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b689b1dabe
This bleeds into the implementation where "guaranteed" is used everywhere to talk about optimization of guaranteed values. We need to use mandatory to indicate we're talking about the pass pipeline.
67 lines
2.6 KiB
C++
67 lines
2.6 KiB
C++
//===--- OwnershipConversionElimination.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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#include "SemanticARC/SemanticARCOpts.h"
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#include "SemanticARCOptVisitor.h"
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#include "swift/SIL/LinearLifetimeChecker.h"
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using namespace swift;
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using namespace semanticarc;
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//===----------------------------------------------------------------------===//
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// Top Level Entrypoint
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//===----------------------------------------------------------------------===//
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bool SemanticARCOptVisitor::visitUncheckedOwnershipConversionInst(
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UncheckedOwnershipConversionInst *uoci) {
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// Return false if we are supposed to only be running guaranteed opts.
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if (ctx.onlyMandatoryOpts)
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return false;
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// Then check if we are running tests and shouldn't perform this optimization
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// since we are testing something else.
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if (!ctx.shouldPerform(ARCTransformKind::OwnershipConversionElimPeephole))
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return false;
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// Otherwise, shrink our state space so that we only consider conversions from
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// owned or guaranteed to unowned. These are always legal and it is sometimes
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// convenient to insert them to avoid forwarding issues when RAUWing
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// values. So we eliminate them here.
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if (uoci->getConversionOwnershipKind() != OwnershipKind::Unowned)
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return false;
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auto op = uoci->getOperand();
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auto opKind = op.getOwnershipKind();
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if (opKind != OwnershipKind::Owned && opKind != OwnershipKind::Guaranteed)
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return false;
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// Ok, we can perform our optimization. First go through all of the uses of
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// uoci and see if they can accept our operand without any changes and that
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// they do not consume values.
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SmallVector<Operand *, 8> newUses;
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for (auto *use : uoci->getUses()) {
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if (use->isLifetimeEnding() || !use->canAcceptKind(opKind))
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return false;
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newUses.push_back(use);
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}
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// Ok, now we need to perform our lifetime check.
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SmallVector<Operand *, 8> consumingUses(op->getConsumingUses());
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LinearLifetimeChecker checker(ctx.getDeadEndBlocks());
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if (!checker.validateLifetime(op, consumingUses, newUses))
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return false;
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// Otherwise, we can perform our rauw.
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eraseAndRAUWSingleValueInstruction(uoci, op);
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return true;
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}
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