1 //===- LLVMContextImpl.cpp - Implement LLVMContextImpl --------------------===//
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 implements the opaque LLVMContextImpl.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "LLVMContextImpl.h"
14 #include "llvm/ADT/SetVector.h"
15 #include "llvm/IR/Module.h"
16 #include "llvm/IR/OptBisect.h"
17 #include "llvm/IR/Type.h"
18 #include "llvm/Support/ManagedStatic.h"
19 #include <cassert>
20 #include <utility>
21 
22 using namespace llvm;
23 
24 LLVMContextImpl::LLVMContextImpl(LLVMContext &C)
25   : DiagHandler(std::make_unique<DiagnosticHandler>()),
26     VoidTy(C, Type::VoidTyID),
27     LabelTy(C, Type::LabelTyID),
28     HalfTy(C, Type::HalfTyID),
29     BFloatTy(C, Type::BFloatTyID),
30     FloatTy(C, Type::FloatTyID),
31     DoubleTy(C, Type::DoubleTyID),
32     MetadataTy(C, Type::MetadataTyID),
33     TokenTy(C, Type::TokenTyID),
34     X86_FP80Ty(C, Type::X86_FP80TyID),
35     FP128Ty(C, Type::FP128TyID),
36     PPC_FP128Ty(C, Type::PPC_FP128TyID),
37     X86_MMXTy(C, Type::X86_MMXTyID),
38     Int1Ty(C, 1),
39     Int8Ty(C, 8),
40     Int16Ty(C, 16),
41     Int32Ty(C, 32),
42     Int64Ty(C, 64),
43     Int128Ty(C, 128) {}
44 
45 LLVMContextImpl::~LLVMContextImpl() {
46   // NOTE: We need to delete the contents of OwnedModules, but Module's dtor
47   // will call LLVMContextImpl::removeModule, thus invalidating iterators into
48   // the container. Avoid iterators during this operation:
49   while (!OwnedModules.empty())
50     delete *OwnedModules.begin();
51 
52 #ifndef NDEBUG
53   // Check for metadata references from leaked Instructions.
54   for (auto &Pair : InstructionMetadata)
55     Pair.first->dump();
56   assert(InstructionMetadata.empty() &&
57          "Instructions with metadata have been leaked");
58 #endif
59 
60   // Drop references for MDNodes.  Do this before Values get deleted to avoid
61   // unnecessary RAUW when nodes are still unresolved.
62   for (auto *I : DistinctMDNodes)
63     I->dropAllReferences();
64 #define HANDLE_MDNODE_LEAF_UNIQUABLE(CLASS)                                    \
65   for (auto *I : CLASS##s)                                                     \
66     I->dropAllReferences();
67 #include "llvm/IR/Metadata.def"
68 
69   // Also drop references that come from the Value bridges.
70   for (auto &Pair : ValuesAsMetadata)
71     Pair.second->dropUsers();
72   for (auto &Pair : MetadataAsValues)
73     Pair.second->dropUse();
74 
75   // Destroy MDNodes.
76   for (MDNode *I : DistinctMDNodes)
77     I->deleteAsSubclass();
78 #define HANDLE_MDNODE_LEAF_UNIQUABLE(CLASS)                                    \
79   for (CLASS * I : CLASS##s)                                                   \
80     delete I;
81 #include "llvm/IR/Metadata.def"
82 
83   // Free the constants.
84   for (auto *I : ExprConstants)
85     I->dropAllReferences();
86   for (auto *I : ArrayConstants)
87     I->dropAllReferences();
88   for (auto *I : StructConstants)
89     I->dropAllReferences();
90   for (auto *I : VectorConstants)
91     I->dropAllReferences();
92   ExprConstants.freeConstants();
93   ArrayConstants.freeConstants();
94   StructConstants.freeConstants();
95   VectorConstants.freeConstants();
96   InlineAsms.freeConstants();
97 
98   CAZConstants.clear();
99   CPNConstants.clear();
100   UVConstants.clear();
101   IntConstants.clear();
102   FPConstants.clear();
103 
104   for (auto &CDSConstant : CDSConstants)
105     delete CDSConstant.second;
106   CDSConstants.clear();
107 
108   // Destroy attribute node lists.
109   for (FoldingSetIterator<AttributeSetNode> I = AttrsSetNodes.begin(),
110          E = AttrsSetNodes.end(); I != E; ) {
111     FoldingSetIterator<AttributeSetNode> Elem = I++;
112     delete &*Elem;
113   }
114 
115   // Destroy MetadataAsValues.
116   {
117     SmallVector<MetadataAsValue *, 8> MDVs;
118     MDVs.reserve(MetadataAsValues.size());
119     for (auto &Pair : MetadataAsValues)
120       MDVs.push_back(Pair.second);
121     MetadataAsValues.clear();
122     for (auto *V : MDVs)
123       delete V;
124   }
125 
126   // Destroy ValuesAsMetadata.
