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1e6187c4f4
Andy some time ago already created the new API but didn't go through and update the old occurences. I did that in this PR and then deprecated the old API. The tree is clean, so I could just remove it, but I decided to be nicer to downstream people by deprecating it first.
69 lines
2.4 KiB
C++
69 lines
2.4 KiB
C++
//===--- BorrowScopeOpts.cpp ----------------------------------------------===//
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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 - 2020 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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///
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/// \file
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///
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/// Optimizations that attempt to simplify and or eliminate borrow scopes. Today
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/// we only eliminate scopes, but we could also eliminate redundant scopes by
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/// converting struct_extract operations to use destructure operations.
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///
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//===----------------------------------------------------------------------===//
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#include "Context.h"
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#include "SemanticARCOptVisitor.h"
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using namespace swift;
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using namespace swift::semanticarc;
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bool SemanticARCOptVisitor::visitBeginBorrowInst(BeginBorrowInst *bbi) {
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// Quickly check if we are supposed to perform this transformation.
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if (!ctx.shouldPerform(ARCTransformKind::RedundantBorrowScopeElimPeephole))
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return false;
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// Non-redundant, lexical borrow scopes must remain in order to ensure that
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// value lifetimes are not observably shortened.
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if (bbi->isLexical() && !isNestedLexicalBeginBorrow(bbi)) {
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return false;
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}
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auto kind = bbi->getOperand()->getOwnershipKind();
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SmallVector<EndBorrowInst *, 16> endBorrows;
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for (auto *op : bbi->getUses()) {
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if (!op->isLifetimeEnding()) {
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// Make sure that this operand can accept our arguments kind.
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if (op->canAcceptKind(kind))
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continue;
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return false;
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}
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// Otherwise, this borrow is being consumed. See if our consuming inst is an
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// end_borrow. If it isn't, then return false, this scope is
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// needed. Otherwise, add the end_borrow to our list of end borrows.
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auto *ebi = dyn_cast<EndBorrowInst>(op->getUser());
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if (!ebi) {
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return false;
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}
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endBorrows.push_back(ebi);
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}
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// At this point, we know that the begin_borrow's operand can be
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// used as an argument to all non-end borrow uses. Eliminate the
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// begin borrow and end borrows.
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while (!endBorrows.empty()) {
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auto *ebi = endBorrows.pop_back_val();
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eraseInstruction(ebi);
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}
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eraseAndRAUWSingleValueInstruction(bbi, bbi->getOperand());
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return true;
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}
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