1103 lines
41 KiB
Nim
1103 lines
41 KiB
Nim
# Copyright 2022 Mattia Giambirtone & All Contributors
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
# See the License for the specific language governing permissions and
|
|
# limitations under the License.
|
|
## The Peon runtime environment
|
|
import ../config
|
|
|
|
# Sorry, but there only is enough space
|
|
# for one GC in this VM :(
|
|
{.push checks:enableVMChecks.} # The VM is a critical point where checks are deleterious
|
|
when defined(gcOrc):
|
|
GC_disableOrc()
|
|
when not defined(gcArc) and not defined(gcOrc):
|
|
GC_disable()
|
|
GC_disableMarkAndSweep()
|
|
|
|
|
|
import std/math
|
|
import std/segfaults
|
|
import std/strutils
|
|
import std/sets
|
|
import std/monotimes
|
|
|
|
|
|
import ../frontend/meta/bytecode
|
|
import ../util/multibyte
|
|
|
|
|
|
when debugVM or debugMem or debugGC:
|
|
import std/strformat
|
|
import std/sequtils
|
|
import std/terminal
|
|
|
|
when debugVM:
|
|
proc clearerr(stream: File) {.header: "stdio.h", importc.}
|
|
|
|
|
|
type
|
|
ObjectKind* = enum
|
|
## A tag for heap-allocated
|
|
## peon objects
|
|
String, List,
|
|
Dict, Tuple,
|
|
CustomType,
|
|
HeapObject* = object
|
|
## A tagged box for a heap-allocated
|
|
## peon object
|
|
marked*: bool # Used in the GC phase
|
|
case kind*: ObjectKind
|
|
of String:
|
|
str*: ptr UncheckedArray[char]
|
|
len*: int
|
|
else:
|
|
discard # TODO
|
|
PeonGC* = object
|
|
## A simple Mark&Sweep collector
|
|
## to manage peon's heap space.
|
|
## All heap allocation goes through
|
|
## this system and is not handled
|
|
## manually by the VM
|
|
bytesAllocated: tuple[total, current: int]
|
|
cycles: int
|
|
nextGC: int
|
|
pointers: HashSet[uint64]
|
|
objects: seq[ptr HeapObject]
|
|
PeonVM* = object
|
|
## The Peon Virtual Machine.
|
|
## Note how the only data
|
|
## type we handle here is
|
|
## a 64-bit unsigned integer:
|
|
## This is to allow the use
|
|
## of unboxed primitive types.
|
|
## For more complex types, the
|
|
## value represents a pointer to
|
|
## some stack- or heap-allocated
|
|
## object. The VM has no concept
|
|
## of type by itself: everything
|
|
## is lost after the compilation
|
|
## phase
|
|
ip: uint64 # The instruction pointer
|
|
chunk: Chunk # The chunk of bytecode to execute
|
|
calls: seq[uint64] # The call stack
|
|
operands: seq[uint64] # The operand stack
|
|
cache: array[6, uint64] # The singletons cache
|
|
frames: seq[uint64] # Stores the bottom of stack frames
|
|
closures: seq[uint64] # Stores closure environment offsets
|
|
envs: seq[uint64] # Stores closure variables
|
|
results: seq[uint64] # Stores function return values
|
|
gc: PeonGC # A reference to the VM's garbage collector
|
|
breakpoints: seq[uint64] # Breakpoints where we call our debugger
|
|
debugNext: bool # Whether to debug the next instruction
|
|
lastDebugCommand: string # The last debugging command input by the user
|
|
|
|
|
|
# Implementation of peon's memory manager
|
|
|
|
proc newPeonGC*: PeonGC =
|
|
## Initializes a new, blank
|
|
## garbage collector
|
|
result.bytesAllocated = (0, 0)
|
|
result.objects = @[]
|
|
result.nextGC = FirstGC
|
|
result.cycles = 0
|
|
|
|
|
|
proc collect*(self: var PeonVM)
|
|
|
|
|
|
proc reallocate*(self: var PeonVM, p: pointer, oldSize: int, newSize: int): pointer =
|
|
## Simple wrapper around realloc with
|
|
## built-in garbage collection
|
|
self.gc.bytesAllocated.current += newSize - oldSize
|
|
try:
|
|
if newSize == 0 and not p.isNil():
|
|
when debugMem:
|
|
if oldSize > 1:
|
|
echo &"DEBUG - MM: Deallocating {oldSize} bytes of memory"
|
|
else:
|
|
echo "DEBUG - MM: Deallocating 1 byte of memory"
|
|
elif (oldSize > 0 and not p.isNil() and newSize > oldSize) or oldSize == 0:
|
|
when debugMem:
|
|
if oldSize == 0:
|
|
if newSize > 1:
|
|
echo &"DEBUG - MM: Allocating {newSize} bytes of memory"
|
|
else:
|
|
echo "DEBUG - MM: Allocating 1 byte of memory"
|
|
else:
|
|
echo &"DEBUG - M: Resizing {oldSize} bytes of memory to {newSize} bytes"
|
|
self.gc.bytesAllocated.total += newSize - oldSize
|
|
when debugStressGC:
|
|
self.collect()
|
|
else:
|
|
if self.gc.bytesAllocated.current > self.gc.nextGC:
|
|
self.collect()
|
|
result = realloc(p, newSize)
|
|
except NilAccessDefect:
|
|
stderr.writeLine("Peon: could not manage memory, segmentation fault")
|
|
quit(139) # For now, there's not much we can do if we can't get the memory we need, so we exit
|
|
|
|
|
|
template resizeArray*(self: var PeonVM, kind: untyped, p: pointer, oldCount, newCount: int): untyped =
|
|
## Handy template to resize a dynamic array
|
|
cast[ptr UncheckedArray[kind]](reallocate(self, p, sizeof(kind) * oldCount, sizeof(kind) * newCount))
|
|
|
|
|
|
template freeArray*(self: var PeonVM, kind: untyped, p: pointer, size: int): untyped =
|
|
## Frees a dynamic array
|
|
discard reallocate(self, p, sizeof(kind) * size, 0)
|
|
|
|
|
|
