_length, "invalid constant");
vm_assert(dst_checktype(func->def->constants[oparg(2, 0xFFFF)], DST_NIL), "constant must be funcdef");
fd = (DstFuncDef *)(dst_unwrap_pointer(func->def->constants[(int32_t)oparg(2, 0xFFFF)]));
fn = dst_gcalloc(DST_MEMORY_FUNCTION, sizeof(DstFunction));
fn->envs = malloc(sizeof(DstFuncEnv *) * fd->environments_length);
if (NULL == fn->envs) {
DST_OUT_OF_MEMORY;
}
if (fd->flags & DST_FUNCDEF_FLAG_NEEDSENV) {
/* Delayed capture of current stack frame */
DstFuncEnv *env = dst_gcalloc(DST_MEMORY_FUNCENV, sizeof(DstFuncEnv));
env->offset = dst_vm_fiber->frame;
env->as.fiber = dst_vm_fiber;
env->length = func->def->slotcount;
fn->envs[0] = env;
} else {
fn->envs[0] = NULL;
}
for (i = 1; i < fd->environments_length; ++i) {
int32_t inherit = fd->environments[i];
fn->envs[i] = func->envs[inherit];
}
stack[oparg(1, 0xFF)] = dst_wrap_function(fn);
pc++;
vm_checkgc_next();
}
case DOP_PUSH:
dst_fiber_push(dst_vm_fiber, stack[oparg(1, 0xFFFFFF)]);
pc++;
vm_checkgc_next();
case DOP_PUSH_2:
dst_fiber_push2(dst_vm_fiber,
stack[oparg(1, 0xFF)],
stack[oparg(2, 0xFFFF)]);
pc++;
vm_checkgc_next();
case DOP_PUSH_3:
dst_fiber_push3(dst_vm_fiber,
stack[oparg(1, 0xFF)],
stack[oparg(2, 0xFF)],
stack[oparg(3, 0xFF)]);
pc++;
vm_checkgc_next();
case DOP_PUSH_ARRAY:
{
int32_t count;
const DstValue *array;
if (dst_seq_view(stack[oparg(1, 0xFFFFFF)], &array, &count)) {
dst_fiber_pushn(dst_vm_fiber, array, count);
} else {
vm_throw("expected array or tuple");
}
pc++;
vm_checkgc_next();
}
case DOP_CALL:
{
DstValue callee = stack[oparg(2, 0xFFFF)];
if (dst_checktype(callee, DST_FUNCTION)) {
func = dst_unwrap_function(callee);
dst_fiber_funcframe(dst_vm_fiber, func);
stack = dst_vm_fiber->data + dst_vm_fiber->frame;
pc = func->def->bytecode;
vm_checkgc_next();
} else if (dst_checktype(callee, DST_CFUNCTION)) {
dst_fiber_cframe(dst_vm_fiber);
retreg = dst_wrap_nil();
if (dst_unwrap_cfunction(callee)(
dst_vm_fiber->frametop - dst_vm_fiber->frame,
dst_vm_fiber->data + dst_vm_fiber->frame,
&retreg)) {
goto vm_error;
}
goto vm_return_cfunc;
}
vm_throw("cannot call non-function type");
}
case DOP_TAILCALL:
{
DstValue callee = stack[oparg(1, 0xFFFFFF)];
if (dst_checktype(callee, DST_FUNCTION)) {
func = dst_unwrap_function(callee);
dst_fiber_funcframe_tail(dst_vm_fiber, func);
stack = dst_vm_fiber->data + dst_vm_fiber->frame;
pc = func->def->bytecode;
vm_checkgc_next();
} else if (dst_checktype(callee, DST_CFUNCTION)) {
dst_fiber_cframe_tail(dst_vm_fiber);
retreg = dst_wrap_nil();
if (dst_unwrap_cfunction(callee)(
dst_vm_fiber->frametop - dst_vm_fiber->frame,
dst_vm_fiber->data + dst_vm_fiber->frame,
&retreg)) {
goto vm_error;
}
goto vm_return_cfunc;
}
vm_throw("expected function");
}
case DOP_TRANSFER:
{
DstFiber *nextfiber;
DstStackFrame *frame = dst_stack_frame(stack);
DstValue temp = stack[oparg(2, 0xFF)];
retreg = stack[oparg(3, 0xFF)];
vm_assert(dst_checktype(temp, DST_FIBER) ||
dst_checktype(temp, DST_NIL), "expected fiber");
nextfiber = dst_checktype(temp, DST_FIBER)
? dst_unwrap_fiber(temp)
: dst_vm_fiber->parent;
/* Check for root fiber */
if (NULL == nextfiber) {
frame->pc = pc;
*returnreg = retreg;
return 0;
}
