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preparations for a new AST transformation pass with the aim of giving us reliable destructors

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This commit is contained in:
Andreas Rumpf 2017-10-09 20:44:55 +02:00
commit cf01cb1935
2 changed files with 232 additions and 22 deletions
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62
compiler/dfa.nim
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@ -26,13 +26,19 @@
import ast, astalgo, types, intsets, tables, msgs
type
InstrKind = enum
goto, fork, def, use
Instr = object
n: PNode
case kind: InstrKind
of def, use: sym: PSym
of goto, fork: dest: int
InstrKind* = enum
goto, fork, def, use,
useWithinCall # this strange special case is used to get more
# move optimizations out of regular code
# XXX This is still overly pessimistic in
# call(let x = foo; bar(x))
Instr* = object
n*: PNode
case kind*: InstrKind
of def, use, useWithinCall: sym*: PSym
of goto, fork: dest*: int
ControlFlowGraph* = seq[Instr]
TPosition = distinct int
TBlock = object
@ -43,40 +49,42 @@ type
undef, value, valueOrUndef
Con = object
code: seq[Instr]
code: ControlFlowGraph
inCall: int
blocks: seq[TBlock]
proc debugInfo(info: TLineInfo): string =
result = info.toFilename & ":" & $info.line
proc codeListing(c: Con, result: var string, start=0; last = -1) =
proc codeListing(c: ControlFlowGraph, result: var string, start=0; last = -1) =
# for debugging purposes
# first iteration: compute all necessary labels:
var jumpTargets = initIntSet()
let last = if last < 0: c.code.len-1 else: min(last, c.code.len-1)
let last = if last < 0: c.len-1 else: min(last, c.len-1)
for i in start..last:
if c.code[i].kind in {goto, fork}:
jumpTargets.incl(i+c.code[i].dest)
if c[i].kind in {goto, fork}:
jumpTargets.incl(i+c[i].dest)
var i = start
while i <= last:
if i in jumpTargets: result.add("L" & $i & ":\n")
result.add "\t"
result.add $c.code[i].kind
result.add $c[i].kind
result.add "\t"
case c.code[i].kind
of def, use:
result.add c.code[i].sym.name.s
case c[i].kind
of def, use, useWithinCall:
result.add c[i].sym.name.s
of goto, fork:
result.add "L"
result.add c.code[i].dest+i
result.add c[i].dest+i
result.add("\t#")
result.add(debugInfo(c.code[i].n.info))
result.add(debugInfo(c[i].n.info))
result.add("\n")
inc i
if i in jumpTargets: result.add("L" & $i & ": End\n")
proc echoCfg*(c: Con; start=0; last = -1) {.deprecated.} =
proc echoCfg*(c: ControlFlowGraph; start=0; last = -1) {.deprecated.} =
## echos the ControlFlowGraph for debugging purposes.
var buf = ""
codeListing(c, buf, start, last)
echo buf
@ -243,7 +251,10 @@ proc genUse(c: var Con; n: PNode) =
nkAddr, nkHiddenAddr}:
n = n[0]
if n.kind == nkSym and n.sym.kind in InterestingSyms:
c.code.add Instr(n: n, kind: use, sym: n.sym)
if c.inCall > 0:
c.code.add Instr(n: n, kind: useWithinCall, sym: n.sym)
else:
c.code.add Instr(n: n, kind: use, sym: n.sym)
proc genDef(c: var Con; n: PNode) =
if n.kind == nkSym and n.sym.kind in InterestingSyms:
@ -253,10 +264,12 @@ proc genCall(c: var Con; n: PNode) =
gen(c, n[0])
var t = n[0].typ
if t != nil: t = t.skipTypes(abstractInst)
inc c.inCall
for i in 1..<n.len:
gen(c, n[i])
if t != nil and i < t.len and t.sons[i].kind == tyVar:
genDef(c, n[i])
dec c.inCall
proc genMagic(c: var Con; n: PNode; m: TMagic) =
case m
@ -356,7 +369,7 @@ proc dfa(code: seq[Instr]) =
var sid = -1
case code[pc].kind
of goto, fork: discard
of use:
of use, useWithinCall:
let sym = code[pc].sym
if s[pc].contains(sym.id):
localError(code[pc].n.info, "variable read before initialized: " & sym.name.s)
@ -417,5 +430,10 @@ proc dfa(code: seq[Instr]) =
proc dataflowAnalysis*(s: PSym; body: PNode) =
var c = Con(code: @[], blocks: @[])
gen(c, body)
echoCfg(c)
#echoCfg(c.code)
dfa(c.code)
proc constructCfg*(s: PSym; body: PNode): ControlFlowGraph =
## constructs a control flow graph for ``body``.
var c = Con(code: @[], blocks: @[])
shallowCopy(result, c.code)