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This adds two declarative configuration options for intrusive lists
(available for simple_ilist, iplist, and ilist). Both of these options
affect ilist_node interoperability and need to be passed both to the
node and the list. Instead of adding a new traits class, they're
specified as optional template parameters (in any order).
The two options:
1. Pass ilist_sentinel_tracking<true> or ilist_sentinel_tracking<false>
to control whether there's a bit on ilist_node "prev" pointer
indicating whether it's the sentinel. The default behaviour is to
use a bit if and only if LLVM_ENABLE_ABI_BREAKING_CHECKS.
2. Pass ilist_tag<TagA> and ilist_tag<TagB> to allow insertion of a
single node into two different lists (simultaneously).
I have an immediate use-case for (1) ilist_sentinel_tracking: fixing the
validation semantics of MachineBasicBlock::reverse_iterator to match
ilist::reverse_iterator (ala r280032: see the comments at the end of the
commit message there). I'm adding (2) ilist_tag in the same commit to
validate that the options framework supports expansion. Justin Bogner
mentioned this might enable a possible cleanup in SelectionDAG, but I'll
leave this to others to explore. In the meantime, the unit tests and
the comments for simple_ilist and ilist_node have usage examples.
Note that there's a layer of indirection to support optional,
out-of-order, template paramaters. Internal classes are templated on an
instantiation of the non-variadic ilist_detail::node_options.
User-facing classes use ilist_detail::compute_node_options to compute
the correct instantiation of ilist_detail::node_options.
The comments for ilist_detail::is_valid_option describe how to add new
options (e.g., ilist_packed_int<int NumBits>).
llvm-svn: 281167
54 lines
1.7 KiB
C++
54 lines
1.7 KiB
C++
//===- llvm/ADT/ilist_node_base.h - Intrusive List Node Base -----*- C++ -*-==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_ILIST_NODE_BASE_H
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#define LLVM_ADT_ILIST_NODE_BASE_H
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#include "llvm/ADT/PointerIntPair.h"
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namespace llvm {
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/// Base class for ilist nodes.
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///
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/// Optionally tracks whether this node is the sentinel.
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template <bool EnableSentinelTracking> class ilist_node_base;
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template <> class ilist_node_base<false> {
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ilist_node_base *Prev = nullptr;
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ilist_node_base *Next = nullptr;
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public:
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void setPrev(ilist_node_base *Prev) { this->Prev = Prev; }
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void setNext(ilist_node_base *Next) { this->Next = Next; }
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ilist_node_base *getPrev() const { return Prev; }
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ilist_node_base *getNext() const { return Next; }
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bool isKnownSentinel() const { return false; }
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void initializeSentinel() {}
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};
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template <> class ilist_node_base<true> {
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PointerIntPair<ilist_node_base *, 1> PrevAndSentinel;
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ilist_node_base *Next = nullptr;
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public:
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void setPrev(ilist_node_base *Prev) { PrevAndSentinel.setPointer(Prev); }
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void setNext(ilist_node_base *Next) { this->Next = Next; }
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ilist_node_base *getPrev() const { return PrevAndSentinel.getPointer(); }
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ilist_node_base *getNext() const { return Next; }
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bool isSentinel() const { return PrevAndSentinel.getInt(); }
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bool isKnownSentinel() const { return isSentinel(); }
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void initializeSentinel() { PrevAndSentinel.setInt(true); }
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};
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} // end namespace llvm
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#endif // LLVM_ADT_ILIST_NODE_BASE_H
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