[llvm] r339689 - Expose CFG Update struct. Define GraphTraits to get children given a snapshot CFG.
Raphael Isemann via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 14 14:18:10 PDT 2018
Jep, it works! Thanks for fixing this!
Am Di., 14. Aug. 2018 um 14:01 Uhr schrieb Alina Sbirlea <asbirlea at google.com>:
>
> Hope rL339724 (D50734) fixed this.
> Thank you for the heads up!
>
> On Tue, Aug 14, 2018 at 11:25 AM Raphael Isemann <teemperor at gmail.com> wrote:
>>
>> >+#include "llvm/IR/BasicBlock.h"
>> >+#include "llvm/IR/CFG.h"
>>
>> These includes just broke the LLVM_ENABLE_MODULES build (at least it
>> will once the modules bot will be finished building, but it already
>> fails locally for me).
>>
>> Anyone knows if this actually breaks the layering or if we just need
>> to restructure the modulemap? Don't know that code well enough.
>>
>> > While building module 'LLVM_DebugInfo_PDB' imported from /Users/teemperor/llvm/thirdstuff/llvm/lib/DebugInfo/PDB/IPDBSourceFile.cpp:10:
>> > While building module 'LLVM_DebugInfo' imported from /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/DebugInfo/PDB/PDBContext.h:13:
>> > While building module 'LLVM_Object' imported from /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/DebugInfo/DIContext.h:19:
>> > While building module 'LLVM_IR' imported from /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/Object/IRSymtab.h:30:
>> > While building module 'LLVM_intrinsic_gen' imported from /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/IR/CFGDiff.h:22:
>> > In file included from <module-includes>:1:
>> > /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/IR/Argument.h:20:10: fatal error: cyclic dependency in module 'LLVM_IR': LLVM_IR -> LLVM_intrinsic_gen -> LLVM_IR
>> > #include "llvm/IR/Value.h"
>> > ^
>> > While building module 'LLVM_DebugInfo_PDB' imported from /Users/teemperor/llvm/thirdstuff/llvm/lib/DebugInfo/PDB/IPDBSourceFile.cpp:10:
>> > While building module 'LLVM_DebugInfo' imported from /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/DebugInfo/PDB/PDBContext.h:13:
>> > While building module 'LLVM_Object' imported from /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/DebugInfo/DIContext.h:19:
>> > While building module 'LLVM_IR' imported from /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/Object/IRSymtab.h:30:
>> > In file included from <module-includes>:32:
>> > /Users/teemperor/llvm/thirdstuff/llvm/include/llvm/IR/CFGDiff.h:22:10: fatal error: could not build module 'LLVM_intrinsic_gen'
>> > #include "llvm/IR/CFG.h"
>> > ~~~~~~~~^~~~~~~~~~~~~~~
>>
>> Am Di., 14. Aug. 2018 um 09:45 Uhr schrieb Alina Sbirlea via
>> llvm-commits <llvm-commits at lists.llvm.org>:
>> >
>> > Author: asbirlea
>> > Date: Tue Aug 14 09:44:28 2018
>> > New Revision: 339689
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=339689&view=rev
>> > Log:
>> > Expose CFG Update struct. Define GraphTraits to get children given a snapshot CFG.
>> >
>> > Summary:
>> > Certain passes or analysis need to view a CFG snapshot rather than the actual CFG. This patch provides GraphTraits to offer such a view.
>> >
>> > The patch defines GraphTraits for BasicBlock* and Inverse<BasicBlock*> to provide CFG successors and predecessors based on a list of CFG updates.
>> >
>> > An Update is defined as a triple {InsertOrDeleteKind, BlockStartOfEdge, BlockEndOfEdge}.
>> > A GraphDiff is defined as a list of Updates that has been preprocessed to treat the CFG as a graph rather than a multi-graph. As such, there can only exist a single Update given two nodes. All duplicates will be filtered and Insert/Delete edges that cancel out will be ignored.
>> > The methods GraphDiff exposes are:
>> > - Determine if an existing child needs to be ignored, i.e. an Update exists in the correct direction to assume the removal of that edge.
