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Cleanup and improvements regarding sparse bit
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- Remove remainders from an earlier refactoring (local variable `_isDataBoundByPC` is not used)
  - The check for this variable in UserRuntimeZero was thus always false
  - However, calls to join (label groups) are already put under a conditional checking the sparse bit in the Stack2JS phase
  - Also `wrap_block_rhs` seems to already only occour under such a conditional generated by Stack2JS, so that the blocking label is only updated when the sparse bit is not set. The function wrap_block_rhs thus becomes redundant, as it only returns its argument.
- Make code less redundant
- Use consistent naming: use "sparse bit" in all places, instead of "bound slot" etc.
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@felixwiemuth
felixwiemuth committed Sep 7, 2024
1 parent b7e6532 commit 4260d0b
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113 changes: 58 additions & 55 deletions compiler/src/Stack2JS.hs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -92,9 +92,9 @@ addLibs xs = vcat (map addOneLib xs)

data TheState = TheState { freshCounter :: Integer
, frameSize :: Int
, boundSlot :: Int
, consts :: Raw.Consts
, stHFN :: IR.HFN }
, sparseSlot :: Int
, consts :: Raw.Consts
, stHFN :: IR.HFN }

type RetKontText = PP.Doc

Expand All @@ -103,7 +103,7 @@ type W = RWS Bool ([LibAccess], [Basics.AtomName], [RetKontText]) TheState

initState = TheState { freshCounter = 0
, frameSize = error "frameSize should not be accessed yet"
, boundSlot = error "boundSlot should not be accessed yet"
, sparseSlot = error "sparseSlot should not be accessed yet"
, consts = error "consts should not be accessed yet"
, stHFN = error "stHFN should not be accessed yet"
}
Expand Down Expand Up @@ -207,22 +207,21 @@ constsToJS consts =
instance ToJS FunDef where
toJS fdef@(FunDef hfn stacksize consts bb irfdef) = do
{--
| | | ... | <bound_slot> |
| | | ... | <sparse slot> |
^ ^
| |
SP stacksize
--}
let _frameSize = stacksize + 1

modify (\s -> s { frameSize = _frameSize, boundSlot = stacksize, stHFN = hfn, consts = consts } ) -- + 1 for the _data_bound_by_pc flag; 2021-03-17; AA
let lits = constsToJS consts
modify (\s -> s { frameSize = _frameSize, sparseSlot = stacksize, stHFN = hfn, consts = consts } ) -- + 1 for the sparse flag; 2021-03-17; AA
let lits = constsToJS consts
jj <- toJS bb
debug <- ask
let (irdeps, libdeps, atomdeps ) = IR.ppDeps irfdef
b_slot_index = text "_SP + " PP.<> (PP.int stacksize)
data_bound_by_pc_slot = text "_STACK[ " PP.<> b_slot_index PP.<> "]"

let (irdeps, libdeps, atomdeps ) = IR.ppDeps irfdef
sparseSlotIdxPP <- ppSparseSlotIdx

return $
vcat [text "this." PP.<> ppId hfn <+> text "=" <+> ppArgs ["$env"] <+> text "=> {"
, if debug then nest 2 $ text "rt.debug" <+> (PP.parens . PP.quotes. ppId) hfn
Expand All @@ -232,8 +231,11 @@ instance ToJS FunDef where
"let _STACK = _T.callStack",
"let _SP = _T._sp",
"let _SP_OLD",
data_bound_by_pc_slot <+> " = _T.checkDataBoundsEntry($env.__dataLevel)",
"_T.boundSlot = " <+> b_slot_index,
-- Update sparse bit at function entry:
-- Check whether environment's data level, and the label and data level of R0 are bound by PC.
-- Requires sparseSlot to be updated first.
"_T.sparseSlot = " <+> sparseSlotIdxPP,
"_T.updateSparseBitOnEntry($env.__dataLevel)",
lits,
jj]
, text "}"
Expand Down Expand Up @@ -285,7 +287,7 @@ binOpToJS = \case
Neq -> "rt.neq"
Concat -> "+"
HasField -> "rt.hasField"
LatticeJoin -> "rt.join"
LatticeJoin -> "rt.raw_join"
-- No RT operations (should be moved to a different datatype)
RaisedTo -> error "Not a runtime operation"
-- Not yet implemented in IR2Raw
Expand Down Expand Up @@ -350,25 +352,22 @@ ir2js (MkFunClosures envBindings funBindings) = do
where ppEnvIds env ls =
vcat (
(map (\(a,b) -> semi $ (ppId env) PP.<> text "." PP.<> (ppId a) <+> text "=" <+> ppId b ) ls)
++
[ppId env PP.<> text ".__dataLevel = " <+> (jsFunCall "rt.join" (map (\(_, b) -> ppId b <> text ".dataLevel") ls )) ]
++
[ppId env PP.<> text ".__dataLevel = " <+> jsFunCall (text $ binOpToJS Basics.LatticeJoin) (map (\(_, b) -> ppId b <> text ".dataLevel") ls ) ]
)
hsepc ls = semi $ PP.hsep (PP.punctuate (text ",") ls)


