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[Experiment/Discussion] Erase List.iter #3662

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90 changes: 89 additions & 1 deletion src/fsharp/Optimizer.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -2567,7 +2567,21 @@ and TryInlineApplication cenv env finfo (tyargs: TType list, args: Expr list, m)

//-------------------------------------------------------------------------
// Optimize/analyze an application of a function to type and term arguments
//-------------------------------------------------------------------------
//-------------------------------------------------------------------------

and IterExpression vref cenv expr =
match expr with
| Expr.App(Expr.Val(valRef,_,_rangeIter), _, [TType_app _ as elementType], appliedParams, _rangeOuter)
when valRefEq cenv.g valRef vref ->
match appliedParams with
| [Expr.Lambda(_,None,None,[fVal],fBody,_m1,_fRetType);
source] -> Some(source, elementType, fVal, fBody)
| _ -> None
| _ -> None

and (|ListIterExpression|_|) cenv expr = IterExpression cenv.g.list_iter_vref cenv expr
and (|SeqIterExpression|_|) cenv expr = IterExpression cenv.g.seq_iter_vref cenv expr
and (|ArrayIterExpression|_|) cenv expr = IterExpression cenv.g.array_iter_vref cenv expr

and OptimizeApplication cenv env (f0, f0ty, tyargs, args, m) =
// trying to devirtualize
Expand Down Expand Up @@ -2610,6 +2624,80 @@ and OptimizeApplication cenv env (f0, f0ty, tyargs, args, m) =
// we beta-reduced, hence reoptimize
OptimizeExpr cenv env newExpr
| _ ->
match newExpr with
// Rewrite 'List.iter (fun x -> expr) s' into 'for x in s do expr'
| ListIterExpression cenv (enumerableExpr, elemTy, elemVar, bodyExpr) ->
let g = cenv.g
let enumExprTy = mkListTy g elemTy
let zeroRange = range.Zero
// copy pasted from TastOps: DetectAndOptimizeForExpression
let IndexHead = 0
let IndexTail = 1

let currentVar , currentExpr = mkMutableCompGenLocal zeroRange "current" enumExprTy
let nextVar , nextExpr = mkMutableCompGenLocal zeroRange "next" enumExprTy

let guardExpr = mkNonNullTest g zeroRange nextExpr
let headOrDefaultExpr = mkUnionCaseFieldGetUnprovenViaExprAddr (currentExpr, g.cons_ucref, [elemTy], IndexHead, zeroRange)
let tailOrNullExpr = mkUnionCaseFieldGetUnprovenViaExprAddr (currentExpr, g.cons_ucref, [elemTy], IndexTail, zeroRange)
let bodyExpr =
mkCompGenLet zeroRange elemVar headOrDefaultExpr
(mkCompGenSequential zeroRange
bodyExpr
(mkCompGenSequential zeroRange
(mkValSet zeroRange (mkLocalValRef currentVar) nextExpr)
(mkValSet zeroRange (mkLocalValRef nextVar) tailOrNullExpr)
)
)

let expr =
// let mutable current = enumerableExpr
mkLet NoSequencePointAtStickyBinding zeroRange currentVar enumerableExpr
// let mutable next = current.TailOrNull
(mkCompGenLet zeroRange nextVar tailOrNullExpr
// while nonNull next dp
(mkWhile g (NoSequencePointAtWhileLoop, WhileLoopForCompiledForEachExprMarker, guardExpr, bodyExpr, zeroRange)))

OptimizeExpr cenv env expr


// Rewrite 'Seq.iter (fun x -> expr) s' into 'for x in s do expr'
| SeqIterExpression cenv _ when false ->
failwith "not implemented"
//let g = cenv.g
//let enumExprTy = mkListTy g elemTy
//let zeroRange = range.Zero