>> > - Return a list of new children to be considered, i.e. an Update exists in the correct direction for each child in the list to assume the insertion of that edge.
>> >
>> > Reviewers: timshen, kuhar, chandlerc
>> >
>> > Subscribers: sanjoy, jlebar, llvm-commits
>> >
>> > Differential Revision: https://reviews.llvm.org/D50479
>> >
>> > Added:
>> > llvm/trunk/include/llvm/IR/CFGDiff.h
>> > llvm/trunk/include/llvm/Support/CFGUpdate.h
>> > Modified:
>> > llvm/trunk/include/llvm/ADT/iterator.h
>> >
>> > Modified: llvm/trunk/include/llvm/ADT/iterator.h
>> > URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/iterator.h?rev=339689&r1=339688&r2=339689&view=diff
>> > ==============================================================================
>> > --- llvm/trunk/include/llvm/ADT/iterator.h (original)
>> > +++ llvm/trunk/include/llvm/ADT/iterator.h Tue Aug 14 09:44:28 2018
>> > @@ -334,6 +334,34 @@ make_pointer_range(RangeT &&Range) {
>> > PointerIteratorT(std::end(std::forward<RangeT>(Range))));
>> > }
>> >
>> > +// Wrapper iterator over iterator ItType, adding DataRef to the type of ItType,
>> > +// to create NodeRef = std::pair<InnerTypeOfItType, DataRef>.
>> > +template <typename ItType, typename NodeRef, typename DataRef>
>> > +class WrappedPairNodeDataIterator
>> > + : public iterator_adaptor_base<
>> > + WrappedPairNodeDataIterator<ItType, NodeRef, DataRef>, ItType,
>> > + typename std::iterator_traits<ItType>::iterator_category, NodeRef,
>> > + std::ptrdiff_t, NodeRef *, NodeRef &> {
>> > + using BaseT = iterator_adaptor_base<
>> > + WrappedPairNodeDataIterator, ItType,
>> > + typename std::iterator_traits<ItType>::iterator_category, NodeRef,
>> > + std::ptrdiff_t, NodeRef *, NodeRef &>;
>> > +
>> > + const DataRef DR;
>> > + mutable NodeRef NR;
>> > +
>> > +public:
>> > + WrappedPairNodeDataIterator(ItType Begin, const DataRef DR)
>> > + : BaseT(Begin), DR(DR) {
>> > + NR.first = DR;
>> > + }
>> > +
>> > + NodeRef &operator*() const {
>> > + NR.second = *this->I;
>> > + return NR;
>> > + }
>> > +};
>> > +
>> > } // end namespace llvm
>> >
>> > #endif // LLVM_ADT_ITERATOR_H
>> >
>> > Added: llvm/trunk/include/llvm/IR/CFGDiff.h
>> > URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/CFGDiff.h?rev=339689&view=auto
>> > ==============================================================================
>> > --- llvm/trunk/include/llvm/IR/CFGDiff.h (added)
>> > +++ llvm/trunk/include/llvm/IR/CFGDiff.h Tue Aug 14 09:44:28 2018
>> > @@ -0,0 +1,286 @@
>> > +//===- CFGDiff.h - Define a CFG snapshot. -----------------------*- C++ -*-===//
>> > +//
>> > +// The LLVM Compiler Infrastructure
>> > +//
>> > +// This file is distributed under the University of Illinois Open Source
>> > +// License. See LICENSE.TXT for details.
>> > +//
>> > +//===----------------------------------------------------------------------===//
>> > +//
>> > +// This file defines specializations of GraphTraits that allows generic
>> > +// algorithms to see a different snapshot of a CFG.
