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llvm-mirror/tools/llvm-xray/trie-node.h
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

92 lines
3.3 KiB
C++

//===- trie-node.h - XRay Call Stack Data Structure -----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file provides a data structure and routines for working with call stacks
// of instrumented functions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_XRAY_STACK_TRIE_H
#define LLVM_TOOLS_LLVM_XRAY_STACK_TRIE_H
#include <forward_list>
#include <numeric>
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
/// A type to represent a trie of invocations. It is useful to construct a
/// graph of these nodes from reading an XRay trace, such that each function
/// call can be placed in a larger context.
///
/// The template parameter allows users of the template to attach their own
/// data elements to each node in the invocation graph.
template <typename AssociatedData> struct TrieNode {
/// The function ID.
int32_t FuncId;
/// The caller of this function.
TrieNode<AssociatedData> *Parent;
/// The callees from this function.
llvm::SmallVector<TrieNode<AssociatedData> *, 4> Callees;
/// Additional parameterized data on each node.
AssociatedData ExtraData;
};
/// Merges together two TrieNodes with like function ids, aggregating their
/// callee lists and durations. The caller must provide storage where new merged
/// nodes can be allocated in the form of a linked list.
template <typename T, typename Callable>
TrieNode<T> *
mergeTrieNodes(const TrieNode<T> &Left, const TrieNode<T> &Right,
/*Non-deduced pointer type for nullptr compatibility*/
typename std::remove_reference<TrieNode<T> *>::type NewParent,
std::forward_list<TrieNode<T>> &NodeStore,
Callable &&MergeCallable) {
llvm::function_ref<T(const T &, const T &)> MergeFn(
std::forward<Callable>(MergeCallable));
assert(Left.FuncId == Right.FuncId);
NodeStore.push_front(TrieNode<T>{
Left.FuncId, NewParent, {}, MergeFn(Left.ExtraData, Right.ExtraData)});
auto I = NodeStore.begin();
auto *Node = &*I;
// Build a map of callees from the left side.
llvm::DenseMap<int32_t, TrieNode<T> *> LeftCalleesByFuncId;
for (auto *Callee : Left.Callees) {
LeftCalleesByFuncId[Callee->FuncId] = Callee;
}
// Iterate through the right side, either merging with the map values or
// directly adding to the Callees vector. The iteration also removes any
// merged values from the left side map.
// TODO: Unroll into iterative and explicit stack for efficiency.
for (auto *Callee : Right.Callees) {
auto iter = LeftCalleesByFuncId.find(Callee->FuncId);
if (iter != LeftCalleesByFuncId.end()) {
Node->Callees.push_back(
mergeTrieNodes(*(iter->second), *Callee, Node, NodeStore, MergeFn));
LeftCalleesByFuncId.erase(iter);
} else {
Node->Callees.push_back(Callee);
}
}
// Add any callees that weren't found in the right side.
for (auto MapPairIter : LeftCalleesByFuncId) {
Node->Callees.push_back(MapPairIter.second);
}
return Node;
}
#endif // LLVM_TOOLS_LLVM_XRAY_STACK_TRIE_H