50 lines
1.5 KiB
Text
50 lines
1.5 KiB
Text
/-
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Copyright (c) 2019 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Leonardo de Moura
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-/
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prelude
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import init.lean.compiler.ir
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namespace Lean
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namespace IR
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partial def reshapeWithoutDeadAux : Array FnBody → FnBody → IndexSet → FnBody
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| bs b used :=
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if bs.isEmpty then b
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else
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let curr := bs.back in
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let bs := bs.pop in
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let keep (_ : Unit) :=
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let used := curr.collectFreeVars used in
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let b := curr.setBody b in
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reshapeWithoutDeadAux bs b used in
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let keepIfUsed (vidx : Index) :=
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if used.contains vidx then keep ()
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else reshapeWithoutDeadAux bs b used in
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match curr with
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| FnBody.vdecl x _ _ _ := keepIfUsed x.idx
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| FnBody.jdecl j _ _ _ _ := keepIfUsed j.idx
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| _ := keep ()
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def reshapeWithoutDead (bs : Array FnBody) (term : FnBody) : FnBody :=
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reshapeWithoutDeadAux bs term term.freeVars
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partial def FnBody.elimDead : FnBody → FnBody
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| b :=
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let (bs, term) := b.flatten in
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let bs := modifyJPs bs FnBody.elimDead in
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let term := match term with
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| FnBody.case tid x alts :=
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let alts := alts.hmap $ λ alt, alt.modifyBody FnBody.elimDead in
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FnBody.case tid x alts
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| other := other in
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reshapeWithoutDead bs term
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/-- Eliminate dead let-declarations and join points -/
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def Decl.elimDead : Decl → Decl
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| (Decl.fdecl f xs t b) := Decl.fdecl f xs t b.elimDead
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| other := other
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end IR
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end Lean
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