template free*(self: var PeonVM, kind: typedesc, p: pointer): untyped =
|
|
## Frees a pointer by reallocating its
|
|
## size to 0
|
|
discard reallocate(self, p, sizeof(kind), 0)
|
|
|
|
|
|
template setKind*[T, K](t: var T, kind: untyped, target: K) =
|
|
## Thanks to https://forum.nim-lang.org/t/8312
|
|
cast[ptr K](cast[int](addr t) + offsetOf(typeof(t), kind))[] = target
|
|
|
|
|
|
proc allocate*(self: var PeonVM, kind: ObjectKind, size: typedesc, count: int): ptr HeapObject {.inline.} =
|
|
## Allocates an object on the heap
|
|
result = cast[ptr HeapObject](self.reallocate(nil, 0, sizeof(HeapObject)))
|
|
setkind(result[], kind, kind)
|
|
result.marked = false
|
|
case kind:
|
|
of String:
|
|
result.str = cast[ptr UncheckedArray[char]](self.reallocate(nil, 0, sizeof(size) * count))
|
|
result.len = count
|
|
else:
|
|
discard # TODO
|
|
self.gc.objects.add(result)
|
|
self.gc.pointers.incl(cast[uint64](result))
|
|
when debugAlloc:
|
|
echo &"DEBUG - GC: Allocated new object: {result[]}"
|
|
echo &"DEBUG - GC: Current heap size: {self.gc.bytesAllocated.current}"
|
|
echo &"DEBUG - GC: Total bytes allocated: {self.gc.bytesAllocated.total}"
|
|
echo &"DEBUG - GC: Tracked objects: {self.gc.pointers.len()}"
|
|
echo &"DEBUG - GC: Completed GC cycles: {self.gc.cycles}"
|
|
|
|
|
|
proc mark(self: ptr HeapObject): bool =
|
|
## Marks a single object
|
|
if self.marked:
|
|
return false
|
|
self.marked = true
|
|
return true
|
|
|
|
|
|
proc markRoots(self: var PeonVM): seq[ptr HeapObject] =
|
|
## Marks root objects *not* to be
|
|
## collected by the GC and returns
|
|
## their addresses
|
|
when debugGC:
|
|
echo "DEBUG - GC: Starting mark phase"
|
|
# Unlike what bob does in his book,
|
|
# we keep track of objects in a different
|
|
# way due to the difference of our design.
|
|
# Specifically, we don't have neat structs for
|
|
# all peon objects: When we allocate() an object,
|
|
# we keep track of the small wrapper it created
|
|
# along with its type and other metadata. Then,
|
|
# we can go through the various sources of roots
|
|
# in the VM, see if they match any pointers we
|
|
# already know about (we store them in a hash set so
|
|
# it's really fast), and then we can be sure that
|
|
# anything that's in the difference (i.e. mathematical
|
|
# set difference) between our full list of pointers
|
|
# and the live ones is not a root object, so if it's
|
|
# not indirectly reachable through a root itself, it
|
|
# can be freed. I'm not sure if I can call this GC
|
|
# strategy precise, since technically there is a chance
|
|
# for a regular value to collide with one of the pointers
|
|
# we allocated and that would cause a memory leak, but
|
|
# with a 64-bit address-space it probably hardly matters,
|
|
# so I guess this is a mostly-precise Mark&Sweep collector
|
|
var live = initHashSet[uint64](self.gc.pointers.len())
|
|
for obj in self.calls:
|
|
if obj in self.gc.pointers:
|
|
live.incl(obj)
|
|
for obj in self.operands:
|
|
if obj in self.gc.pointers:
|
|
live.incl(obj)
|
|
for obj in self.envs:
|
|
if obj in self.gc.pointers:
|
|
live.incl(obj)
|
|
# We preallocate the space on the seq
|
|
result = newSeqOfCap[ptr HeapObject](len(live))
|
|
var obj: ptr HeapObject
|
|
for p in live:
|
|
obj = cast[ptr HeapObject](p)
|
|
if obj.mark():
|
|
result.add(obj)
|
|
when debugGC:
|
|
echo &"DEBUG - GC: Marked object: {obj[]}"
|
|
when debugGC:
|
|
echo "DEBUG - GC: Mark phase complete"
|
|
|
|
|
|
proc trace(self: var PeonVM, roots: seq[ptr HeapObject]) =
|
|
## Traces references to other
|
|
## objects starting from the
|
|
## roots. The second argument
|
|
## is the output of the mark
|
|
## phase. To speak in terms
|
|
## of the tricolor abstraction,
|
|
## this is where we blacken gray
|
|
## objects
|
|
when debugGC:
|
|
echo &"DEBUG - GC: Tracing indirect references from {len(roots)} roots"
|
|
var count = 0
|
|
for root in roots:
|
|
case root.kind:
|
|
of String:
|
|
discard # Strings hold no additional references
|
|
else:
|
|
discard # TODO: Other types
|
|
when debugGC:
|
|
echo &"DEBUG - GC: Traced {count} indirect references"
|
|
|
|
|
|
proc free(self: var PeonVM, obj: ptr HeapObject) =
|
|
## Frees a single heap-allocated
|
|
## peon object and all the memory
|
|
## it directly or indirectly owns
|
|
when debugAlloc:
|
|
echo &"DEBUG - GC: Freeing object: {obj[]}"
|
|
case obj.kind:
|
|
of String:
|
|
# Strings only own their
|
|
# underlying character array
|
|
if obj.len > 0 and not obj.str.isNil():
|
|
self.freeArray(char, obj.str, obj.len)
|
|
else:
|
|
discard # TODO
|
|
self.free(HeapObject, obj)
|
|
self.gc.pointers.excl(cast[uint64](obj))
|
|
when debugAlloc:
|
|
echo &"DEBUG - GC: Current heap size: {self.gc.bytesAllocated.current}"
|
|
echo &"DEBUG - GC: Total bytes allocated: {self.gc.bytesAllocated.total}"
|
|
echo &"DEBUG - GC: Tracked objects: {self.gc.pointers.len()}"
|
|
echo &"DEBUG - GC: Completed GC cycles: {self.gc.cycles}"
