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https://github.com/apple/swift.git
synced 2026-10-12 14:50:47 +02:00
Joe Groff
09aeb21de3
This pass takes functions emitted in the ownership-for-trivial-values form and strips away ownership qualifiers and explicit copies or borrows of trivial values, lowering trivial values to their simplified representation as plain data.
86 lines
3.5 KiB
Swift
86 lines
3.5 KiB
Swift
//===--- TrivialOwnershipElimination.swift ----------------------------------==//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2026 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SIL
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let trivialOwnershipElimination = FunctionPass(name: "trivial-ownership-elimination") {
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(function: Function, context: FunctionPassContext) in
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eliminateTrivialOwnership(in: function, context)
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}
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private func eliminateTrivialOwnership(in function: Function, _ context: FunctionPassContext) {
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// Don't need to touch functions that are already non-OSSA, or which have
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// already had trivial ownership eliminated.
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guard function.hasOwnership, function.hasOwnershipForTrivialValues else {
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return
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}
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// Clear the ownership for trivial values flag. This way `isTrivial(in:
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// function)` tests will start revealing `true` for trivial types.
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function.set(hasOwnershipForTrivialValues: false, context)
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for block in function.blocks {
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// Remove ownership qualifiers from trivial basic block arguments.
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for arg in block.arguments where arg.type.isTrivial(in: function) {
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arg.set(ownership: .none, context)
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}
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for insn in block.instructions {
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// Change load/store/copy_addr qualifiers to trivial.
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switch insn {
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case let load as LoadInst where load.address.type.isTrivial(in: function):
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load.set(ownership: .trivial, context)
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case let store as StoreInst where store.destinationAddress.type.isTrivial(in: function):
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store.set(ownership: .trivial, context)
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case let ca as CopyAddrInst where ca.destinationAddress.type.isTrivial(in: function):
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ca.set(isTakeOfSource: false, context)
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ca.set(isInitializationOfDestination: false, context)
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// Replace load/store_borrow with trivial load/store.
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case let lb as LoadBorrowInst where lb.address.type.isTrivial(in: function):
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let builder = Builder(before: lb, context)
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let trivialLoad = builder.createLoad(fromAddress: lb.address, ownership: .trivial)
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lb.replace(with: trivialLoad, context)
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case let sb as StoreBorrowInst where sb.source.type.isTrivial(in: function):
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let builder = Builder(before: sb, context)
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builder.createStore(source: sb.source, destination: sb.destination, ownership: .trivial)
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sb.replace(with: sb.destination, context)
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// Eliminate destroy_value and destroy_addr.
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case let dv as DestroyValueInst where dv.destroyedValue.type.isTrivial(in: function):
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context.erase(instruction: dv)
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case let da as DestroyAddrInst where da.destroyedAddress.type.isTrivial(in: function):
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context.erase(instruction: da)
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// Replace `copy_value` with the original.
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case let cv as CopyValueInst where cv.fromValue.type.isTrivial(in: function):
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cv.replace(with: cv.fromValue, context)
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// Eliminate borrow scopes.
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case let bb as BeginBorrowInst where bb.borrowedValue.type.isTrivial(in: function):
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bb.replace(with: bb.borrowedValue, context)
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case let eb as EndBorrowInst where eb.borrow.type.isTrivial(in: function):
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context.erase(instruction: eb)
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// Leave other instructions alone.
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default:
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break
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}
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}
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}
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}
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