>> > +//
>> > +//===----------------------------------------------------------------------===//
>> > +
>> > +#ifndef LLVM_IR_CFGDIFF_H
>> > +#define LLVM_IR_CFGDIFF_H
>> > +
>> > +#include "llvm/ADT/GraphTraits.h"
>> > +#include "llvm/ADT/iterator.h"
>> > +#include "llvm/ADT/iterator_range.h"
>> > +#include "llvm/IR/BasicBlock.h"
>> > +#include "llvm/IR/CFG.h"
>> > +#include "llvm/Support/CFGUpdate.h"
>> > +#include "llvm/Support/type_traits.h"
>> > +#include <cassert>
>> > +#include <cstddef>
>> > +#include <iterator>
>> > +
>> > +// Two booleans are used to define orders in graphs:
>> > +// InverseGraph defines when we need to reverse the whole graph and is as such
>> > +// also equivalent to applying updates in reverse.
>> > +// InverseEdge defines whether we want to change the edges direction. E.g., for
>> > +// a non-inversed graph, the children are naturally the successors when
>> > +// InverseEdge is false and the predecessors when InverseEdge is true.
>> > +
>> > +// We define two base clases that call into GraphDiff, one for successors
>> > +// (CFGSuccessors), where InverseEdge is false, and one for predecessors
>> > +// (CFGPredecessors), where InverseEdge is true.
>> > +// FIXME: Further refactoring may merge the two base classes into a single one
>> > +// templated / parametrized on using succ_iterator/pred_iterator and false/true
>> > +// for the InverseEdge.
>> > +
>> > +// CFGViewSuccessors and CFGViewPredecessors, both can be parametrized to
>> > +// consider the graph inverted or not (i.e. InverseGraph). Successors
>> > +// implicitly has InverseEdge = false and Predecessors implicitly has
>> > +// InverseEdge = true (see calls to GraphDiff methods in there). The GraphTraits
>> > +// instantiations that follow define the value of InverseGraph.
>> > +
>> > +// GraphTraits instantiations:
>> > +// - GraphDiff<BasicBlock *> is equivalent to InverseGraph = false
>> > +// - GraphDiff<Inverse<BasicBlock *>> is equivalent to InverseGraph = true
>> > +// - second pair item is BasicBlock *, then InverseEdge = false (so it inherits
>> > +// from CFGViewSuccessors).
>> > +// - second pair item is Inverse<BasicBlock *>, then InverseEdge = true (so it
>> > +// inherits from CFGViewPredecessors).
>> > +
>> > +// The 4 GraphTraits are as follows:
>> > +// 1. std::pair<const GraphDiff<BasicBlock *> *, BasicBlock *>> :
>> > +// CFGViewSuccessors<false>
>> > +// Regular CFG, children means successors, InverseGraph = false,
>> > +// InverseEdge = false.
>> > +// 2. std::pair<const GraphDiff<Inverse<BasicBlock *>> *, BasicBlock *>> :
>> > +// CFGViewSuccessors<true>
>> > +// Reverse the graph, get successors but reverse-apply updates,
>> > +// InverseGraph = true, InverseEdge = false.
>> > +// 3. std::pair<const GraphDiff<BasicBlock *> *, Inverse<BasicBlock *>>> :
>> > +// CFGViewPredecessors<false>
>> > +// Regular CFG, reverse edges, so children mean predecessors,
>> > +// InverseGraph = false, InverseEdge = true.
>> > +// 4. std::pair<const GraphDiff<Inverse<BasicBlock *>> *, Inverse<BasicBlock *>>
>> > +// : CFGViewPredecessors<true>
>> > +// Reverse the graph and the edges, InverseGraph = true, InverseEdge = true.
>> > +
>> > +namespace llvm {
>> > +
>> > +// GraphDiff defines a CFG snapshot: given a set of Update<NodePtr>, provide
>> > +// utilities to skip edges marked as deleted and return a set of edges marked as
>> > +// newly inserted. The current diff treats the CFG as a graph rather than a
>> > +// multigraph. Added edges are pruned to be unique, and deleted edges will
>> > +// remove all existing edges between two blocks.
>> > +template <typename NodePtr> class GraphDiff {
>> > + using UpdateMapType = SmallDenseMap<NodePtr, SmallVector<NodePtr, 2>>;
>> > + UpdateMapType SuccInsert;
>> > + UpdateMapType SuccDelete;
>> > + UpdateMapType PredInsert;
>> > + UpdateMapType PredDelete;
>> > + // Using a singleton empty vector for all BasicBlock requests with no
>> > + // children.
