266 lines
10 KiB
C
266 lines
10 KiB
C
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//===- IntervalIterator.h - Interval Iterator Declaration -------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines an iterator that enumerates the intervals in a control flow
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// graph of some sort. This iterator is parametric, allowing iterator over the
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// following types of graphs:
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//
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// 1. A Function* object, composed of BasicBlock nodes.
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// 2. An IntervalPartition& object, composed of Interval nodes.
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//
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// This iterator is defined to walk the control flow graph, returning intervals
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// in depth first order. These intervals are completely filled in except for
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// the predecessor fields (the successor information is filled in however).
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//
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// By default, the intervals created by this iterator are deleted after they
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// are no longer any use to the iterator. This behavior can be changed by
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// passing a false value into the intervals_begin() function. This causes the
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// IOwnMem member to be set, and the intervals to not be deleted.
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//
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// It is only safe to use this if all of the intervals are deleted by the caller
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// and all of the intervals are processed. However, the user of the iterator is
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// not allowed to modify or delete the intervals until after the iterator has
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// been used completely. The IntervalPartition class uses this functionality.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_INTERVALITERATOR_H
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#define LLVM_ANALYSIS_INTERVALITERATOR_H
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/Analysis/Interval.h"
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#include "llvm/Analysis/IntervalPartition.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Function.h"
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#include "llvm/Support/ErrorHandling.h"
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#include <algorithm>
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#include <cassert>
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#include <iterator>
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#include <set>
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#include <utility>
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#include <vector>
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namespace llvm {
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class BasicBlock;
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// getNodeHeader - Given a source graph node and the source graph, return the
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// BasicBlock that is the header node. This is the opposite of
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// getSourceGraphNode.
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inline BasicBlock *getNodeHeader(BasicBlock *BB) { return BB; }
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inline BasicBlock *getNodeHeader(Interval *I) { return I->getHeaderNode(); }
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// getSourceGraphNode - Given a BasicBlock and the source graph, return the
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// source graph node that corresponds to the BasicBlock. This is the opposite
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// of getNodeHeader.
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inline BasicBlock *getSourceGraphNode(Function *, BasicBlock *BB) {
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return BB;
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}
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inline Interval *getSourceGraphNode(IntervalPartition *IP, BasicBlock *BB) {
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return IP->getBlockInterval(BB);
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}
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// addNodeToInterval - This method exists to assist the generic ProcessNode
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// with the task of adding a node to the new interval, depending on the
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// type of the source node. In the case of a CFG source graph (BasicBlock
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// case), the BasicBlock itself is added to the interval.
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inline void addNodeToInterval(Interval *Int, BasicBlock *BB) {
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Int->Nodes.push_back(BB);
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}
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// addNodeToInterval - This method exists to assist the generic ProcessNode
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// with the task of adding a node to the new interval, depending on the
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// type of the source node. In the case of a CFG source graph (BasicBlock
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// case), the BasicBlock itself is added to the interval. In the case of
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// an IntervalPartition source graph (Interval case), all of the member
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// BasicBlocks are added to the interval.
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inline void addNodeToInterval(Interval *Int, Interval *I) {
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// Add all of the nodes in I as new nodes in Int.
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llvm::append_range(Int->Nodes, I->Nodes);
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}
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template<class NodeTy, class OrigContainer_t, class GT = GraphTraits<NodeTy *>,
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class IGT = GraphTraits<Inverse<NodeTy *>>>
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class IntervalIterator {
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std::vector<std::pair<Interval *, typename Interval::succ_iterator>> IntStack;
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std::set<BasicBlock *> Visited;
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OrigContainer_t *OrigContainer;
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bool IOwnMem; // If True, delete intervals when done with them
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// See file header for conditions of use
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public:
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using iterator_category = std::forward_iterator_tag;
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IntervalIterator() = default; // End iterator, empty stack
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IntervalIterator(Function *M, bool OwnMemory) : IOwnMem(OwnMemory) {
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OrigContainer = M;
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if (!ProcessInterval(&M->front())) {
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llvm_unreachable("ProcessInterval should never fail for first interval!");
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}
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}
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IntervalIterator(IntervalIterator &&x)
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: IntStack(std::move(x.IntStack)), Visited(std::move(x.Visited)),
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OrigContainer(x.OrigContainer), IOwnMem(x.IOwnMem) {
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x.IOwnMem = false;
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}
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IntervalIterator(IntervalPartition &IP, bool OwnMemory) : IOwnMem(OwnMemory) {
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OrigContainer = &IP;
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if (!ProcessInterval(IP.getRootInterval())) {
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llvm_unreachable("ProcessInterval should never fail for first interval!");
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}
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}
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~IntervalIterator() {
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if (IOwnMem)
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while (!IntStack.empty()) {
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delete operator*();
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IntStack.pop_back();
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}
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}
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bool operator==(const IntervalIterator &x) const {
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return IntStack == x.IntStack;
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}
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bool operator!=(const IntervalIterator &x) const { return !(*this == x); }
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const Interval *operator*() const { return IntStack.back().first; }
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Interval *operator*() { return IntStack.back().first; }
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const Interval *operator->() const { return operator*(); }
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Interval *operator->() { return operator*(); }
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IntervalIterator &operator++() { // Preincrement
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assert(!IntStack.empty() && "Attempting to use interval iterator at end!");
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do {
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// All of the intervals on the stack have been visited. Try visiting
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// their successors now.