ir2js (SetState c x) =
let rhs = case c of MonBlock -> ppFunCall "rt.wrap_block_rhs" [ppId x]
_ -> ppId x

in return $ semi $ monStateToJs c <+> "=" <+> rhs
ir2js (SetState c x) = return $ semi $ monStateToJs c <+> "=" <+> ppId x

ir2js (RTAssertion a) = return $ ppRTAssertionCode jsFunCall a

ir2js (LabelGroup ii) = do
ii' <- mapM ppLevelOp ii
b_slot <- data_bounded_by_pc_slot
ir2js (LabelGroup ii) = do
ii' <- mapM ppLevelOp ii
sparseSlot <- ppSparseSlot
return $ vcat $
[ "if (!" <+> b_slot <+> ") {"
[ -- "if (! _T.getSparseBit()) {" -- Alternative, but involves extra call to RT
"if (!" <+> sparseSlot <+> ") {"
, nest 2 (vcat ii')
, text "}"
]
Expand All @@ -391,30 +390,33 @@ ir2js InvalidateSparseBit = return $
{-- TERMINATORS --}


tr2js (Call bb bb2) = do
_frameSize <- frameSize <$> get
_boundSlot <- boundSlot <$> get
_consts <- consts <$> get
modify (\s -> s {frameSize = 0, boundSlot = _boundSlot - _frameSize - 5})
tr2js (Call bb bb2) = do
_frameSize <- gets frameSize
_sparseSlot <- gets sparseSlot
_consts <- gets consts
modify (\s -> s {frameSize = 0, sparseSlot = _sparseSlot - _frameSize - 5})
-- AA; 2021-04-24; Because
js <- toJS bb
modify (\s -> s { frameSize = _frameSize, boundSlot = _boundSlot })
modify (\s -> s { frameSize = _frameSize, sparseSlot = _sparseSlot })
-- TODO: AA; 2021-04-24; we should really be using a reader monad here for frame size
-- #codedebt
js2 <- toJS bb2
kname <- freshKontName
b_slot <- data_bounded_by_pc_slot
b_slot_index <- b_slot_absolute_index
let jsKont =
vcat ["this." PP.<> ppId kname <+> text "= () => {",
nest 2 $
vcat [
kname <- freshKontName
sparseSlotIdxPP <- ppSparseSlotIdx
let jsKont =
vcat ["this." PP.<> ppId kname <+> text "= () => {",
nest 2 $
vcat [
"let _T = rt.runtime.$t",
"let _STACK = _T.callStack",
"let _SP = _T._sp",
-- TODO Do we need this? It seems to be only used zero or one time in the generated places.
-- So we could instead just use the let where it is actually set.
"let _SP_OLD",
b_slot <+> "= _T.checkDataBounds(" <+> b_slot <+> ")" ,
"_T.boundSlot =" <+> b_slot_index ,
-- Check data bound at return point (could have received labelled information or raised).
-- Requires sparseSlot to be updated first.
"_T.sparseSlot =" <+> sparseSlotIdxPP,
"_T.updateSparseBitOnReturn()",
constsToJS _consts , -- 2021-05-18; TODO: optimize by including only the _used_ constants
js2
],
Expand Down Expand Up @@ -479,15 +481,16 @@ monStateToJs c =
R0_TLev -> text "r0_tlev"


data_bounded_by_pc_slot :: W PP.Doc
data_bounded_by_pc_slot = do
_b <- boundSlot <$> get
return $ text "_STACK[ _SP + " PP.<> (text (show (_b))) PP.<> text "]"
ppSparseSlotIdx :: W PP.Doc
ppSparseSlotIdx = do
s <- gets sparseSlot
return $ text "_SP + " PP.<+> PP.int s

ppSparseSlot :: W PP.Doc
ppSparseSlot = do
idx <- ppSparseSlotIdx
return $ text "_STACK[ " PP.<> idx PP.<> text "]"

b_slot_absolute_index :: W PP.Doc
b_slot_absolute_index = do
_b <- boundSlot<$> get
return $ text "_SP +" PP.<+> (PP.int _b)
-----------------------------------------------------------


Expand Down Expand Up @@ -563,16 +566,16 @@ jsFunCall a b = semi $ ppFunCall a b


freshEnvVar :: W VarName
freshEnvVar = do
k <- freshCounter <$> get
modify (\s -> s { freshCounter = k + 1 } )
freshEnvVar = do
k <- gets freshCounter
modify (\s -> s { freshCounter = k + 1 } )
return $ VN $ "$$$env" ++ (show k)


freshKontName :: W VarName
freshKontName = do
j <- freshCounter <$> get
HFN s <- stHFN <$> get
freshKontName = do
j <- gets freshCounter
HFN s <- gets stHFN
modify (\s -> s { freshCounter = j + 1})
return $ VN $ "$$$" ++ s ++ "$$$kont" ++ (show j)

