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//===--- SimplifyFixLifetime.swift ----------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import SIL
/// Canonicalize a `fix_lifetime` from an address to a `load` + `fix_lifetime`:
/// ```
/// %1 = alloc_stack $T
/// ...
/// fix_lifetime %1
/// ```
/// ->
/// ```
/// %1 = alloc_stack $T
/// ...
/// %2 = load %1
/// fix_lifetime %2
/// ```
///
/// This transformation is done for `alloc_stack` and `store_borrow` (which always has an `alloc_stack`
/// operand).
/// The benefit of this transformation is that it enables other optimizations, like mem2reg.
///
extension FixLifetimeInst : Simplifiable, SILCombineSimplifiable {
func simplify(_ context: SimplifyContext) {
let opValue = operand.value
guard opValue is AllocStackInst || opValue is StoreBorrowInst,
opValue.type.isLoadable(in: parentFunction)
else {
return
}
let builder = Builder(before: self, context)
let loadedValue: Value
if !parentFunction.hasOwnership {
loadedValue = builder.createLoad(fromAddress: opValue, ownership: .unqualified)
} else if opValue.type.isTrivial(in: parentFunction) {
loadedValue = builder.createLoad(fromAddress: opValue, ownership: .trivial)
} else {
loadedValue = builder.createLoadBorrow(fromAddress: opValue)
Builder(after: self, context).createEndBorrow(of: loadedValue)
}
operand.set(to: loadedValue, context)
}
}
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