vm_assert(nextfiber->status == DST_FIBER_PENDING, "can only transfer to pending fiber");
frame->pc = pc;
dst_vm_fiber->status = DST_FIBER_PENDING;
dst_vm_fiber = nextfiber;
vm_init_fiber_state();
stack[oparg(1, 0xFF)] = retreg;
pc++;
vm_next();
}
case DOP_PUT:
dst_put(stack[oparg(1, 0xFF)],
stack[oparg(2, 0xFF)],
stack[oparg(3, 0xFF)]);
++pc;
vm_checkgc_next();
case DOP_PUT_INDEX:
dst_setindex(stack[oparg(1, 0xFF)],
stack[oparg(2, 0xFF)],
oparg(3, 0xFF));
++pc;
vm_next();
case DOP_GET:
stack[oparg(1, 0xFF)] = dst_get(
stack[oparg(2, 0xFF)],
stack[oparg(3, 0xFF)]);
++pc;
vm_next();
case DOP_GET_INDEX:
stack[oparg(1, 0xFF)] = dst_getindex(
stack[oparg(2, 0xFF)],
oparg(3, 0xFF));
++pc;
vm_next();
/* Return from c function. Simpler than retuning from dst function */
vm_return_cfunc:
{
dst_fiber_popframe(dst_vm_fiber);
if (dst_update_fiber()) {
*returnreg = retreg;
return 0;
}
stack[oparg(1, 0xFF)] = retreg;
pc++;
vm_checkgc_next();
}
/* Handle returning from stack frame. Expect return value in fiber->ret */
vm_return:
{
dst_fiber_popframe(dst_vm_fiber);
if (dst_update_fiber()) {
*returnreg = retreg;
return 0;
}
stack = dst_vm_fiber->data + dst_vm_fiber->frame;
pc = dst_stack_frame(stack)->pc;
stack[oparg(1, 0xFF)] = retreg;
pc++;
vm_checkgc_next();
}
/* Handle errors from c functions and vm opcodes */
vm_error:
{
dst_vm_fiber->status = DST_FIBER_ERROR;
if (dst_update_fiber()) {
*returnreg = retreg;
return 1;
}
stack = dst_vm_fiber->data + dst_vm_fiber->frame;
pc = dst_stack_frame(stack)->pc;
stack[oparg(1, 0xFF)] = retreg;
pc++;
vm_checkgc_next();
}
} /* end switch */
} /* end for */
#undef oparg
#undef vm_error
#undef vm_assert
#undef vm_binop
#undef vm_binop_real
#undef vm_binop_integer
#undef vm_binop_immediate
#undef vm_init_fiber_state
}
/* Run the vm with a given function. This function is
* called to start the vm. */
int dst_run(DstValue callee, DstValue *returnreg) {
if (NULL == dst_vm_fiber) {
dst_vm_fiber = dst_fiber(0);
} else {
dst_fiber_reset(dst_vm_fiber);
}
if (dst_checktype(callee, DST_CFUNCTION)) {
*returnreg = dst_wrap_nil();
dst_fiber_cframe(dst_vm_fiber);
return dst_unwrap_cfunction(callee)(
0,
dst_vm_fiber->data + dst_vm_fiber->frame,
returnreg);
} else if (dst_checktype(callee, DST_FUNCTION)) {
dst_fiber_funcframe(dst_vm_fiber, dst_unwrap_function(callee));
return dst_continue(returnreg);
}
*returnreg = dst_cstringv("expected function");
return 1;
}
/* Setup functions */
int dst_init() {
/* Garbage collection */
dst_vm_blocks = NULL;
dst_vm_next_collection = 0;
/* Setting memoryInterval to zero forces
* a collection pretty much every cycle, which is
* horrible for performance, but helps ensure
* there are no memory bugs during dev */
dst_vm_gc_interval = 0x0000000;
dst_symcache_init();
/* Set thread */
dst_vm_fiber = NULL;
/* Initialize gc roots */
dst_vm_roots = NULL;
dst_vm_root_count = 0;
dst_vm_root_capacity = 0;
return 0;
}
/* Clear all memory associated with the VM */
void dst_deinit() {
dst_clear_memory();
dst_vm_fiber = NULL;
dst_symcache_deinit();
free(dst_vm_roots);
dst_vm_roots = NULL;
dst_vm_root_count = 0;
dst_vm_root_capacity = 0;
}
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