>> > + SmallVector<NodePtr, 1> Empty;
>> > +
>> > + void printMap(raw_ostream &OS, const UpdateMapType &M) const {
>> > + for (auto Pair : M)
>> > + for (auto Child : Pair.second) {
>> > + OS << "(";
>> > + Pair.first->printAsOperand(OS, false);
>> > + OS << ", ";
>> > + Child->printAsOperand(OS, false);
>> > + OS << ") ";
>> > + }
>> > + OS << "\n";
>> > + }
>> > +
>> > +public:
>> > + GraphDiff() {}
>> > + GraphDiff(ArrayRef<cfg::Update<NodePtr>> Updates, bool InverseGraph = false) {
>> > + SmallVector<cfg::Update<NodePtr>, 4> LegalizedUpdates;
>> > + cfg::LegalizeUpdates<NodePtr>(Updates, LegalizedUpdates, InverseGraph);
>> > + for (auto U : LegalizedUpdates) {
>> > + if (U.getKind() == cfg::UpdateKind::Insert) {
>> > + SuccInsert[U.getFrom()].push_back(U.getTo());
>> > + PredInsert[U.getTo()].push_back(U.getFrom());
>> > + } else {
>> > + SuccDelete[U.getFrom()].push_back(U.getTo());
>> > + PredDelete[U.getTo()].push_back(U.getFrom());
>> > + }
>> > + }
>> > + }
>> > +
>> > + bool ignoreChild(const NodePtr BB, NodePtr EdgeEnd, bool InverseEdge,
>> > + bool InverseGraph) const {
>> > + auto &DeleteChildren =
>> > + (InverseEdge != InverseGraph) ? PredDelete : SuccDelete;
>> > + auto It = DeleteChildren.find(BB);
>> > + if (It == DeleteChildren.end())
>> > + return false;
>> > + auto &EdgesForBB = It->second;
>> > + return llvm::find(EdgesForBB, EdgeEnd) != EdgesForBB.end();
>> > + }
>> > +
>> > + iterator_range<typename SmallVectorImpl<NodePtr>::const_iterator>
>> > + getAddedChildren(const NodePtr BB, bool InverseEdge,
>> > + bool InverseGraph) const {
>> > + auto &InsertChildren =
>> > + (InverseEdge != InverseGraph) ? PredInsert : SuccInsert;
>> > + auto It = InsertChildren.find(BB);
>> > + if (It == InsertChildren.end())
>> > + return make_range(Empty.begin(), Empty.end());
>> > + return make_range(It->second.begin(), It->second.end());
>> > + }
>> > +
>> > + void print(raw_ostream &OS) const {
>> > + OS << "===== GraphDiff: CFG edge changes to create a CFG snapshot. \n"
>> > + "===== (Note: notion of children/inverse_children depends on "
>> > + "the direction of edges and the graph.)\n";
>> > + OS << "Children to insert:\n\t";
>> > + printMap(OS, SuccInsert);
>> > + OS << "Children to delete:\n\t";
>> > + printMap(OS, SuccDelete);
>> > + OS << "Inverse_children to insert:\n\t";
>> > + printMap(OS, PredInsert);
>> > + OS << "Inverse_children to delete:\n\t";
>> > + printMap(OS, PredDelete);
>> > + OS << "\n";
>> > + }
>> > +
>> > +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
>> > + LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
>> > +#endif
>> > +};
>> > +
>> > +template <bool InverseGraph = false> struct CFGViewSuccessors {
>> > + using DataRef = const GraphDiff<BasicBlock *> *;
>> > + using NodeRef = std::pair<DataRef, BasicBlock *>;
>> > +
>> > + using ExistingChildIterator =
>> > + WrappedPairNodeDataIterator<succ_iterator, NodeRef, DataRef>;
>> > + struct DeletedEdgesFilter {