Expand Down
76 changes: 36 additions & 40 deletions rt/src/Thread.mts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -212,9 +212,7 @@ export class Thread {
next : () => any;
callStack : any []
_sp : number;
boundSlot : number;

_isDataBoundByPC: boolean = false;
sparseSlot : number; // slot on the stack holding the sparse bit (whether data is bounded by PC)

processDebuggingName: string;

Expand Down Expand Up @@ -250,7 +248,7 @@ export class Thread {
---> stack growth direction --->
|---------+-------------------+--------------+-----------------------------+---------------+-------------------------+--------------------|
| sp_prev | pc at return site | ret callback | mclear at the time of entry | branching bit | [escaping locals] | bound_slot |
| sp_prev | pc at return site | ret callback | mclear at the time of entry | branching bit | [escaping locals] | sparse slot |
|---------+-------------------+--------------+-----------------------------+---------------+-------------------------+--------------------|
| sp - 5 | sp - 4 | sp - 3 | sp - 2 | sp - 1 | sp ... (sp + framesize) | sp + framesize + 1 |
Expand Down Expand Up @@ -329,7 +327,7 @@ export class Thread {

showStack () {
console.log ("======== SHOW STACK ========= ")
console.log (`sp = ${this._sp} boundslot = ${this.boundSlot}`)
console.log (`sp = ${this._sp} sparseSlot = ${this.sparseSlot}`)
let j = this._sp - 1
let stack = this.callStack
while ( j > 0) {
Expand Down Expand Up @@ -365,46 +363,45 @@ export class Thread {
return f;
}

getSparseBit() {
return this.callStack[this.sparseSlot]
}

invalidateSparseBit () {
this.callStack[this.boundSlot] = false;
invalidateSparseBit() {
this.callStack[this.sparseSlot] = false;
}

// Check whether the label of R0 (argument), the data level of R0 and the given one are bound by PC.
checkDataBoundsEntry (x: Level) {
private setSparseBit(b: boolean) {
this.callStack[this.sparseSlot] = b;
}

/**
* Check whether the label of R0 (argument), the data level of R0 and the given label are bound by PC.
*/
updateSparseBitOnEntry(x: Level) {
const _pc = this.pc
let y =
this.setSparseBit(
flowsTo(this.r0_lev, _pc)
&&
flowsTo (x, _pc)
&& (this.r0_val._troupeType == undefined
? true
: flowsTo (this.r0_val.dataLevel, _pc)
)


// this._isDataBoundByPC = y;
return y;
}

// Check whether the label of R0 (return value) and the data level of R0 are bound by PC.
// Return false if x is false.
// TODO Better check x directly and do not call this function if false (now that _isDataBoundByPC is not updated).
checkDataBounds (x: boolean) {
const _pc = this.pc
let y =
x? flowsTo(this.r0_lev, _pc)
&& (this.r0_val._troupeType == undefined
? true
: flowsTo (this.r0_val.dataLevel, _pc)
)
: false

// this._isDataBoundByPC = y;
return y;
&& flowsTo(x, _pc)
// Only non-basic types (_troupeType is defined) have a data-level
&& (this.r0_val._troupeType == undefined || flowsTo (this.r0_val.dataLevel, _pc))
)
}


/**
* If the sparse bit is set, check whether it is still valid for the returned value:
* Check whether the label of R0 (return value) and the data level of R0 are bound by PC.
*/
updateSparseBitOnReturn() {
const _pc = this.pc
if(this.getSparseBit()) { // only invalidating sparse bit
this.setSparseBit(
flowsTo(this.r0_lev, _pc)
// Only non-basic types (_troupeType is defined) have a data-level
&& (this.r0_val._troupeType == undefined || flowsTo (this.r0_val.dataLevel, _pc))
)
}
}


runNext (theFun, args, nm) {
Expand Down Expand Up @@ -619,8 +616,7 @@ export class Thread {


blockdeclto (auth, bl_to = this.pc) {
let is_bounded_by_pc = flowsTo (this.pc, bl_to);
if (!is_bounded_by_pc) {
if (! flowsTo (this.pc, bl_to)) {
this.threadError ("The provided target blocking level is lower than the current pc\n" +
` | the current pc: ${this.pc.stringRep()}\n` +
` | target blocking level: ${bl_to.stringRep()}`)
Expand Down
15 changes: 2 additions & 13 deletions rt/src/builtins/UserRuntimeZero.mts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -92,22 +92,11 @@ export class UserRuntimeZero {
this.runtime.ret (x)
}

join (...xs) {
if (this.runtime.$t._isDataBoundByPC) {
return this.runtime.$t.pc
}
// SimpleRT
raw_join(...xs) : Level {
return lub.apply (null, xs)
}

wrap_block_rhs (x) {
if (this.runtime.$t._isDataBoundByPC) {
return this.runtime.$t.bl
} else {
return x;
}

}

// SpecialRT
raw_invalidateSparseBit() {
this.runtime.$t.invalidateSparseBit()
Expand Down

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