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first implementation of write tracking and escape analysis; still disabled

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This commit is contained in:
Araq 2015-08-31 11:09:12 +02:00
commit e733debec7
5 changed files with 319 additions and 21 deletions
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46
compiler/sempass2.nim
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@ -9,7 +9,7 @@
import
intsets, ast, astalgo, msgs, renderer, magicsys, types, idents, trees,
wordrecg, strutils, options, guards
wordrecg, strutils, options, guards, writetracking
# Second semantic checking pass over the AST. Necessary because the old
# way had some inherent problems. Performs:
@ -17,7 +17,7 @@ import
# * effect+exception tracking
# * "usage before definition" checking
# * checks for invalid usages of compiletime magics (not implemented)
# * checks for invalid usages of PNimNode (not implemented)
# * checks for invalid usages of NimNode (not implemented)
# * later: will do an escape analysis for closures at least
# Predefined effects:
@ -29,21 +29,6 @@ import
# --> a TR macro can annotate the proc with user defined annotations
# --> the effect system can access these
# Load&Store analysis is performed on *paths*. A path is an access like
# obj.x.y[i].z; splitting paths up causes some problems:
#
# var x = obj.x
# var z = x.y[i].z
#
# Alias analysis is affected by this too! A good solution is *type splitting*:
# T becomes T1 and T2 if it's known that T1 and T2 can't alias.
#
# An aliasing problem and a race condition are effectively the same problem.
# Type based alias analysis is nice but not sufficient; especially splitting
# an array and filling it in parallel should be supported but is not easily
# done: It essentially requires a built-in 'indexSplit' operation and dependent
# typing.
# ------------------------ exception and tag tracking -------------------------
discard """
@ -438,17 +423,41 @@ proc documentEffect(n, x: PNode, effectType: TSpecialWord, idx: int): PNode =
result = newNode(nkExprColonExpr, n.info, @[
newIdentNode(getIdent(specialWords[effectType]), n.info), effects])
proc documentWriteEffect(n: PNode; flag: TSymFlag; pragmaName: string): PNode =
let s = n.sons[namePos].sym
let params = s.typ.n
var effects = newNodeI(nkBracket, n.info)
for i in 1 ..< params.len:
if params[i].kind == nkSym and flag in params[i].sym.flags:
effects.add params[i]
if effects.len > 0:
result = newNode(nkExprColonExpr, n.info, @[
newIdentNode(getIdent(pragmaName), n.info), effects])
proc documentNewEffect(n: PNode): PNode =
let s = n.sons[namePos].sym
if tfReturnsNew in s.typ.flags:
result = newIdentNode(getIdent("new"), n.info)
proc documentRaises*(n: PNode) =
if n.sons[namePos].kind != nkSym: return
let pragmas = n.sons[pragmasPos]
let p1 = documentEffect(n, pragmas, wRaises, exceptionEffects)
let p2 = documentEffect(n, pragmas, wTags, tagEffects)
let p3 = documentWriteEffect(n, sfWrittenTo, "writes")
let p4 = documentNewEffect(n)
let p5 = documentWriteEffect(n, sfEscapes, "escapes")
if p1 != nil or p2 != nil:
if p1 != nil or p2 != nil or p3 != nil or p4 != nil or p5 != nil:
if pragmas.kind == nkEmpty:
n.sons[pragmasPos] = newNodeI(nkPragma, n.info)
if p1 != nil: n.sons[pragmasPos].add p1
if p2 != nil: n.sons[pragmasPos].add p2
if p3 != nil: n.sons[pragmasPos].add p3
if p4 != nil: n.sons[pragmasPos].add p4
if p5 != nil: n.sons[pragmasPos].add p5
template notGcSafe(t): expr = {tfGcSafe, tfNoSideEffect} * t.flags == {}
@ -900,6 +909,7 @@ proc trackProc*(s: PSym, body: PNode) =
message(s.info, warnLockLevel,
"declared lock level is $1, but real lock level is $2" %
[$s.typ.lockLevel, $t.maxLockLevel])
when useWriteTracking: trackWrites(s, body)
proc trackTopLevelStmt*(module: PSym; n: PNode) =
if n.kind in {nkPragma, nkMacroDef, nkTemplateDef, nkProcDef,