|
|
|
|
|
|
proc sweep(self: var PeonVM) =
|
|
## Sweeps unmarked objects
|
|
## that have been left behind
|
|
## during the mark phase.
|
|
## This is more convoluted
|
|
## than it needs to be because
|
|
## nim disallows changing the
|
|
## size of a sequence during
|
|
## iteration
|
|
when debugGC:
|
|
echo "DEBUG - GC: Beginning sweeping phase"
|
|
var j = -1
|
|
var idx = 0
|
|
when debugGC:
|
|
var count = 0
|
|
while j < self.gc.objects.high():
|
|
inc(j)
|
|
if self.gc.objects[j].marked:
|
|
# Object is marked: don't touch it,
|
|
# but reset its mark so that it doesn't
|
|
# stay alive forever
|
|
when debugGC:
|
|
echo &"DEBUG - GC: Unmarking object: {self.gc.objects[j][]}"
|
|
self.gc.objects[j].marked = false
|
|
inc(idx)
|
|
else:
|
|
# Object is unmarked: its memory is
|
|
# fair game
|
|
self.free(self.gc.objects[idx])
|
|
self.gc.objects.delete(idx)
|
|
inc(idx)
|
|
when debugGC:
|
|
inc(count)
|
|
when debugGC:
|
|
echo &"DEBUG - GC: Swept {count} objects"
|
|
|
|
|
|
proc collect(self: var PeonVM) =
|
|
## Attempts to reclaim some
|
|
## memory from unreachable
|
|
## objects onto the heap
|
|
when debugGC:
|
|
let before = self.gc.bytesAllocated.current
|
|
let time = getMonoTime().ticks().float() / 1_000_000
|
|
echo &"DEBUG - GC: Starting collection cycle at heap size {self.gc.bytesAllocated.current}"
|
|
inc(self.gc.cycles)
|
|
self.trace(self.markRoots())
|
|
self.sweep()
|
|
self.gc.nextGC = self.gc.bytesAllocated.current * HeapGrowFactor
|
|
when debugGC:
|
|
echo &"DEBUG - GC: Collection cycle has terminated in {getMonoTime().ticks().float() / 1_000_000 - time:.2f} ms, collected {before - self.gc.bytesAllocated.current} bytes of memory in total"
|
|
echo &"DEBUG - GC: Next cycle at {self.gc.nextGC} bytes"
|
|
|
|
|
|
# Implementation of the peon VM
|
|
|
|
proc initCache*(self: var PeonVM) =
|
|
## Initializes the VM's
|
|
## singletons cache
|
|
self.cache[0] = 0x0 # False
|
|
self.cache[1] = 0x1 # True
|
|
self.cache[2] = 0x2 # Nil
|
|
self.cache[3] = 0x3 # Positive inf
|
|
self.cache[4] = 0x4 # Negative inf
|
|
self.cache[5] = 0x5 # NaN
|
|
|
|
|
|
proc newPeonVM*: PeonVM =
|
|
## Initializes a new, blank VM
|
|
## for executing Peon bytecode
|
|
result.ip = 0
|
|
result.initCache()
|
|
result.gc = newPeonGC()
|
|
result.frames = @[]
|
|
result.operands = @[]
|
|
result.results = @[]
|
|
result.envs = @[]
|
|
result.calls = @[]
|
|
|
|
|
|
# Getters for singleton types
|
|
{.push inline.}
|
|
|
|
proc getNil*(self: var PeonVM): uint64 = self.cache[2]
|
|
|
|
proc getBool*(self: var PeonVM, value: bool): uint64 =
|
|
if value:
|
|
return self.cache[1]
|
|
return self.cache[0]
|
|
|
|
proc getInf*(self: var PeonVM, positive: bool): uint64 =
|
|
if positive:
|
|
return self.cache[3]
|
|
return self.cache[4]
|
|
|
|
proc getNan*(self: var PeonVM): uint64 = self.cache[5]
|
|
|
|
|
|
# Thanks to nim's *genius* idea of making x > y a template
|
|
# for y < x (which by itself is fine) together with the fact
|
|
# that the order of evaluation of templates with the same
|
|
# expression is fucking stupid (see https://nim-lang.org/docs/manual.html#order-of-evaluation
|
|
# and https://github.com/nim-lang/Nim/issues/10425 and try not to
|
|
# bang your head against the nearest wall), we need a custom operator
|
|
# that preserves the natural order of evaluation
|
|
proc `!>`[T](a, b: T): auto {.inline.} =
|
|
b < a
|
|
|
|
|
|
proc `!>=`[T](a, b: T): auto {.inline, used.} =
|
|
b <= a
|
|
|
|
|
|
# Stack primitives. Note: all accesses to the call stack
|
|
# that go through the getc/setc wrappers are frame-relative,
|
|
# meaning that the index is added to the current stack frame's
|
|
# bottom to obtain an absolute stack index
|
|
proc push(self: var PeonVM, obj: uint64) =
|
|
## Pushes a value object onto the
|
|
## operand stack
|
|
self.operands.add(obj)
|
|
|
|
|
|
proc pop(self: var PeonVM): uint64 =
|
|
## Pops a value off the operand
|
|
## stack and returns it
|
|
return self.operands.pop()
|
|
|
|
|
|
proc peekb(self: PeonVM, distance: BackwardsIndex = ^1): uint64 =
|
|
## Returns the value at the given (backwards)
|
|
## distance from the top of the operand stack
|
|
## without consuming it
|
|
return self.operands[distance]
|
|
|
|
|
|
proc peek(self: PeonVM, distance: int = 0): uint64 =
|
|
## Returns the value at the given
|
|
