jyapayne/Nim
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

'parallel' proves array bounds

Browse source
This commit is contained in:
Araq 2014-05-29 13:27:45 +02:00
commit 6470bd8f87
3 changed files with 107 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

30
compiler/semparallel.nim
View file

@ -59,7 +59,8 @@ type
TDirection = enum
ascending, descending
MonotonicVar = object
v: PSym
v, alias: PSym # to support the ordinary 'countup' iterator
# we need to detect aliases
lower, upper, stride: PNode
dir: TDirection
blacklisted: bool # blacklisted variables that are not monotonic
@ -83,7 +84,7 @@ proc initAnalysisCtx(): AnalysisCtx =
proc lookupSlot(c: AnalysisCtx; s: PSym): int =
for i in 0.. <c.locals.len:
if c.locals[i].v == s: return i
if c.locals[i].v == s or c.locals[i].alias == s: return i
return -1
proc getSlot(c: var AnalysisCtx; v: PSym): ptr MonotonicVar =
@ -104,6 +105,11 @@ proc gatherArgs(c: var AnalysisCtx; n: PNode) =
c.args.add root
gatherArgs(c, n[i])
proc isSingleAssignable(n: PNode): bool =
n.kind == nkSym and (let s = n.sym;
s.kind in {skTemp, skForVar, skLet} and
{sfAddrTaken, sfGlobal} * s.flags == {})
proc isLocal(n: PNode): bool =
n.kind == nkSym and (let s = n.sym;
s.kind in {skResult, skTemp, skForVar, skVar, skLet} and
@ -290,16 +296,16 @@ proc analyseCase(c: var AnalysisCtx; n: PNode) =
proc analyseIf(c: var AnalysisCtx; n: PNode) =
analyse(c, n.sons[0].sons[0])
let oldFacts = c.guards.len
addFact(c.guards, n.sons[0].sons[0])
addFact(c.guards, canon(n.sons[0].sons[0]))
analyse(c, n.sons[0].sons[1])
for i in 1.. <n.len:
let branch = n.sons[i]
setLen(c.guards, oldFacts)
for j in 0..i-1:
addFactNeg(c.guards, n.sons[j].sons[0])
addFactNeg(c.guards, canon(n.sons[j].sons[0]))
if branch.len > 1:
addFact(c.guards, branch.sons[0])
addFact(c.guards, canon(branch.sons[0]))
for i in 0 .. <branch.len:
analyse(c, branch.sons[i])
setLen(c.guards, oldFacts)
@ -307,9 +313,12 @@ proc analyseIf(c: var AnalysisCtx; n: PNode) =
proc analyse(c: var AnalysisCtx; n: PNode) =
case n.kind
of nkAsgn, nkFastAsgn:
# since we already ensure sfAddrTaken is not in s.flags, we only need to
# prevent direct assignments to the monotonic variable:
if n[0].isLocal:
if n[0].isSingleAssignable and n[1].isLocal:
let slot = c.getSlot(n[1].sym)
slot.alias = n[0].sym
elif n[0].isLocal:
# since we already ensure sfAddrTaken is not in s.flags, we only need to
# prevent direct assignments to the monotonic variable:
let slot = c.getSlot(n[0].sym)
slot.blackListed = true
invalidateFacts(c.guards, n[0])
@ -348,13 +357,13 @@ proc analyse(c: var AnalysisCtx; n: PNode) =
# loop may never execute:
let oldState = c.locals.len
let oldFacts = c.guards.len
addFact(c.guards, n.sons[0])
addFact(c.guards, canon(n.sons[0]))
analyse(c, n.sons[1])
setLen(c.locals, oldState)
setLen(c.guards, oldFacts)
# we know after the loop the negation holds:
if not hasSubnodeWith(n.sons[1], nkBreakStmt):
addFactNeg(c.guards, n.sons[0])
addFactNeg(c.guards, canon(n.sons[0]))
dec c.inLoop
of nkTypeSection, nkProcDef, nkConverterDef, nkMethodDef, nkIteratorDef,
nkMacroDef, nkTemplateDef, nkConstSection, nkPragma:
@ -429,6 +438,7 @@ proc liftParallel*(owner: PSym; n: PNode): PNode =
# - detect monotonic local integer variables
# - detect used slices
# - detect used arguments
#echo "PAR ", renderTree(n)
var a = initAnalysisCtx()
let body = n.lastSon