//let enumExpr = enumerableExpr
//let mForLoopStart = zeroRange
//let mEnumExpr = zeroRange
//let spForLoop = NoSequencePointAtForLoop
//// ---------
//let enumerableVar, enumerableExprInVar = mkCompGenLocal mEnumExpr "inputSequence" enumExprTy
//let enumeratorVar, enumeratorExpr, _, enumElemTy, getEnumExpr, getEnumTy, guardExpr, _, currentExpr =
// TypeChecker.AnalyzeArbitraryExprAsEnumerable cenv env true mEnumExpr enumExprTy enumerableExprInVar
//let expr =
// // This compiled for must be matched EXACTLY by CompiledForEachExpr in opt.fs and creflect.fs
// mkCompGenLet mForLoopStart enumerableVar enumExpr
// (let cleanupE = TypeChecker.BuildDisposableCleanup cenv env mWholeExpr enumeratorVar
// let spBind = match spForLoop with SequencePointAtForLoop(spStart) -> SequencePointAtBinding(spStart) | NoSequencePointAtForLoop -> NoSequencePointAtStickyBinding
// (mkLet spBind mForLoopStart enumeratorVar getEnumExpr
// (mkTryFinally cenv.g
// (mkWhile cenv.g
// (NoSequencePointAtWhileLoop,
// WhileLoopForCompiledForEachExprMarker, guardExpr,
// mkCompGenLet mForLoopStart elemVar currentExpr bodyExpr,
// mForLoopStart),
// cleanupE, mForLoopStart, cenv.g.unit_ty, NoSequencePointAtTry, NoSequencePointAtFinally))))

//OptimizeExpr cenv env expr

// Rewrite 'Array.iter (fun x -> expr) s' into 'for x in s do expr'
| ArrayIterExpression cenv _ when false ->
failwith "not implemented"

| _ ->

// regular

// Determine if this application is a critical tailcall
Expand Down
8 changes: 8 additions & 0 deletions src/fsharp/TcGlobals.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -592,6 +592,9 @@ type public TcGlobals(compilingFslib: bool, ilg:ILGlobals, fslibCcu: CcuThunk, d
let v_seq_map_info = makeIntrinsicValRef(fslib_MFSeqModule_nleref, "map" , None , Some "Map" , [vara;varb], ([[varaTy --> varbTy]; [mkSeqTy varaTy]], mkSeqTy varbTy))
let v_seq_singleton_info = makeIntrinsicValRef(fslib_MFSeqModule_nleref, "singleton" , None , Some "Singleton" , [vara], ([[varaTy]], mkSeqTy varaTy))
let v_seq_empty_info = makeIntrinsicValRef(fslib_MFSeqModule_nleref, "empty" , None , Some "Empty" , [vara], ([], mkSeqTy varaTy))
let v_seq_iter_info = makeIntrinsicValRef(fslib_MFSeqModule_nleref, "iter" , None , Some "Iterate" , [varb], ([[mkSeqTy varbTy]], v_unit_ty))
let v_list_iter_info = makeIntrinsicValRef(fslib_MFListModule_nleref, "iter" , None , Some "Iterate" , [varb], ([[mkListTy varbTy]], v_unit_ty))
let v_array_iter_info = makeIntrinsicValRef(fslib_MFArrayModule_nleref, "iter" , None , Some "Iterate" , [varb], ([[mkArrayType 1 varbTy]], v_unit_ty))
let v_new_format_info = makeIntrinsicValRef(fslib_MFCore_nleref, ".ctor" , Some "PrintfFormat`5", None , [vara;varb;varc;vard;vare], ([[v_string_ty]], mkPrintfFormatTy varaTy varbTy varcTy vardTy vareTy))
let v_sprintf_info = makeIntrinsicValRef(fslib_MFExtraTopLevelOperators_nleref, "sprintf" , None , Some "PrintFormatToStringThen", [vara], ([[mk_format4_ty varaTy v_unit_ty v_string_ty v_string_ty]], varaTy))
let v_lazy_force_info =
Expand Down Expand Up @@ -1149,6 +1152,11 @@ type public TcGlobals(compilingFslib: bool, ilg:ILGlobals, fslibCcu: CcuThunk, d
member val seq_of_functions_vref = ValRefForIntrinsic v_seq_of_functions_info
member val seq_map_vref = ValRefForIntrinsic v_seq_map_info
member val seq_empty_vref = ValRefForIntrinsic v_seq_empty_info
//--
member val seq_iter_vref = ValRefForIntrinsic v_seq_iter_info
member val list_iter_vref = ValRefForIntrinsic v_list_iter_info
member val array_iter_vref = ValRefForIntrinsic v_array_iter_info
//--
member val new_format_vref = ValRefForIntrinsic v_new_format_info
member val sprintf_vref = ValRefForIntrinsic v_sprintf_info
member val unbox_vref = ValRefForIntrinsic v_unbox_info
Expand Down