>> > + BasicBlock *BB;
>> > + DeletedEdgesFilter(BasicBlock *BB) : BB(BB){};
>> > + bool operator()(NodeRef N) const {
>> > + return !N.first->ignoreChild(BB, N.second, false, InverseGraph);
>> > + }
>> > + };
>> > + using FilterExistingChildrenIterator =
>> > + filter_iterator<ExistingChildIterator, DeletedEdgesFilter>;
>> > +
>> > + using vec_iterator = SmallVectorImpl<BasicBlock *>::const_iterator;
>> > + using AddNewChildrenIterator =
>> > + WrappedPairNodeDataIterator<vec_iterator, NodeRef, DataRef>;
>> > + using ChildIteratorType =
>> > + concat_iterator<NodeRef, FilterExistingChildrenIterator,
>> > + AddNewChildrenIterator>;
>> > +
>> > + static ChildIteratorType child_begin(NodeRef N) {
>> > + auto InsertVec = N.first->getAddedChildren(N.second, false, InverseGraph);
>> > + // filter iterator init:
>> > + auto firstit = make_filter_range(
>> > + make_range<ExistingChildIterator>({succ_begin(N.second), N.first},
>> > + {succ_end(N.second), N.first}),
>> > + DeletedEdgesFilter(N.second));
>> > + // new inserts iterator init:
>> > + auto secondit = make_range<AddNewChildrenIterator>(
>> > + {InsertVec.begin(), N.first}, {InsertVec.end(), N.first});
>> > +
>> > + return concat_iterator<NodeRef, FilterExistingChildrenIterator,
>> > + AddNewChildrenIterator>(firstit, secondit);
>> > + }
>> > +
>> > + static ChildIteratorType child_end(NodeRef N) {
>> > + auto InsertVec = N.first->getAddedChildren(N.second, false, InverseGraph);
>> > + // filter iterator init:
>> > + auto firstit = make_filter_range(
>> > + make_range<ExistingChildIterator>({succ_end(N.second), N.first},
>> > + {succ_end(N.second), N.first}),
>> > + DeletedEdgesFilter(N.second));
>> > + // new inserts iterator init:
>> > + auto secondit = make_range<AddNewChildrenIterator>(
>> > + {InsertVec.end(), N.first}, {InsertVec.end(), N.first});
>> > +
>> > + return concat_iterator<NodeRef, FilterExistingChildrenIterator,
>> > + AddNewChildrenIterator>(firstit, secondit);
>> > + }
>> > +};
>> > +
>> > +template <bool InverseGraph = false> struct CFGViewPredecessors {
>> > + using DataRef = const GraphDiff<BasicBlock *> *;
>> > + using NodeRef = std::pair<DataRef, BasicBlock *>;
>> > +
>> > + using ExistingChildIterator =
>> > + WrappedPairNodeDataIterator<pred_iterator, NodeRef, DataRef>;
>> > + struct DeletedEdgesFilter {
>> > + BasicBlock *BB;
>> > + DeletedEdgesFilter(BasicBlock *BB) : BB(BB){};
>> > + bool operator()(NodeRef N) const {
>> > + return !N.first->ignoreChild(BB, N.second, true, InverseGraph);
>> > + }
>> > + };
>> > + using FilterExistingChildrenIterator =
>> > + filter_iterator<ExistingChildIterator, DeletedEdgesFilter>;
>> > +
>> > + using vec_iterator = SmallVectorImpl<BasicBlock *>::const_iterator;
>> > + using AddNewChildrenIterator =
>> > + WrappedPairNodeDataIterator<vec_iterator, NodeRef, DataRef>;
>> > + using ChildIteratorType =
>> > + concat_iterator<NodeRef, FilterExistingChildrenIterator,