## distance from the top of the
|
|
## operand stack without consuming it
|
|
if distance < 0:
|
|
return self.peekb(^(-int(distance)))
|
|
return self.operands[self.operands.high() + distance]
|
|
|
|
|
|
proc pushc(self: var PeonVM, val: uint64) =
|
|
## Pushes a value onto the
|
|
## call stack
|
|
self.calls.add(val)
|
|
|
|
|
|
proc popc(self: var PeonVM): uint64 =
|
|
## Pops a value off the call
|
|
## stack and returns it
|
|
return self.calls.pop()
|
|
|
|
|
|
proc peekc(self: PeonVM, distance: int = 0): uint64 {.used.} =
|
|
## Returns the value at the given
|
|
## distance from the top of the
|
|
## call stack without consuming it
|
|
return self.calls[self.calls.high() + distance]
|
|
|
|
|
|
proc getc(self: PeonVM, idx: int): uint64 =
|
|
## Getter method that abstracts
|
|
## indexing our call stack through
|
|
## stack frames
|
|
return self.calls[idx.uint64 + self.frames[^1]]
|
|
|
|
|
|
proc setc(self: var PeonVM, idx: int, val: uint64) =
|
|
## Setter method that abstracts
|
|
## indexing our call stack through
|
|
## stack frames
|
|
self.calls[idx.uint + self.frames[^1]] = val
|
|
|
|
|
|
proc getClosure(self: PeonVM, idx: int): uint64 =
|
|
## Getter method that abstracts
|
|
## indexing closure environments
|
|
return self.envs[idx.uint + self.closures[^1]]
|
|
|
|
|
|
proc setClosure(self: var PeonVM, idx: int, val: uint64) =
|
|
## Setter method that abstracts
|
|
## indexing closure environments
|
|
if idx == self.envs.len():
|
|
self.envs.add(val)
|
|
else:
|
|
self.envs[idx.uint + self.closures[^1]] = val
|
|
|
|
|
|
proc popClosure(self: var PeonVM, idx: int): uint64 =
|
|
## Pop method that abstracts
|
|
## popping values off closure
|
|
## environments
|
|
var idx = idx.uint + self.closures[^1]
|
|
result = self.envs[idx]
|
|
self.envs.delete(idx)
|
|
|
|
|
|
# Byte-level primitives to read and decode
|
|
# bytecode
|
|
|
|
proc readByte(self: var PeonVM): uint8 =
|
|
## Reads a single byte from the
|
|
## bytecode and returns it as an
|
|
## unsigned 8 bit integer
|
|
inc(self.ip)
|
|
return self.chunk.code[self.ip - 1]
|
|
|
|
|
|
proc readShort(self: var PeonVM): uint16 =
|
|
## Reads two bytes from the
|
|
## bytecode and returns them
|
|
## as an unsigned 16 bit
|
|
## integer
|
|
return [self.readByte(), self.readByte()].fromDouble()
|
|
|
|
|
|
proc readLong(self: var PeonVM): uint32 =
|
|
## Reads three bytes from the
|
|
## bytecode and returns them
|
|
## as an unsigned 32 bit
|
|
## integer. Note however that
|
|
## the boundary is capped at
|
|
## 24 bits instead of 32
|
|
return uint32([self.readByte(), self.readByte(), self.readByte()].fromTriple())
|
|
|
|
|
|
proc readUInt(self: var PeonVM): uint32 {.used.} =
|
|
## Reads three bytes from the
|
|
## bytecode and returns them
|
|
## as an unsigned 32 bit
|
|
## integer
|
|
return uint32([self.readByte(), self.readByte(), self.readByte(), self.readByte()].fromQuad())
|
|
|
|
|
|
# Functions to read primitives from the chunk's
|
|
# constants table
|
|
|
|
proc constReadInt64(self: var PeonVM, idx: int): int64 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an int64
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1],
|
|
self.chunk.consts[idx + 2], self.chunk.consts[idx + 3],
|
|
self.chunk.consts[idx + 4], self.chunk.consts[idx + 5],
|
|
self.chunk.consts[idx + 6], self.chunk.consts[idx + 7],
|
|
]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadUInt64(self: var PeonVM, idx: int): uint64 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an uint64
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1],
|
|
self.chunk.consts[idx + 2], self.chunk.consts[idx + 3],
|
|
self.chunk.consts[idx + 4], self.chunk.consts[idx + 5],
|
|
self.chunk.consts[idx + 6], self.chunk.consts[idx + 7],
|
|
]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadUInt32(self: var PeonVM, idx: int): uint32 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an int32
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1],
|
|
self.chunk.consts[idx + 2], self.chunk.consts[idx + 3]]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadInt32(self: var PeonVM, idx: int): int32 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an uint32
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1],
|
|
