1 //===- llvm/Analysis/MemoryProfileInfo.h - memory profile info ---*- C++ -*-==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains utilities to analyze memory profile information.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef LLVM_ANALYSIS_MEMORYPROFILEINFO_H
14 #define LLVM_ANALYSIS_MEMORYPROFILEINFO_H
15
16 #include "llvm/IR/Constants.h"
17 #include "llvm/IR/InstrTypes.h"
18 #include "llvm/IR/Metadata.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/IR/ModuleSummaryIndex.h"
21 #include <map>
22
23 namespace llvm {
24 namespace memprof {
25
26 /// Return the allocation type for a given set of memory profile values.
27 AllocationType getAllocType(uint64_t MaxAccessCount, uint64_t MinSize,
28 uint64_t MinLifetime);
29
30 /// Build callstack metadata from the provided list of call stack ids. Returns
31 /// the resulting metadata node.
32 MDNode *buildCallstackMetadata(ArrayRef<uint64_t> CallStack, LLVMContext &Ctx);
33
34 /// Returns the stack node from an MIB metadata node.
35 MDNode *getMIBStackNode(const MDNode *MIB);
36
37 /// Returns the allocation type from an MIB metadata node.
38 AllocationType getMIBAllocType(const MDNode *MIB);
39
40 /// Class to build a trie of call stack contexts for a particular profiled
41 /// allocation call, along with their associated allocation types.
42 /// The allocation will be at the root of the trie, which is then used to
43 /// compute the minimum lists of context ids needed to associate a call context
44 /// with a single allocation type.
45 class CallStackTrie {
46 private:
47 struct CallStackTrieNode {
48 // Allocation types for call context sharing the context prefix at this
49 // node.
50 uint8_t AllocTypes;
51 // Map of caller stack id to the corresponding child Trie node.
52 std::map<uint64_t, CallStackTrieNode *> Callers;
CallStackTrieNodeCallStackTrieNode53 CallStackTrieNode(AllocationType Type)
54 : AllocTypes(static_cast<uint8_t>(Type)) {}
55 };
56
57 // The node for the allocation at the root.
58 CallStackTrieNode *Alloc;
59 // The allocation's leaf stack id.
60 uint64_t AllocStackId;
61
deleteTrieNode(CallStackTrieNode * Node)62 void deleteTrieNode(CallStackTrieNode *Node) {
63 if (!Node)
64 return;
65 for (auto C : Node->Callers)
66 deleteTrieNode(C.second);
67 delete Node;
68 }
69
70 // Recursive helper to trim contexts and create metadata nodes.
71 bool buildMIBNodes(CallStackTrieNode *Node, LLVMContext &Ctx,
72 std::vector<uint64_t> &MIBCallStack,
73 std::vector<Metadata *> &MIBNodes,
74 bool CalleeHasAmbiguousCallerContext);
75
76 public:
CallStackTrie()77 CallStackTrie() : Alloc(nullptr), AllocStackId(0) {}
~CallStackTrie()78 ~CallStackTrie() { deleteTrieNode(Alloc); }
79
empty()80 bool empty() const { return Alloc == nullptr; }
81
82 /// Add a call stack context with the given allocation type to the Trie.
83 /// The context is represented by the list of stack ids (computed during
84 /// matching via a debug location hash), expected to be in order from the
85 /// allocation call down to the bottom of the call stack (i.e. callee to
86 /// caller order).
87 void addCallStack(AllocationType AllocType, ArrayRef<uint64_t> StackIds);
88
89 /// Add the call stack context along with its allocation type from the MIB
90 /// metadata to the Trie.
91 void addCallStack(MDNode *MIB);
92
93 /// Build and attach the minimal necessary MIB metadata. If the alloc has a
94 /// single allocation type, add a function attribute instead. The reason for
95 /// adding an attribute in this case is that it matches how the behavior for
96 /// allocation calls will be communicated to lib call simplification after
97 /// cloning or another optimization to distinguish the allocation types,
98 /// which is lower overhead and more direct than maintaining this metadata.
99 /// Returns true if memprof metadata attached, false if not (attribute added).
100 bool buildAndAttachMIBMetadata(CallBase *CI);
101 };
102
103 /// Helper class to iterate through stack ids in both metadata (memprof MIB and
104 /// callsite) and the corresponding ThinLTO summary data structures
105 /// (CallsiteInfo and MIBInfo). This simplifies implementation of client code
106 /// which doesn't need to worry about whether we are operating with IR (Regular
107 /// LTO), or summary (ThinLTO).
108 template <class NodeT, class IteratorT> class CallStack {
109 public:
N(N)110 CallStack(const NodeT *N = nullptr) : N(N) {}
111
112 // Implement minimum required methods for range-based for loop.
113 // The default implementation assumes we are operating on ThinLTO data
114 // structures, which have a vector of StackIdIndices. There are specialized
115 // versions provided to iterate through metadata.
116 struct CallStackIterator {
117 const NodeT *N = nullptr;
118 IteratorT Iter;
119 CallStackIterator(const NodeT *N, bool End);
120 uint64_t operator*();
121 bool operator==(const CallStackIterator &rhs) { return Iter == rhs.Iter; }
122 bool operator!=(const CallStackIterator &rhs) { return !(*this == rhs); }
123 void operator++() { ++Iter; }
124 };
125
empty()126 bool empty() const { return N == nullptr; }
127
128 CallStackIterator begin() const;
end()129 CallStackIterator end() const { return CallStackIterator(N, /*End*/ true); }
130 CallStackIterator beginAfterSharedPrefix(CallStack &Other);
131
132 private:
133 const NodeT *N = nullptr;
134 };
135
136 template <class NodeT, class IteratorT>
CallStackIterator(const NodeT * N,bool End)137 CallStack<NodeT, IteratorT>::CallStackIterator::CallStackIterator(
138 const NodeT *N, bool End)
139 : N(N) {
140 if (!N)
141 return;
142 Iter = End ? N->StackIdIndices.end() : N->StackIdIndices.begin();
143 }
144
145 template <class NodeT, class IteratorT>
146 uint64_t CallStack<NodeT, IteratorT>::CallStackIterator::operator*() {
147 assert(Iter != N->StackIdIndices.end());
148 return *Iter;
149 }
150
151 template <class NodeT, class IteratorT>
152 typename CallStack<NodeT, IteratorT>::CallStackIterator
begin()153 CallStack<NodeT, IteratorT>::begin() const {
154 return CallStackIterator(N, /*End*/ false);
155 }
156
157 template <class NodeT, class IteratorT>
158 typename CallStack<NodeT, IteratorT>::CallStackIterator
beginAfterSharedPrefix(CallStack & Other)159 CallStack<NodeT, IteratorT>::beginAfterSharedPrefix(CallStack &Other) {
160 CallStackIterator Cur = begin();
161 for (CallStackIterator OtherCur = Other.begin();
162 Cur != end() && OtherCur != Other.end(); ++Cur, ++OtherCur)
163 assert(*Cur == *OtherCur);
164 return Cur;
165 }
166
167 /// Specializations for iterating through IR metadata stack contexts.
168 template <>
169 CallStack<MDNode, MDNode::op_iterator>::CallStackIterator::CallStackIterator(
170 const MDNode *N, bool End);
171 template <>
172 uint64_t CallStack<MDNode, MDNode::op_iterator>::CallStackIterator::operator*();
173
174 } // end namespace memprof
175 } // end namespace llvm
176
177 #endif
178