>> > + AddNewChildrenIterator>;
>> > +
>> > + static ChildIteratorType child_begin(NodeRef N) {
>> > + auto InsertVec = N.first->getAddedChildren(N.second, true, InverseGraph);
>> > + // filter iterator init:
>> > + auto firstit = make_filter_range(
>> > + make_range<ExistingChildIterator>({pred_begin(N.second), N.first},
>> > + {pred_end(N.second), N.first}),
>> > + DeletedEdgesFilter(N.second));
>> > + // new inserts iterator init:
>> > + auto secondit = make_range<AddNewChildrenIterator>(
>> > + {InsertVec.begin(), N.first}, {InsertVec.end(), N.first});
>> > +
>> > + return concat_iterator<NodeRef, FilterExistingChildrenIterator,
>> > + AddNewChildrenIterator>(firstit, secondit);
>> > + }
>> > +
>> > + static ChildIteratorType child_end(NodeRef N) {
>> > + auto InsertVec = N.first->getAddedChildren(N.second, true, InverseGraph);
>> > + // filter iterator init:
>> > + auto firstit = make_filter_range(
>> > + make_range<ExistingChildIterator>({pred_end(N.second), N.first},
>> > + {pred_end(N.second), N.first}),
>> > + DeletedEdgesFilter(N.second));
>> > + // new inserts iterator init:
>> > + auto secondit = make_range<AddNewChildrenIterator>(
>> > + {InsertVec.end(), N.first}, {InsertVec.end(), N.first});
>> > +
>> > + return concat_iterator<NodeRef, FilterExistingChildrenIterator,
>> > + AddNewChildrenIterator>(firstit, secondit);
>> > + }
>> > +};
>> > +
>> > +template <>
>> > +struct GraphTraits<std::pair<const GraphDiff<BasicBlock *> *, BasicBlock *>>
>> > + : CFGViewSuccessors<false> {};
>> > +template <>
>> > +struct GraphTraits<
>> > + std::pair<const GraphDiff<Inverse<BasicBlock *>> *, BasicBlock *>>
>> > + : CFGViewSuccessors<true> {};
>> > +template <>
>> > +struct GraphTraits<
>> > + std::pair<const GraphDiff<BasicBlock *> *, Inverse<BasicBlock *>>>
>> > + : CFGViewPredecessors<false> {};
>> > +template <>
>> > +struct GraphTraits<
>> > + std::pair<const GraphDiff<Inverse<BasicBlock *>> *, Inverse<BasicBlock *>>>
>> > + : CFGViewPredecessors<true> {};
>> > +} // end namespace llvm
>> > +
>> > +#endif // LLVM_IR_CFGDIFF_H
>> >
>> > Added: llvm/trunk/include/llvm/Support/CFGUpdate.h
>> > URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/CFGUpdate.h?rev=339689&view=auto
>> > ==============================================================================
>> > --- llvm/trunk/include/llvm/Support/CFGUpdate.h (added)
>> > +++ llvm/trunk/include/llvm/Support/CFGUpdate.h Tue Aug 14 09:44:28 2018
>> > @@ -0,0 +1,113 @@
>> > +//===- CFGUpdate.h - Encode a CFG Edge Update. ------------------*- C++ -*-===//
>> > +//
>> > +// The LLVM Compiler Infrastructure
>> > +//
>> > +// This file is distributed under the University of Illinois Open Source
>> > +// License. See LICENSE.TXT for details.
>> > +//
>> > +//===----------------------------------------------------------------------===//
>> > +//
>> > +// This file defines a CFG Edge Update: Insert or Delete, and two Nodes as the
>> > +// Edge ends.
