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9200890ea3
Split out a new, low-level intrusive list type with clear semantics.
Unlike iplist (and ilist), all operations on simple_ilist are intrusive,
and simple_ilist never takes ownership of its nodes. This enables an
intuitive API that has the right defaults for intrusive lists.
- insert() takes references (not pointers!) to nodes (in iplist/ilist,
passing a reference will cause the node to be copied).
- erase() takes only iterators (like std::list), and does not destroy
the nodes.
- remove() takes only references and has the same behaviour as erase().
- clear() does not destroy the nodes.
- The destructor does not destroy the nodes.
- New API {erase,remove,clear}AndDispose() take an extra Disposer
functor for callsites that want to call some disposal routine (e.g.,
std::default_delete).
This list is not currently configurable, and has no callbacks.
The initial motivation was to fix iplist<>::sort to work correctly (even
with callbacks in ilist_traits<>). iplist<> uses simple_ilist<>::sort
directly. The new test in unittests/IR/ModuleTest.cpp crashes without
this commit.
Fixing sort() via a low-level layer provided a good opportunity to:
- Unit test the low-level functionality thoroughly.
- Modernize the API, largely inspired by other intrusive list
implementations.
Here's a sketch of a longer-term plan:
- Create BumpPtrList<>, a non-intrusive list implemented using
simple_ilist<>, and use it for the Token list in
lib/Support/YAMLParser.cpp. This will factor out the only real use of
createNode().
- Evolve the iplist<> and ilist<> APIs in the direction of
simple_ilist<>, making allocation/deallocation explicit at call sites
(similar to simple_ilist<>::eraseAndDispose()).
- Factor out remaining calls to createNode() and deleteNode() and remove
the customization from ilist_traits<>.
- Transition uses of iplist<>/ilist<> that don't need callbacks over to
simple_ilist<>.
llvm-svn: 280107
94 lines
2.6 KiB
C++
94 lines
2.6 KiB
C++
//===- llvm/ADT/ilist_base.h - Intrusive List 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_BASE_H
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#define LLVM_ADT_ILIST_BASE_H
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#include "llvm/ADT/ilist_node_base.h"
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#include <cassert>
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#include <cstddef>
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#include <type_traits>
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namespace llvm {
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/// Implementations of list algorithms using ilist_node_base.
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class ilist_base {
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public:
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static void insertBeforeImpl(ilist_node_base &Next, ilist_node_base &N) {
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ilist_node_base &Prev = *Next.getPrev();
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N.setNext(&Next);
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N.setPrev(&Prev);
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Prev.setNext(&N);
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Next.setPrev(&N);
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}
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static void removeImpl(ilist_node_base &N) {
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ilist_node_base *Prev = N.getPrev();
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ilist_node_base *Next = N.getNext();
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Next->setPrev(Prev);
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Prev->setNext(Next);
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// Not strictly necessary, but helps catch a class of bugs.
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N.setPrev(nullptr);
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N.setNext(nullptr);
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}
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static void removeRangeImpl(ilist_node_base &First, ilist_node_base &Last) {
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ilist_node_base *Prev = First.getPrev();
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ilist_node_base *Final = Last.getPrev();
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Last.setPrev(Prev);
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Prev->setNext(&Last);
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// Not strictly necessary, but helps catch a class of bugs.
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First.setPrev(nullptr);
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Final->setNext(nullptr);
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}
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static void transferBeforeImpl(ilist_node_base &Next, ilist_node_base &First,
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ilist_node_base &Last) {
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if (&Next == &Last || &First == &Last)
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return;
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// Position cannot be contained in the range to be transferred.
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assert(&Next != &First &&
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// Check for the most common mistake.
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"Insertion point can't be one of the transferred nodes");
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ilist_node_base &Final = *Last.getPrev();
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// Detach from old list/position.
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First.getPrev()->setNext(&Last);
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Last.setPrev(First.getPrev());
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// Splice [First, Final] into its new list/position.
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ilist_node_base &Prev = *Next.getPrev();
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Final.setNext(&Next);
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First.setPrev(&Prev);
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Prev.setNext(&First);
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Next.setPrev(&Final);
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}
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template <class T> static void insertBefore(T &Next, T &N) {
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insertBeforeImpl(Next, N);
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}
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template <class T> static void remove(T &N) { removeImpl(N); }
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template <class T> static void removeRange(T &First, T &Last) {
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removeRangeImpl(First, Last);
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}
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template <class T> static void transferBefore(T &Next, T &First, T &Last) {
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transferBeforeImpl(Next, First, Last);
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}
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};
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} // end namespace llvm
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#endif // LLVM_ADT_ILIST_BASE_H
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