self.chunk.consts[idx + 2], self.chunk.consts[idx + 3]]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadInt16(self: var PeonVM, idx: int): int16 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an int16
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1]]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadUInt16(self: var PeonVM, idx: int): uint16 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an uint16
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1]]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadInt8(self: var PeonVM, idx: int): int8 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an int8
|
|
result = int8(self.chunk.consts[idx])
|
|
|
|
|
|
proc constReadUInt8(self: var PeonVM, idx: int): uint8 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as an uint8
|
|
result = self.chunk.consts[idx]
|
|
|
|
|
|
proc constReadFloat32(self: var PeonVM, idx: int): float32 =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as a float32
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1],
|
|
self.chunk.consts[idx + 2], self.chunk.consts[idx + 3]]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadFloat64(self: var PeonVM, idx: int): float =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as a float
|
|
var arr = [self.chunk.consts[idx], self.chunk.consts[idx + 1],
|
|
self.chunk.consts[idx + 2], self.chunk.consts[idx + 3],
|
|
self.chunk.consts[idx + 4], self.chunk.consts[idx + 5],
|
|
self.chunk.consts[idx + 6], self.chunk.consts[idx + 7]]
|
|
copyMem(result.addr, arr.addr, sizeof(arr))
|
|
|
|
|
|
proc constReadString(self: var PeonVM, size, idx: int): ptr HeapObject =
|
|
## Reads a constant from the
|
|
## chunk's constant table and
|
|
## returns it as a pointer to
|
|
## a heap-allocated string
|
|
let str = self.chunk.consts[idx..<idx + size].fromBytes()
|
|
result = self.allocate(String, char, len(str))
|
|
for i, c in str:
|
|
result.str[i] = c
|
|
|
|
|
|
{.pop.}
|
|
|
|
|
|
when debugVM: # So nim shuts up
|
|
proc debug(self: var PeonVM) =
|
|
## Implements the VM's runtime
|
|
## debugger
|
|
styledEcho fgMagenta, "IP: ", fgYellow, &"{self.ip}"
|
|
styledEcho fgBlue, "Instruction: ", fgRed, &"{OpCode(self.chunk.code[self.ip])} (", fgYellow, $self.chunk.code[self.ip], fgRed, ")"
|
|
var command = ""
|
|
while true:
|
|
stdout.styledWrite(fgGreen, "=> ")
|
|
stdout.flushFile()
|
|
try:
|
|
command = readLine(stdin)
|
|
except EOFError:
|
|
styledEcho(fgYellow, "Use Ctrl+C to exit")
|
|
clearerr(stdin)
|
|
break
|
|
except IOError:
|
|
styledEcho(fgRed, "An error occurred while reading command: ", fgYellow, getCurrentExceptionMsg())
|
|
break
|
|
if command == "":
|
|
if self.lastDebugCommand == "":
|
|
command = "n"
|
|
else:
|
|
command = self.lastDebugCommand
|
|
case command:
|
|
of "n", "next":
|
|
self.debugNext = true
|
|
break
|
|
of "c", "continue":
|
|
self.debugNext = false
|
|
break
|
|
of "s", "stack":
|
|
stdout.styledWrite(fgGreen, "Call Stack: ", fgMagenta, "[")
|
|
for i, e in self.calls:
|
|
stdout.styledWrite(fgYellow, $e)
|
|
if i < self.calls.high():
|
|
stdout.styledWrite(fgYellow, ", ")
|
|
styledEcho fgMagenta, "]"
|
|
of "o", "operands":
|
|
stdout.styledWrite(fgBlue, "Operand Stack: ", fgMagenta, "[")
|
|
for i, e in self.operands:
|
|
stdout.styledWrite(fgYellow, $e)
|
|
if i < self.operands.high():
|
|
stdout.styledWrite(fgYellow, ", ")
|
|
styledEcho fgMagenta, "]"
|
|
of "f", "frame":
|
|
stdout.styledWrite(fgCyan, "Current Frame: ", fgMagenta, "[")
|
|
if self.frames.len() > 0:
|
|
for i, e in self.calls[self.frames[^1]..^1]:
|
|
stdout.styledWrite(fgYellow, $e)
|
|
if i < (self.calls.high() - self.frames[^1].int):
|
|
stdout.styledWrite(fgYellow, ", ")
|
|
styledEcho fgMagenta, "]", fgCyan
|
|
of "frames":
|
|
stdout.styledWrite(fgRed, "Live stack frames: ", fgMagenta, "[")
|
|
for i, e in self.frames:
|
|
stdout.styledWrite(fgYellow, $e)
|
|
if i < self.frames.high():
|
|
stdout.styledWrite(fgYellow, ", ")
|
|
styledEcho fgMagenta, "]"
|
|
of "cl", "closures":
|
|
stdout.styledWrite(fgBlue, "Closure offsets: ", fgMagenta, "[")
|
|
for i, e in self.closures:
|
|
stdout.styledWrite(fgYellow, $e)
|
|
if i < self.closures.high():
|
|
stdout.styledWrite(fgYellow, ", ")
|
|
styledEcho fgMagenta, "]"
|
|
of "e", "env", "environments":
|
|
stdout.styledWrite(fgGreen, "Environments: ", fgMagenta, "[")
|
|
for i, e in self.envs:
|
|
stdout.styledWrite(fgYellow, $e)
|
|
if i < self.envs.high():