>> > +//
>> > +//===----------------------------------------------------------------------===//
>> > +
>> > +#ifndef LLVM_SUPPORT_CFGUPDATE_H
>> > +#define LLVM_SUPPORT_CFGUPDATE_H
>> > +
>> > +#include "llvm/Support/Debug.h"
>> > +
>> > +namespace llvm {
>> > +namespace cfg {
>> > +enum class UpdateKind : unsigned char { Insert, Delete };
>> > +
>> > +template <typename NodePtr> class Update {
>> > + using NodeKindPair = PointerIntPair<NodePtr, 1, UpdateKind>;
>> > + NodePtr From;
>> > + NodeKindPair ToAndKind;
>> > +
>> > +public:
>> > + Update(UpdateKind Kind, NodePtr From, NodePtr To)
>> > + : From(From), ToAndKind(To, Kind) {}
>> > +
>> > + UpdateKind getKind() const { return ToAndKind.getInt(); }
>> > + NodePtr getFrom() const { return From; }
>> > + NodePtr getTo() const { return ToAndKind.getPointer(); }
>> > + bool operator==(const Update &RHS) const {
>> > + return From == RHS.From && ToAndKind == RHS.ToAndKind;
>> > + }
>> > +
>> > + void print(raw_ostream &OS) const {
>> > + OS << (getKind() == UpdateKind::Insert ? "Insert " : "Delete ");
>> > + getFrom()->printAsOperand(OS, false);
>> > + OS << " -> ";
>> > + getTo()->printAsOperand(OS, false);
>> > + }
>> > +
>> > +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
>> > + LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
>> > +#endif
>> > +};
>> > +
>> > +// LegalizeUpdates function simplifies updates assuming a graph structure.
>> > +// This function serves double purpose:
>> > +// a) It removes redundant updates, which makes it easier to reverse-apply
>> > +// them when traversing CFG.
>> > +// b) It optimizes away updates that cancel each other out, as the end result
>> > +// is the same.
>> > +template <typename NodePtr>
>> > +void LegalizeUpdates(ArrayRef<Update<NodePtr>> AllUpdates,
>> > + SmallVectorImpl<Update<NodePtr>> &Result,
>> > + bool InverseGraph) {
>> > + // Count the total number of inserions of each edge.
>> > + // Each insertion adds 1 and deletion subtracts 1. The end number should be
>> > + // one of {-1 (deletion), 0 (NOP), +1 (insertion)}. Otherwise, the sequence
>> > + // of updates contains multiple updates of the same kind and we assert for
>> > + // that case.
>> > + SmallDenseMap<std::pair<NodePtr, NodePtr>, int, 4> Operations;
>> > + Operations.reserve(AllUpdates.size());
>> > +
>> > + for (const auto &U : AllUpdates) {
>> > + NodePtr From = U.getFrom();
>> > + NodePtr To = U.getTo();
>> > + if (InverseGraph)
>> > + std::swap(From, To); // Reverse edge for postdominators.
>> > +
>> > + Operations[{From, To}] += (U.getKind() == UpdateKind::Insert ? 1 : -1);
>> > + }
>> > +
>> > + Result.clear();
>> > + Result.reserve(Operations.size());
>> > + for (auto &Op : Operations) {
>> > + const int NumInsertions = Op.second;
>> > + assert(std::abs(NumInsertions) <= 1 && "Unbalanced operations!");
>> > + if (NumInsertions == 0)
>> > + continue;
>> > + const UpdateKind UK =
>> > + NumInsertions > 0 ? UpdateKind::Insert : UpdateKind::Delete;
>> > + Result.push_back({UK, Op.first.first, Op.first.second});
>> > + }
>> > +
>> > + // Make the order consistent by not relying on pointer values within the
>> > + // set. Reuse the old Operations map.
>> > + // In the future, we should sort by something else to minimize the amount
>> > + // of work needed to perform the series of updates.
>> > + for (size_t i = 0, e = AllUpdates.size(); i != e; ++i) {
>> > + const auto &U = AllUpdates[i];
>> > + if (!InverseGraph)
>> > + Operations[{U.getFrom(), U.getTo()}] = int(i);
>> > + else
>> > + Operations[{U.getTo(), U.getFrom()}] = int(i);
>> > + }
>> > +
>> > + llvm::sort(Result.begin(), Result.end(),
>> > + [&Operations](const Update<NodePtr> &A, const Update<NodePtr> &B) {
>> > + return Operations[{A.getFrom(), A.getTo()}] >
>> > + Operations[{B.getFrom(), B.getTo()}];
>> > + });
>> > +}
>> > +
>> > +} // end namespace cfg
>> > +} // end namespace llvm
>> > +
>> > +#endif // LLVM_SUPPORT_CFGUPDATE_H
>> >
>> >
>> > _______________________________________________
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>> > llvm-commits at lists.llvm.org
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