127   for (auto &Pair : ValuesAsMetadata)
128     delete Pair.second;
129 }
130 
131 void LLVMContextImpl::dropTriviallyDeadConstantArrays() {
132   SmallSetVector<ConstantArray *, 4> WorkList;
133 
134   // When ArrayConstants are of substantial size and only a few in them are
135   // dead, starting WorkList with all elements of ArrayConstants can be
136   // wasteful. Instead, starting WorkList with only elements that have empty
137   // uses.
138   for (ConstantArray *C : ArrayConstants)
139     if (C->use_empty())
140       WorkList.insert(C);
141 
142   while (!WorkList.empty()) {
143     ConstantArray *C = WorkList.pop_back_val();
144     if (C->use_empty()) {
145       for (const Use &Op : C->operands()) {
146         if (auto *COp = dyn_cast<ConstantArray>(Op))
147           WorkList.insert(COp);
148       }
149       C->destroyConstant();
150     }
151   }
152 }
153 
154 void Module::dropTriviallyDeadConstantArrays() {
155   Context.pImpl->dropTriviallyDeadConstantArrays();
156 }
157 
158 namespace llvm {
159 
160 /// Make MDOperand transparent for hashing.
161 ///
162 /// This overload of an implementation detail of the hashing library makes
163 /// MDOperand hash to the same value as a \a Metadata pointer.
164 ///
165 /// Note that overloading \a hash_value() as follows:
166 ///
167 /// \code
168 ///     size_t hash_value(const MDOperand &X) { return hash_value(X.get()); }
169 /// \endcode
170 ///
171 /// does not cause MDOperand to be transparent.  In particular, a bare pointer
172 /// doesn't get hashed before it's combined, whereas \a MDOperand would.
173 static const Metadata *get_hashable_data(const MDOperand &X) { return X.get(); }
174 
175 } // end namespace llvm
176 
177 unsigned MDNodeOpsKey::calculateHash(MDNode *N, unsigned Offset) {
178   unsigned Hash = hash_combine_range(N->op_begin() + Offset, N->op_end());
179 #ifndef NDEBUG
180   {
181     SmallVector<Metadata *, 8> MDs(N->op_begin() + Offset, N->op_end());
182     unsigned RawHash = calculateHash(MDs);
183     assert(Hash == RawHash &&
184            "Expected hash of MDOperand to equal hash of Metadata*");
185   }
186 #endif
187   return Hash;
188 }
189 
190 unsigned MDNodeOpsKey::calculateHash(ArrayRef<Metadata *> Ops) {
191   return hash_combine_range(Ops.begin(), Ops.end());
192 }
193 
194 StringMapEntry<uint32_t> *LLVMContextImpl::getOrInsertBundleTag(StringRef Tag) {
195   uint32_t NewIdx = BundleTagCache.size();
196   return &*(BundleTagCache.insert(std::make_pair(Tag, NewIdx)).first);
197 }
198 
199 void LLVMContextImpl::getOperandBundleTags(SmallVectorImpl<StringRef> &Tags) const {
200   Tags.resize(BundleTagCache.size());
201   for (const auto &T : BundleTagCache)
202     Tags[T.second] = T.first();
203 }
204 
205 uint32_t LLVMContextImpl::getOperandBundleTagID(StringRef Tag) const {
206   auto I = BundleTagCache.find(Tag);
207   assert(I != BundleTagCache.end() && "Unknown tag!");
208   return I->second;
209 }
210 
211 SyncScope::ID LLVMContextImpl::getOrInsertSyncScopeID(StringRef SSN) {
212   auto NewSSID = SSC.size();
213   assert(NewSSID < std::numeric_limits<SyncScope::ID>::max() &&
214          "Hit the maximum number of synchronization scopes allowed!");
215   return SSC.insert(std::make_pair(SSN, SyncScope::ID(NewSSID))).first->second;
216 }
217 
218 void LLVMContextImpl::getSyncScopeNames(
219     SmallVectorImpl<StringRef> &SSNs) const {
220   SSNs.resize(SSC.size());
221   for (const auto &SSE : SSC)
222     SSNs[SSE.second] = SSE.first();
223 }
224 
225 /// Singleton instance of the OptBisect class.
226 ///
227 /// This singleton is accessed via the LLVMContext::getOptPassGate() function.
228 /// It provides a mechanism to disable passes and individual optimizations at
229 /// compile time based on a command line option (-opt-bisect-limit) in order to
230 /// perform a bisecting search for optimization-related problems.
231 ///
232 /// Even if multiple LLVMContext objects are created, they will all return the
233 /// same instance of OptBisect in order to provide a single bisect count.  Any
234 /// code that uses the OptBisect object should be serialized when bisection is
235 /// enabled in order to enable a consistent bisect count.
236 static ManagedStatic<OptBisect> OptBisector;
237 
238 OptPassGate &LLVMContextImpl::getOptPassGate() const {
239   if (!OPG)
240     OPG = &(*OptBisector);
241   return *OPG;
242 }
243 
244 void LLVMContextImpl::setOptPassGate(OptPassGate& OPG) {
245   this->OPG = &OPG;
246 }
247