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