|
|
stdout.styledWrite(fgYellow, ", ")
|
|
styledEcho fgMagenta, "]"
|
|
of "r", "results":
|
|
stdout.styledWrite(fgYellow, "Function Results: ", fgMagenta, "[")
|
|
for i, e in self.results:
|
|
stdout.styledWrite(fgYellow, $e)
|
|
if i < self.results.high():
|
|
stdout.styledWrite(fgYellow, ", ")
|
|
styledEcho fgMagenta, "]"
|
|
of "clear":
|
|
stdout.write("\x1Bc")
|
|
else:
|
|
styledEcho(fgRed, "Unknown command ", fgYellow, &"'{command}'")
|
|
|
|
|
|
proc dispatch*(self: var PeonVM) =
|
|
## Main bytecode dispatch loop
|
|
var instruction {.register.}: OpCode
|
|
while true:
|
|
{.computedgoto.} # https://nim-lang.org/docs/manual.html#pragmas-computedgoto-pragma
|
|
when debugVM:
|
|
if self.ip in self.breakpoints or self.breakpoints.len() == 0 or self.debugNext:
|
|
self.debug()
|
|
instruction = OpCode(self.readByte())
|
|
case instruction:
|
|
# Constant loading instructions
|
|
of LoadTrue:
|
|
self.push(self.getBool(true))
|
|
of LoadFalse:
|
|
self.push(self.getBool(false))
|
|
of LoadNan:
|
|
self.push(self.getNan())
|
|
of LoadNil:
|
|
self.push(self.getNil())
|
|
of LoadInf:
|
|
self.push(self.getInf(true))
|
|
of LoadNInf:
|
|
self.push(self.getInf(false))
|
|
of LoadInt64:
|
|
self.push(uint64(self.constReadInt64(int(self.readLong()))))
|
|
of LoadUInt64:
|
|
self.push(uint64(self.constReadUInt64(int(self.readLong()))))
|
|
of LoadUInt32:
|
|
self.push(uint64(self.constReadUInt32(int(self.readLong()))))
|
|
of LoadInt32:
|
|
self.push(uint64(self.constReadInt32(int(self.readLong()))))
|
|
of LoadInt16:
|
|
self.push(uint64(self.constReadInt16(int(self.readLong()))))
|
|
of LoadUInt16:
|
|
self.push(uint64(self.constReadUInt16(int(self.readLong()))))
|
|
of LoadInt8:
|
|
self.push(uint64(self.constReadInt8(int(self.readLong()))))
|
|
of LoadUInt8:
|
|
self.push(uint64(self.constReadUInt8(int(self.readLong()))))
|
|
of LoadString:
|
|
self.push(cast[uint64](self.constReadString(int(self.readLong()), int(self.readLong()))))
|
|
# We cast instead of converting because, unlike with integers,
|
|
# we don't want nim to touch any of the bits of the underlying
|
|
# value!
|
|
of LoadFloat32:
|
|
self.push(cast[uint64](self.constReadFloat32(int(self.readLong()))))
|
|
of LoadFloat64:
|
|
self.push(cast[uint64](self.constReadFloat64(int(self.readLong()))))
|
|
of Call:
|
|
# Calls a peon function. The calling convention here
|
|
# is pretty simple: the first value in the frame is
|
|
# the new instruction pointer to jump to, then a
|
|
# 64-bit return address follows. After that, all
|
|
# arguments and locals follow. Note that, due to
|
|
# how the stack works, all arguments before the call
|
|
# are in the reverse order in which they are passed
|
|
# to the function
|
|
let argc = self.readLong().int
|
|
let retAddr = self.peek(-argc - 1) # Return address
|
|
let jmpAddr = self.peek(-argc - 2) # Function address
|
|
self.ip = jmpAddr
|
|
self.pushc(jmpAddr)
|
|
self.pushc(retAddr)
|
|
# Creates a new result slot for the
|
|
# function's return value
|
|
self.results.add(self.getNil())
|
|
# Creates a new call frame
|
|
self.frames.add(uint64(self.calls.len() - 2))
|
|
# Loads the arguments onto the stack
|
|
for _ in 0..<argc:
|
|
self.pushc(self.pop())
|
|
# Pops the function and return address
|
|
# off the operand stack since they're
|
|
# not needed there anymore
|
|
discard self.pop()
|
|
discard self.pop()
|
|
of CallClosure:
|
|
# Calls a peon closure. The code here is
|
|
# mostly identical to the one for Call,
|
|
# but we also create a new environment
|
|
# containing the function's closed-over variables
|
|
let argc = self.readLong().int
|
|
let offset = self.readLong().uint64
|
|
let retAddr = self.peek(-argc - 1) # Return address
|
|
let jmpAddr = self.peek(-argc - 2) # Function address
|
|
self.ip = jmpAddr
|
|
self.pushc(jmpAddr)
|
|
self.pushc(retAddr)
|
|
# Creates a new result slot for the
|
|
# function's return value
|
|
self.results.add(self.getNil())
|
|
# Creates a new call frame
|
|
self.frames.add(uint64(self.calls.len() - 2))
|
|
self.closures.add(offset - 1)
|
|
# Loads the arguments onto the stack
|
|
for _ in 0..<argc:
|
|
self.pushc(self.pop())
|
|
# Pops the function and return address
|
|
# off the operand stack since they're
|
|
# not needed there anymore
|
|
discard self.pop()
|
|
discard self.pop()
|
|
of Return:
|
|
# Returns from a function.
|
|
# Every peon program is wrapped
|
|
# in a hidden function, so this
|
|
# will also exit the VM if we're
|
|
# at the end of the program
|
|
let ret = self.popc() # Return address
|
|
discard self.popc() # Function address
|
|
if self.readByte() == 1:
|
|
# Function is non-void!
|
|
self.push(self.results.pop())
|
|
else:
|
|
discard self.results.pop()
|
|
# Discard the topmost stack frame
|
|
discard self.frames.pop()
|
|
if self.frames.len() == 0:
|
|
# End of the program!
|
|
return
|
|
# We change the instruction
|
|
# pointer just now because
|
|
# if we did it beforehand,
|
|
# our readByte() call would've
|
|
# read from the wrong offset
|
|
self.ip = ret
|
|
of SetResult:
|
|
# Sets the result of the
|
|
# current function. A Return
|
|
# instruction will pop this
|
|
# off the results array and
|
|
# onto the operand stack when
|
|
# the current function exits
|
|
self.results[self.frames.high()] = self.pop()
|
|
of StoreVar:
|
|
# Stores the value at the top of the operand stack
|
|
# into the given call stack index
|
|
let idx = self.readLong()
|
|
when debugVM:
|
|
assert idx.int - self.calls.high() <= 1, "StoreVar index is bigger than the length of the call stack"
|
|
if idx + self.frames[^1] <= self.calls.high().uint:
|
|
self.setc(idx.int, self.pop())
|
|
else:
|
|
self.pushc(self.pop())
|
|
of LoadClosure:
|
|
# Loads a closed-over variable from the current
|
|
# environment onto the operand stack
|
|
self.push(self.getClosure(self.readLong().int))
|
|
of PopClosure:
|
|
# Discards a closed-over variable from the
|
|
# current environment
|
|
discard self.popClosure(self.readLong().int)
|
|
of StoreClosure:
|
|
# Stores/updates the value of a closed-over
|
|
# variable
|
|
let item = self.getc(self.readLong().int)
|
|
self.setClosure(self.readLong().int, item)
|
|
of LoadVar:
|
|
# Pushes a variable from the call stack
|
|
# onto the operand stack
|
|
self.push(self.getc(self.readLong().int))
|
|
of NoOp:
|
|
# Does nothing
|
|
continue
|
|
of PopC:
|
|
# Pops a value off the call stack
|
|
discard self.popc()
|
|
of Pop:
|
|
# Pops a value off the operand stack
|
|
discard self.pop()
|
|
of PushC:
|
|
# Pushes a value from the operand stack
|
|
# onto the call stack
|
|
self.pushc(self.pop())
|
|
of PopRepl:
|
|
# Pops a peon object off the
|
|
# operand stack and prints it.
|
|
# Used in interactive REPL mode
|
|
if self.frames.len() !> 1:
|
|
discard self.pop()
|
|
continue
|
|
echo self.pop()
|
|
of PopN:
|
|
# Pops N elements off the call stack
|
|
for _ in 0..<int(self.readShort()):
|
|
discard self.popc()
|
|
# Jump opcodes
|
|
of Jump:
|
|
# Absolute jump
|
|
self.ip = self.readLong()
|
|
of JumpForwards:
|
|
# Relative, forward-jump
|
|
self.ip += self.readLong()
|
|
of JumpBackwards:
|
|
# Relative, backward-jump
|
|
self.ip -= self.readLong()
|
|
of JumpIfFalse:
|
|
# Conditional, forward-jump
|
|
if not self.peek().bool:
|
|
self.ip += self.readLong()
|
|
of JumpIfTrue:
|
|
# Conditional (if the top of the stack
|
|
# equals true), forward-jump
|
|
let ip = self.readLong()
|
|
if self.peek().bool:
|
|
self.ip += ip
|
|
of JumpIfFalsePop:
|
|
# Conditional (if the top of the stack
|
|
# equals false), forward-jump. Always
|
|
# pops off the operand stack
|
|
let ip = self.readLong()
|
|
if not self.pop().bool:
|
|
self.ip += ip
|
|
of JumpIfFalseOrPop:
|
|
# Conditional (if the top of the stack
|
|
# equals false), forward-jump. Pops off
|
|
# the operand stack if the value at the
|
|
# top of the operand stack is true
|
|
let ip = self.readLong()
|
|
if not self.peek().bool:
|
|
self.ip += ip
|
|
else:
|
|
discard self.pop()
