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#
#
# The Nim Compiler
# (c) Copyright 2013 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module contains the type definitions for the new evaluation engine.
## An instruction is 1-3 int32s in memory, it is a register based VM.
import ast, passes, msgs, intsets
const
byteExcess* = 128 # we use excess-K for immediates
wordExcess* = 32768
MaxLoopIterations* = 1500_000 # max iterations of all loops
type
TRegister* = range[0..255]
TDest* = range[-1 .. 255]
TInstr* = distinct uint32
TOpcode* = enum
opcEof, # end of code
opcRet, # return
opcYldYoid, # yield with no value
opcYldVal, # yield with a value
opcAsgnInt,
opcAsgnStr,
opcAsgnFloat,
opcAsgnRef,
opcAsgnComplex,
opcRegToNode,
opcNodeToReg,
opcLdArr, # a = b[c]
opcWrArr, # a[b] = c
opcLdObj, # a = b.c
opcWrObj, # a.b = c
opcAddrReg,
opcAddrNode,
opcLdDeref,
opcWrDeref,
opcWrStrIdx,
opcLdStrIdx, # a = b[c]
opcAddInt,
opcAddImmInt,
opcSubInt,
opcSubImmInt,
opcLenSeq,
opcLenStr,
opcIncl, opcInclRange, opcExcl, opcCard, opcMulInt, opcDivInt, opcModInt,
opcAddFloat, opcSubFloat, opcMulFloat, opcDivFloat, opcShrInt, opcShlInt,
opcBitandInt, opcBitorInt, opcBitxorInt, opcAddu, opcSubu, opcMulu,
opcDivu, opcModu, opcEqInt, opcLeInt, opcLtInt, opcEqFloat,
opcLeFloat, opcLtFloat, opcLeu, opcLtu, opcEqRef, opcEqNimrodNode, opcXor,
opcNot, opcUnaryMinusInt, opcUnaryMinusFloat, opcBitnotInt,
opcEqStr, opcLeStr, opcLtStr, opcEqSet, opcLeSet, opcLtSet,
opcMulSet, opcPlusSet, opcMinusSet, opcSymdiffSet, opcConcatStr,
opcContainsSet, opcRepr, opcSetLenStr, opcSetLenSeq,
opcSwap, opcIsNil, opcOf, opcIs,
opcSubStr, opcParseFloat, opcConv, opcCast,
opcQuit, opcReset,
opcNarrowS, opcNarrowU,
opcAddStrCh,
opcAddStrStr,
opcAddSeqElem,
opcRangeChck,
opcNAdd,
opcNAddMultiple,
opcNKind,
opcNIntVal,
opcNFloatVal,
opcNSymbol,
opcNIdent,
opcNGetType,
opcNStrVal,
opcNSetIntVal,
opcNSetFloatVal, opcNSetSymbol, opcNSetIdent, opcNSetType, opcNSetStrVal,
opcNNewNimNode, opcNCopyNimNode, opcNCopyNimTree, opcNDel, opcGenSym,
opcSlurp,
opcGorge,
opcParseExprToAst,
opcParseStmtToAst,
opcQueryErrorFlag,
opcNError,
opcNWarning,
opcNHint,
opcNLineInfo,
opcEqIdent,
opcStrToIdent,
opcIdentToStr,
opcEcho,
opcIndCall, # dest = call regStart, n; where regStart = fn, arg1, ...
opcIndCallAsgn, # dest = call regStart, n; where regStart = fn, arg1, ...
opcRaise,
opcNChild,
opcNSetChild,
opcCallSite,
opcNewStr,
opcTJmp, # jump Bx if A != 0
opcFJmp, # jump Bx if A == 0
opcJmp, # jump Bx
opcJmpBack, # jump Bx; resulting from a while loop
opcBranch, # branch for 'case'
opcTry,
opcExcept,
opcFinally,
opcFinallyEnd,
opcNew,
opcNewSeq,
opcLdNull, # dest = nullvalue(types[Bx])
opcLdNullReg,
opcLdConst, # dest = constants[Bx]
opcAsgnConst, # dest = copy(constants[Bx])
opcLdGlobal, # dest = globals[Bx]
opcLdGlobalAddr, # dest = addr(globals[Bx])
opcLdImmInt, # dest = immediate value
opcNBindSym,
opcSetType, # dest.typ = types[Bx]
opcTypeTrait,
opcMarshalLoad, opcMarshalStore
TBlock* = object
label*: PSym
fixups*: seq[TPosition]
