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introduce a common superclass, SILNode. This is in preparation for allowing instructions to have multiple results. It is also a somewhat more elegant representation for instructions that have zero results. Instructions that are known to have exactly one result inherit from a class, SingleValueInstruction, that subclasses both ValueBase and SILInstruction. Some care must be taken when working with SILNode pointers and testing for equality; please see the comment on SILNode for more information. A number of SIL passes needed to be updated in order to handle this new distinction between SIL values and SIL instructions. Note that the SIL parser is now stricter about not trying to assign a result value from an instruction (like 'return' or 'strong_retain') that does not produce any.
45 lines
1.6 KiB
C++
45 lines
1.6 KiB
C++
//===--- Notifications.h - SIL Undef Value Representation -------*- C++ -*-===//
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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 - 2017 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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#ifndef SWIFT_SIL_NOTIFICATIONS_H
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#define SWIFT_SIL_NOTIFICATIONS_H
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namespace swift {
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class SILNode;
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/// A protocol (or interface) for handling value deletion notifications.
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///
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/// This class is used as a base class for any class that need to accept
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/// instruction deletion notification messages. This is used by passes and
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/// analysis that need to invalidate data structures that contain pointers.
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/// This is similar to LLVM's ValueHandle.
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struct DeleteNotificationHandler {
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DeleteNotificationHandler() { }
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virtual ~DeleteNotificationHandler() {}
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/// Handle the invalidation message for the value \p Value.
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virtual void handleDeleteNotification(SILNode *value) { }
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/// Returns True if the pass, analysis or other entity wants to receive
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/// notifications. This callback is called once when the class is being
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/// registered, and not once per notification. Entities that implement
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/// this callback should always return a constant answer (true/false).
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virtual bool needsNotifications() { return false; }
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};
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} // end swift namespace
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#endif
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