|
|
# Built-in operations on primitive types.
|
|
# Note that, for operations where the order
|
|
# of the operands matters, we don't need to
|
|
# swap the order of the calls to pop: this
|
|
# is because operators are handled like peon
|
|
# functions, which means the arguments are
|
|
# already reversed on the stack when we
|
|
# execute the instruction. The beauty of the
|
|
# 2's complement system is that for most integer
|
|
# types, we don't need specialized instructions
|
|
# to operate on them
|
|
of Negate:
|
|
self.push(cast[uint64](-int64(self.pop())))
|
|
of NegateFloat64:
|
|
self.push(cast[uint64](-cast[float](self.pop())))
|
|
of NegateFloat32:
|
|
self.push(cast[uint64](-cast[float32](self.pop())))
|
|
of Add:
|
|
self.push(self.pop() + self.pop())
|
|
of Subtract:
|
|
self.push(self.pop() - self.pop())
|
|
of Multiply:
|
|
self.push(self.pop() * self.pop())
|
|
of Divide:
|
|
self.push(self.pop() div self.pop())
|
|
of SignedDivide:
|
|
self.push(uint64(int64(self.pop()) div int64(self.pop())))
|
|
of AddFloat64:
|
|
self.push(cast[uint64](cast[float](self.pop()) + cast[float](self.pop())))
|
|
of SubtractFloat64:
|
|
self.push(cast[uint64](cast[float](self.pop()) - cast[float](self.pop())))
|
|
of MultiplyFloat64:
|
|
self.push(cast[uint64](cast[float](self.pop()) * cast[float](self.pop())))
|
|
of DivideFloat64:
|
|
self.push(cast[uint64](cast[float](self.pop()) / cast[float](self.pop())))
|
|
of AddFloat32:
|
|
self.push(cast[uint64](cast[float32](self.pop()) + cast[float32](self.pop())))
|
|
of SubtractFloat32:
|
|
self.push(cast[uint64](cast[float32](self.pop()) - cast[float32](self.pop())))
|
|
of MultiplyFloat32:
|
|
self.push(cast[uint64](cast[float32](self.pop()) * cast[float32](self.pop())))
|
|
of DivideFloat32:
|
|
self.push(cast[uint64](cast[float32](self.pop()) / cast[float32](self.pop())))
|
|
of Pow:
|
|
self.push(uint64(self.pop() ^ self.pop()))
|
|
of SignedPow:
|
|
self.push(uint64(int64(self.pop()) ^ int64(self.pop())))
|
|
of PowFloat64:
|
|
self.push(cast[uint64](pow(cast[float](self.pop()), cast[float](self.pop()))))
|
|
of PowFloat32:
|
|
self.push(cast[uint64](pow(cast[float](self.pop()), cast[float](self.pop()))))
|
|
of Mod:
|
|
self.push(uint64(self.pop() mod self.pop()))
|
|
of SignedMod:
|
|
self.push(uint64(int64(self.pop()) mod int64(self.pop())))
|
|
of ModFloat64:
|
|
self.push(cast[uint64](floorMod(cast[float](self.pop()), cast[float](self.pop()))))
|
|
of ModFloat32:
|
|
self.push(cast[uint64](floorMod(cast[float](self.pop()), cast[float](self.pop()))))
|
|
of LShift:
|
|
self.push(self.pop() shl self.pop())
|
|
of RShift:
|
|
self.push(self.pop() shr self.pop())
|
|
of Xor:
|
|
self.push(self.pop() xor self.pop())
|
|
of Not:
|
|
self.push(not self.pop())
|
|
of And:
|
|
self.push(self.pop() and self.pop())
|
|
# Comparison opcodes
|
|
of Equal:
|
|
self.push(self.getBool(self.pop() == self.pop()))
|
|
of NotEqual:
|
|
self.push(self.getBool(self.pop() != self.pop()))
|
|
of GreaterThan:
|
|
self.push(self.getBool(self.pop() !> self.pop()))
|
|
of LessThan:
|
|
self.push(self.getBool(self.pop() < self.pop()))
|
|
of GreaterOrEqual:
|
|
self.push(self.getBool(self.pop() !>= self.pop()))
|
|
of LessOrEqual:
|
|
self.push(self.getBool(self.pop() <= self.pop()))
|
|
# Print opcodes
|
|
of PrintInt64:
|
|
echo cast[int64](self.pop())
|
|
of PrintUInt64:
|
|
echo self.pop()
|
|
of PrintInt32:
|
|
echo cast[int32](self.pop())
|
|
of PrintUInt32:
|
|
echo uint32(self.pop())
|
|
of PrintInt16:
|
|
echo cast[int16](self.pop())
|
|
of PrintUInt16:
|
|
echo uint16(self.pop())
|
|
of PrintInt8:
|
|
echo cast[int8](self.pop())
|
|
of PrintUInt8:
|
|
echo uint8(self.pop())
|
|
of PrintFloat32:
|
|
echo cast[float32](self.pop())
|
|
of PrintFloat64:
|
|
echo cast[float](self.pop())
|
|
of PrintHex:
|
|
echo "0x" & self.pop().toHex().strip(chars={'0'})
|
|
of PrintBool:
|
|
if self.pop().bool:
|
|
echo "true"
|
|
else:
|
|
echo "false"
|
|
of PrintInf:
|
|
if self.pop() == 0x3:
|
|
echo "inf"
|
|
else:
|
|
echo "-inf"
|
|
of PrintNan:
|
|
echo "nan"
|
|
of PrintString:
|
|
let s = cast[ptr HeapObject](self.pop())
|
|
for i in 0..<s.len:
|
|
stdout.write(s.str[i])
|
|
stdout.write("\n")
|
|
of SysClock64:
|
|
self.push(cast[uint64](getMonoTime().ticks.float() / 1_000_000_000))
|
|
of LogicalNot:
|
|
self.push(uint64(not self.pop().bool))
|
|
else:
|
|
discard
|
|
|
|
|
|
proc run*(self: var PeonVM, chunk: Chunk, breakpoints: seq[uint64] = @[]) =
|
|
## Executes a piece of Peon bytecode
|
|
self.chunk = chunk
|
|
self.frames = @[]
|
|
self.calls = @[]
|
|
self.operands = @[]
|
|
self.breakpoints = breakpoints
|
|
self.results = @[]
|
|
self.ip = 0
|
|
self.lastDebugCommand = ""
|
|
try:
|
|
self.dispatch()
|
|
except NilAccessDefect:
|
|
stderr.writeLine("Memory Access Violation: SIGSEGV")
|
|
quit(1)
|
|
# We clean up after ourselves!
|
|
self.collect()
|
|
|
|
|
|
{.pop.}
|