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llvm-mirror/include/llvm/ADT/ilist_base.h
Duncan P. N. Exon Smith 2a55cf5af8 ADT: Add sentinel tracking and custom tags to ilists
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
2016-09-11 16:20:53 +00:00

96 lines
2.7 KiB
C++

//===- llvm/ADT/ilist_base.h - Intrusive List Base ---------------*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_ILIST_BASE_H
#define LLVM_ADT_ILIST_BASE_H
#include "llvm/ADT/ilist_node_base.h"
#include <cassert>
#include <cstddef>
#include <type_traits>
namespace llvm {
/// Implementations of list algorithms using ilist_node_base.
template <bool EnableSentinelTracking> class ilist_base {
public:
typedef ilist_node_base<EnableSentinelTracking> node_base_type;
static void insertBeforeImpl(node_base_type &Next, node_base_type &N) {
node_base_type &Prev = *Next.getPrev();
N.setNext(&Next);
N.setPrev(&Prev);
Prev.setNext(&N);
Next.setPrev(&N);
}
static void removeImpl(node_base_type &N) {
node_base_type *Prev = N.getPrev();
node_base_type *Next = N.getNext();
Next->setPrev(Prev);
Prev->setNext(Next);
// Not strictly necessary, but helps catch a class of bugs.
N.setPrev(nullptr);
N.setNext(nullptr);
}
static void removeRangeImpl(node_base_type &First, node_base_type &Last) {
node_base_type *Prev = First.getPrev();
node_base_type *Final = Last.getPrev();
Last.setPrev(Prev);
Prev->setNext(&Last);
// Not strictly necessary, but helps catch a class of bugs.
First.setPrev(nullptr);
Final->setNext(nullptr);
}
static void transferBeforeImpl(node_base_type &Next, node_base_type &First,
node_base_type &Last) {
if (&Next == &Last || &First == &Last)
return;
// Position cannot be contained in the range to be transferred.
assert(&Next != &First &&
// Check for the most common mistake.
"Insertion point can't be one of the transferred nodes");
node_base_type &Final = *Last.getPrev();
// Detach from old list/position.
First.getPrev()->setNext(&Last);
Last.setPrev(First.getPrev());
// Splice [First, Final] into its new list/position.
node_base_type &Prev = *Next.getPrev();
Final.setNext(&Next);
First.setPrev(&Prev);
Prev.setNext(&First);
Next.setPrev(&Final);
}
template <class T> static void insertBefore(T &Next, T &N) {
insertBeforeImpl(Next, N);
}
template <class T> static void remove(T &N) { removeImpl(N); }
template <class T> static void removeRange(T &First, T &Last) {
removeRangeImpl(First, Last);
}
template <class T> static void transferBefore(T &Next, T &First, T &Last) {
transferBeforeImpl(Next, First, Last);
}
};
} // end namespace llvm
#endif // LLVM_ADT_ILIST_BASE_H