Files
swift-mirror/lib/SIL/IR/SILUndef.cpp
Erik Eckstein 011358edd6 SIL: let SingleValueInstruction only inherit from a single SILNode.
This removes the ambiguity when casting from a SingleValueInstruction to SILNode, which makes the code simpler. E.g. the "isRepresentativeSILNode" logic is not needed anymore.
Also, it reduces the size of the most used instruction class - SingleValueInstruction - by one pointer.

Conceptually, SILInstruction is still a SILNode. But implementation-wise SILNode is not a base class of SILInstruction anymore.
Only the two sub-classes of SILInstruction - SingleValueInstruction and NonSingleValueInstruction - inherit from SILNode. SingleValueInstruction's SILNode is embedded into a ValueBase and its relative offset in the class is the same as in NonSingleValueInstruction (see SILNodeOffsetChecker).
This makes it possible to cast from a SILInstruction to a SILNode without knowing which SILInstruction sub-class it is.
Casting to SILNode cannot be done implicitly, but only with an LLVM `cast` or with SILInstruction::asSILNode(). But this is a rare case anyway.
2021-01-27 16:40:15 +01:00

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//===--- SILUndef.cpp -----------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2018 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
//
//===----------------------------------------------------------------------===//
#include "swift/SIL/SILUndef.h"
#include "swift/SIL/SILModule.h"
using namespace swift;
SILUndef::SILUndef(SILType type)
: ValueBase(ValueKind::SILUndef, type) {}
SILUndef *SILUndef::get(SILType ty, SILModule &m) {
SILUndef *&entry = m.UndefValues[ty];
if (entry == nullptr)
entry = new (m) SILUndef(ty);
return entry;
}
SILUndef *SILUndef::get(SILType ty, const SILFunction &f) {
return SILUndef::get(ty, f.getModule());
}