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Interval::succ_iterator &SuccIt = IntStack.back().second,
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EndIt = succ_end(IntStack.back().first);
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while (SuccIt != EndIt) { // Loop over all interval succs
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bool Done = ProcessInterval(getSourceGraphNode(OrigContainer, *SuccIt));
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++SuccIt; // Increment iterator
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if (Done) return *this; // Found a new interval! Use it!
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}
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// Free interval memory... if necessary
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if (IOwnMem) delete IntStack.back().first;
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// We ran out of successors for this interval... pop off the stack
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IntStack.pop_back();
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} while (!IntStack.empty());
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return *this;
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}
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IntervalIterator operator++(int) { // Postincrement
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IntervalIterator tmp = *this;
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++*this;
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return tmp;
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}
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private:
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// ProcessInterval - This method is used during the construction of the
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// interval graph. It walks through the source graph, recursively creating
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// an interval per invocation until the entire graph is covered. This uses
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// the ProcessNode method to add all of the nodes to the interval.
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//
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// This method is templated because it may operate on two different source
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// graphs: a basic block graph, or a preexisting interval graph.
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bool ProcessInterval(NodeTy *Node) {
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BasicBlock *Header = getNodeHeader(Node);
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if (!Visited.insert(Header).second)
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return false;
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Interval *Int = new Interval(Header);
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// Check all of our successors to see if they are in the interval...
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for (typename GT::ChildIteratorType I = GT::child_begin(Node),
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E = GT::child_end(Node); I != E; ++I)
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ProcessNode(Int, getSourceGraphNode(OrigContainer, *I));
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IntStack.push_back(std::make_pair(Int, succ_begin(Int)));
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return true;
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}
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// ProcessNode - This method is called by ProcessInterval to add nodes to the
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// interval being constructed, and it is also called recursively as it walks
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// the source graph. A node is added to the current interval only if all of
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// its predecessors are already in the graph. This also takes care of keeping
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// the successor set of an interval up to date.
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//
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// This method is templated because it may operate on two different source
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// graphs: a basic block graph, or a preexisting interval graph.
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void ProcessNode(Interval *Int, NodeTy *Node) {
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assert(Int && "Null interval == bad!");
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assert(Node && "Null Node == bad!");
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BasicBlock *NodeHeader = getNodeHeader(Node);
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if (Visited.count(NodeHeader)) { // Node already been visited?
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if (Int->contains(NodeHeader)) { // Already in this interval...
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return;
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} else { // In other interval, add as successor
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if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
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Int->Successors.push_back(NodeHeader);
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}
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} else { // Otherwise, not in interval yet
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for (typename IGT::ChildIteratorType I = IGT::child_begin(Node),
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E = IGT::child_end(Node); I != E; ++I) {
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if (!Int->contains(*I)) { // If pred not in interval, we can't be
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if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
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Int->Successors.push_back(NodeHeader);
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return; // See you later
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}
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}
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// If we get here, then all of the predecessors of BB are in the interval
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// already. In this case, we must add BB to the interval!
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addNodeToInterval(Int, Node);
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Visited.insert(NodeHeader); // The node has now been visited!
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if (Int->isSuccessor(NodeHeader)) {
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// If we were in the successor list from before... remove from succ list
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llvm::erase_value(Int->Successors, NodeHeader);
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}
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// Now that we have discovered that Node is in the interval, perhaps some
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// of its successors are as well?
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for (typename GT::ChildIteratorType It = GT::child_begin(Node),
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End = GT::child_end(Node); It != End; ++It)
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ProcessNode(Int, getSourceGraphNode(OrigContainer, *It));
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}
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}
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};
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using function_interval_iterator = IntervalIterator<BasicBlock, Function>;
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using interval_part_interval_iterator =
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IntervalIterator<Interval, IntervalPartition>;
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inline function_interval_iterator intervals_begin(Function *F,
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bool DeleteInts = true) {
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return function_interval_iterator(F, DeleteInts);
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}
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inline function_interval_iterator intervals_end(Function *) {
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return function_interval_iterator();
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}
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inline interval_part_interval_iterator
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intervals_begin(IntervalPartition &IP, bool DeleteIntervals = true) {
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return interval_part_interval_iterator(IP, DeleteIntervals);
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}
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inline interval_part_interval_iterator intervals_end(IntervalPartition &IP) {
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return interval_part_interval_iterator();
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}
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} // end namespace llvm
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#endif // LLVM_ANALYSIS_INTERVALITERATOR_H
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