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#
#
# The Nim Compiler
# (c) Copyright 2012 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
# This module implements the passes functionality. A pass must implement the
# `TPass` interface.
import
strutils, lists, options, ast, astalgo, llstream, msgs, platform, os,
condsyms, idents, renderer, types, extccomp, math, magicsys, nversion,
nimsets, syntaxes, times, rodread, idgen
type
TPassContext* = object of RootObj # the pass's context
fromCache*: bool # true if created by "openCached"
PPassContext* = ref TPassContext
TPassOpen* = proc (module: PSym): PPassContext {.nimcall.}
TPassOpenCached* =
proc (module: PSym, rd: PRodReader): PPassContext {.nimcall.}
TPassClose* = proc (p: PPassContext, n: PNode): PNode {.nimcall.}
TPassProcess* = proc (p: PPassContext, topLevelStmt: PNode): PNode {.nimcall.}
TPass* = tuple[open: TPassOpen, openCached: TPassOpenCached,
process: TPassProcess, close: TPassClose]
TPassData* = tuple[input: PNode, closeOutput: PNode]
TPasses* = openArray[TPass]
# a pass is a tuple of procedure vars ``TPass.close`` may produce additional
# nodes. These are passed to the other close procedures.
# This mechanism used to be used for the instantiation of generics.
proc makePass*(open: TPassOpen = nil,
openCached: TPassOpenCached = nil,
process: TPassProcess = nil,
close: TPassClose = nil): TPass =
result.open = open
result.openCached = openCached
result.close = close
result.process = process
# This implements a memory preserving scheme: Top level statements are
# processed in a pipeline. The compiler never looks at a whole module
# any longer. However, this is simple to change, as new passes may perform
# whole program optimizations. For now, we avoid it to save a lot of memory.
proc processModule*(module: PSym, stream: PLLStream, rd: PRodReader)
# the semantic checker needs these:
var
gImportModule*: proc (m: PSym, fileIdx: int32): PSym {.nimcall.}
gIncludeFile*: proc (m: PSym, fileIdx: int32): PNode {.nimcall.}
# implementation
proc skipCodegen*(n: PNode): bool {.inline.} =
# can be used by codegen passes to determine whether they should do
# something with `n`. Currently, this ignores `n` and uses the global
# error count instead.
result = msgs.gErrorCounter > 0
proc astNeeded*(s: PSym): bool =
# The ``rodwrite`` module uses this to determine if the body of a proc
# needs to be stored. The passes manager frees s.sons[codePos] when
# appropriate to free the procedure body's memory. This is important
# to keep memory usage down.
if (s.kind in {skMethod, skProc}) and
({sfCompilerProc, sfCompileTime} * s.flags == {}) and
(s.typ.callConv != ccInline) and
(s.ast.sons[genericParamsPos].kind == nkEmpty):
result = false
# XXX this doesn't really make sense with excessive CTFE
else:
result = true
const
maxPasses = 10
type
TPassContextArray = array[0..maxPasses - 1, PPassContext]
var
gPasses: array[0..maxPasses - 1, TPass]
gPassesLen*: int
proc clearPasses* =
gPassesLen = 0
proc registerPass*(p: TPass) =
gPasses[gPassesLen] = p
inc(gPassesLen)
proc carryPass*(p: TPass, module: PSym, m: TPassData): TPassData =
var c = p.open(module)
result.input = p.process(c, m.input)
result.closeOutput = if p.close != nil: p.close(c, m.closeOutput)
else: m.closeOutput
proc carryPasses*(nodes: PNode, module: PSym, passes: TPasses) =
var passdata: TPassData
passdata.input = nodes
for pass in passes:
passdata = carryPass(pass, module, passdata)
proc openPasses(a: var TPassContextArray, module: PSym) =
for i in countup(0, gPassesLen - 1):
if not isNil(gPasses[i].open):
a[i] = gPasses[i].open(module)
else: a[i] = nil
proc openPassesCached(a: var TPassContextArray, module: PSym, rd: PRodReader) =
for i in countup(0, gPassesLen - 1):
if not isNil(gPasses[i].openCached):
a[i] = gPasses[i].openCached(module, rd)
if a[i] != nil:
a[i].fromCache = true
else:
a[i] = nil
proc closePasses(a: var TPassContextArray) =
var m: PNode = nil
for i in countup(0, gPassesLen - 1):
if not isNil(gPasses[i].close): m = gPasses[i].close(a[i], m)
a[i] = nil # free the memory here
proc processTopLevelStmt(n: PNode, a: var TPassContextArray): bool =
# this implements the code transformation pipeline
var m = n
for i in countup(0, gPassesLen - 1):
if not isNil(gPasses[i].process):
m = gPasses[i].process(a[i], m)
if isNil(m): return false
result = true
proc processTopLevelStmtCached(n: PNode, a: var TPassContextArray) =
# this implements the code transformation pipeline
var m = n
for i in countup(0, gPassesLen - 1):
if not isNil(gPasses[i].openCached): m = gPasses[i].process(a[i], m)
proc closePassesCached(a: var TPassContextArray) =
var m: PNode = nil
for i in countup(0, gPassesLen - 1):
if not isNil(gPasses[i].openCached) and not isNil(gPasses[i].close):
m = gPasses[i].close(a[i], m)
a[i] = nil # free the memory here
proc processImplicits(implicits: seq[string], nodeKind: TNodeKind,
a: var TPassContextArray) =
for module in items(implicits):
var importStmt = newNodeI(nodeKind, gCmdLineInfo)
var str = newStrNode(nkStrLit, module)
str.info = gCmdLineInfo
importStmt.addSon str
if not processTopLevelStmt(importStmt, a): break
proc processModule(module: PSym, stream: PLLStream, rd: PRodReader) =
var
p: TParsers
a: TPassContextArray
s: PLLStream
fileIdx = module.fileIdx
if rd == nil:
openPasses(a, module)
if stream == nil:
let filename = fileIdx.toFullPathConsiderDirty
s = llStreamOpen(filename, fmRead)
if s == nil:
rawMessage(errCannotOpenFile, filename)
return
else:
s = stream
while true:
openParsers(p, fileIdx, s)
if sfSystemModule notin module.flags:
# XXX what about caching? no processing then? what if I change the
# modules to include between compilation runs? we'd need to track that
# in ROD files. I think we should enable this feature only
# for the interactive mode.
processImplicits implicitImports, nkImportStmt, a
processImplicits implicitIncludes, nkIncludeStmt, a
while true:
var n = parseTopLevelStmt(p)
if n.kind == nkEmpty: break
if not processTopLevelStmt(n, a): break
closeParsers(p)
if s.kind != llsStdIn: break
closePasses(a)
# id synchronization point for more consistent code generation:
idSynchronizationPoint(1000)
else:
openPassesCached(a, module, rd)
var n = loadInitSection(rd)
for i in countup(0, sonsLen(n) - 1): processTopLevelStmtCached(n.sons[i], a)
closePassesCached(a)
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