TEvalMode* = enum ## reason for evaluation
emRepl, ## evaluate because in REPL mode
emConst, ## evaluate for 'const' according to spec
emOptimize, ## evaluate for optimization purposes (same as
## emConst?)
emStaticExpr, ## evaluate for enforced compile time eval
## ('static' context)
emStaticStmt ## 'static' as an expression
TSandboxFlag* = enum ## what the evaluation engine should allow
allowCast, ## allow unsafe language feature: 'cast'
allowFFI, ## allow the FFI
allowInfiniteLoops ## allow endless loops
TSandboxFlags* = set[TSandboxFlag]
TSlotKind* = enum # We try to re-use slots in a smart way to
# minimize allocations; however the VM supports arbitrary
# temporary slot usage. This is required for the parameter
# passing implementation.
slotEmpty, # slot is unused
slotFixedVar, # slot is used for a fixed var/result (requires copy then)
slotFixedLet, # slot is used for a fixed param/let
slotTempUnknown, # slot but type unknown (argument of proc call)
slotTempInt, # some temporary int
slotTempFloat, # some temporary float
slotTempStr, # some temporary string
slotTempComplex, # some complex temporary (s.node field is used)
slotTempPerm # slot is temporary but permanent (hack)
PProc* = ref object
blocks*: seq[TBlock] # blocks; temp data structure
sym*: PSym
slots*: array[TRegister, tuple[inUse: bool, kind: TSlotKind]]
maxSlots*: int
VmArgs* = object
ra*, rb*, rc*: Natural
slots*: pointer
currentException*: PNode
VmCallback* = proc (args: VmArgs) {.closure.}
PCtx* = ref TCtx
TCtx* = object of passes.TPassContext # code gen context
code*: seq[TInstr]
debug*: seq[TLineInfo] # line info for every instruction; kept separate
# to not slow down interpretation
globals*: PNode #
constants*: PNode # constant data
types*: seq[PType] # some instructions reference types (e.g. 'except')
currentExceptionA*, currentExceptionB*: PNode
exceptionInstr*: int # index of instruction that raised the exception
prc*: PProc
module*: PSym
callsite*: PNode
mode*: TEvalMode
features*: TSandboxFlags
traceActive*: bool
loopIterations*: int
comesFromHeuristic*: TLineInfo # Heuristic for better macro stack traces
callbacks*: seq[tuple[key: string, value: VmCallback]]
errorFlag*: string
TPosition* = distinct int
PEvalContext* = PCtx
proc newCtx*(module: PSym): PCtx =
PCtx(code: @[], debug: @[],
globals: newNode(nkStmtListExpr), constants: newNode(nkStmtList), types: @[],
prc: PProc(blocks: @[]), module: module, loopIterations: MaxLoopIterations,
comesFromHeuristic: unknownLineInfo(), callbacks: @[], errorFlag: "")
proc refresh*(c: PCtx, module: PSym) =
c.module = module
c.prc = PProc(blocks: @[])
c.loopIterations = MaxLoopIterations
proc registerCallback*(c: PCtx; name: string; callback: VmCallback) =
c.callbacks.add((name, callback))
const
firstABxInstr* = opcTJmp
largeInstrs* = { # instructions which use 2 int32s instead of 1:
opcSubStr, opcConv, opcCast, opcNewSeq, opcOf,
opcMarshalLoad, opcMarshalStore}
slotSomeTemp* = slotTempUnknown
relativeJumps* = {opcTJmp, opcFJmp, opcJmp, opcJmpBack}
template opcode*(x: TInstr): TOpcode {.immediate.} = TOpcode(x.uint32 and 0xff'u32)
template regA*(x: TInstr): TRegister {.immediate.} = TRegister(x.uint32 shr 8'u32 and 0xff'u32)
template regB*(x: TInstr): TRegister {.immediate.} = TRegister(x.uint32 shr 16'u32 and 0xff'u32)
template regC*(x: TInstr): TRegister {.immediate.} = TRegister(x.uint32 shr 24'u32)
template regBx*(x: TInstr): int {.immediate.} = (x.uint32 shr 16'u32).int
template jmpDiff*(x: TInstr): int {.immediate.} = regBx(x) - wordExcess
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