[RISCV] Fix mgather -> riscv.masked.strided.load combine not extending indices (...
[llvm-project.git] / llvm / lib / Analysis / ScopedNoAliasAA.cpp
blob3815bdf49d59cea4eac0d7a54ebc3b563916479d
1 //===- ScopedNoAliasAA.cpp - Scoped No-Alias Alias Analysis ---------------===//
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 defines the ScopedNoAlias alias-analysis pass, which implements
10 // metadata-based scoped no-alias support.
12 // Alias-analysis scopes are defined by an id (which can be a string or some
13 // other metadata node), a domain node, and an optional descriptive string.
14 // A domain is defined by an id (which can be a string or some other metadata
15 // node), and an optional descriptive string.
17 // !dom0 = metadata !{ metadata !"domain of foo()" }
18 // !scope1 = metadata !{ metadata !scope1, metadata !dom0, metadata !"scope 1" }
19 // !scope2 = metadata !{ metadata !scope2, metadata !dom0, metadata !"scope 2" }
21 // Loads and stores can be tagged with an alias-analysis scope, and also, with
22 // a noalias tag for a specific scope:
24 // ... = load %ptr1, !alias.scope !{ !scope1 }
25 // ... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 }
27 // When evaluating an aliasing query, if one of the instructions is associated
28 // has a set of noalias scopes in some domain that is a superset of the alias
29 // scopes in that domain of some other instruction, then the two memory
30 // accesses are assumed not to alias.
32 //===----------------------------------------------------------------------===//
34 #include "llvm/Analysis/ScopedNoAliasAA.h"
35 #include "llvm/ADT/SetOperations.h"
36 #include "llvm/ADT/SmallPtrSet.h"
37 #include "llvm/Analysis/MemoryLocation.h"
38 #include "llvm/IR/InstrTypes.h"
39 #include "llvm/IR/LLVMContext.h"
40 #include "llvm/IR/Metadata.h"
41 #include "llvm/InitializePasses.h"
42 #include "llvm/Pass.h"
43 #include "llvm/Support/Casting.h"
44 #include "llvm/Support/CommandLine.h"
46 using namespace llvm;
48 // A handy option for disabling scoped no-alias functionality. The same effect
49 // can also be achieved by stripping the associated metadata tags from IR, but
50 // this option is sometimes more convenient.
51 static cl::opt<bool> EnableScopedNoAlias("enable-scoped-noalias",
52 cl::init(true), cl::Hidden);
54 AliasResult ScopedNoAliasAAResult::alias(const MemoryLocation &LocA,
55 const MemoryLocation &LocB,
56 AAQueryInfo &AAQI,
57 const Instruction *) {
58 if (!EnableScopedNoAlias)
59 return AliasResult::MayAlias;
61 // Get the attached MDNodes.
62 const MDNode *AScopes = LocA.AATags.Scope, *BScopes = LocB.AATags.Scope;
64 const MDNode *ANoAlias = LocA.AATags.NoAlias, *BNoAlias = LocB.AATags.NoAlias;
66 if (!mayAliasInScopes(AScopes, BNoAlias))
67 return AliasResult::NoAlias;
69 if (!mayAliasInScopes(BScopes, ANoAlias))
70 return AliasResult::NoAlias;
72 return AliasResult::MayAlias;
75 ModRefInfo ScopedNoAliasAAResult::getModRefInfo(const CallBase *Call,
76 const MemoryLocation &Loc,
77 AAQueryInfo &AAQI) {
78 if (!EnableScopedNoAlias)
79 return ModRefInfo::ModRef;
81 if (!mayAliasInScopes(Loc.AATags.Scope,
82 Call->getMetadata(LLVMContext::MD_noalias)))
83 return ModRefInfo::NoModRef;
85 if (!mayAliasInScopes(Call->getMetadata(LLVMContext::MD_alias_scope),
86 Loc.AATags.NoAlias))
87 return ModRefInfo::NoModRef;
89 return ModRefInfo::ModRef;
92 ModRefInfo ScopedNoAliasAAResult::getModRefInfo(const CallBase *Call1,
93 const CallBase *Call2,
94 AAQueryInfo &AAQI) {
95 if (!EnableScopedNoAlias)
96 return ModRefInfo::ModRef;
98 if (!mayAliasInScopes(Call1->getMetadata(LLVMContext::MD_alias_scope),
99 Call2->getMetadata(LLVMContext::MD_noalias)))
100 return ModRefInfo::NoModRef;
102 if (!mayAliasInScopes(Call2->getMetadata(LLVMContext::MD_alias_scope),
103 Call1->getMetadata(LLVMContext::MD_noalias)))
104 return ModRefInfo::NoModRef;
106 return ModRefInfo::ModRef;
109 static void collectMDInDomain(const MDNode *List, const MDNode *Domain,
110 SmallPtrSetImpl<const MDNode *> &Nodes) {
111 for (const MDOperand &MDOp : List->operands())
112 if (const MDNode *MD = dyn_cast<MDNode>(MDOp))
113 if (AliasScopeNode(MD).getDomain() == Domain)
114 Nodes.insert(MD);
117 bool ScopedNoAliasAAResult::mayAliasInScopes(const MDNode *Scopes,
118 const MDNode *NoAlias) const {
119 if (!Scopes || !NoAlias)
120 return true;
122 // Collect the set of scope domains relevant to the noalias scopes.
123 SmallPtrSet<const MDNode *, 16> Domains;
124 for (const MDOperand &MDOp : NoAlias->operands())
125 if (const MDNode *NAMD = dyn_cast<MDNode>(MDOp))
126 if (const MDNode *Domain = AliasScopeNode(NAMD).getDomain())
127 Domains.insert(Domain);
129 // We alias unless, for some domain, the set of noalias scopes in that domain
130 // is a superset of the set of alias scopes in that domain.
131 for (const MDNode *Domain : Domains) {
132 SmallPtrSet<const MDNode *, 16> ScopeNodes;
133 collectMDInDomain(Scopes, Domain, ScopeNodes);
134 if (ScopeNodes.empty())
135 continue;
137 SmallPtrSet<const MDNode *, 16> NANodes;
138 collectMDInDomain(NoAlias, Domain, NANodes);
140 // To not alias, all of the nodes in ScopeNodes must be in NANodes.
141 if (llvm::set_is_subset(ScopeNodes, NANodes))
142 return false;
145 return true;
148 AnalysisKey ScopedNoAliasAA::Key;
150 ScopedNoAliasAAResult ScopedNoAliasAA::run(Function &F,
151 FunctionAnalysisManager &AM) {
152 return ScopedNoAliasAAResult();
155 char ScopedNoAliasAAWrapperPass::ID = 0;
157 INITIALIZE_PASS(ScopedNoAliasAAWrapperPass, "scoped-noalias-aa",
158 "Scoped NoAlias Alias Analysis", false, true)
160 ImmutablePass *llvm::createScopedNoAliasAAWrapperPass() {
161 return new ScopedNoAliasAAWrapperPass();
164 ScopedNoAliasAAWrapperPass::ScopedNoAliasAAWrapperPass() : ImmutablePass(ID) {
165 initializeScopedNoAliasAAWrapperPassPass(*PassRegistry::getPassRegistry());
168 bool ScopedNoAliasAAWrapperPass::doInitialization(Module &M) {
169 Result.reset(new ScopedNoAliasAAResult());
170 return false;
173 bool ScopedNoAliasAAWrapperPass::doFinalization(Module &M) {
174 Result.reset();
175 return false;
178 void ScopedNoAliasAAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
179 AU.setPreservesAll();