1//===-- JITLinkRedirectableSymbolManager.cpp - JITLink redirection in Orc -===//
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#include "llvm/ExecutionEngine/Orc/JITLinkRedirectableSymbolManager.h"
10#include "llvm/ExecutionEngine/Orc/Core.h"
11
12#define DEBUG_TYPE "orc"
13
14using namespace llvm;
15using namespace llvm::orc;
16
17namespace {
18constexpr StringRef JumpStubSectionName = "__orc_stubs";
19constexpr StringRef StubPtrSectionName = "__orc_stub_ptrs";
20constexpr StringRef StubSuffix = "$__stub_ptr";
21} // namespace
22
23void JITLinkRedirectableSymbolManager::emitRedirectableSymbols(
24 std::unique_ptr<MaterializationResponsibility> R, SymbolMap InitialDests) {
25
26 auto &ES = ObjLinkingLayer.getExecutionSession();
27 auto G = std::make_unique<jitlink::LinkGraph>(
28 args: ("<indirect stubs graph #" + Twine(++StubGraphIdx) + ">").str(),
29 args: ES.getSymbolStringPool(), args: ES.getTargetTriple(), args: SubtargetFeatures(),
30 args&: jitlink::getGenericEdgeKindName);
31 auto &PointerSection =
32 G->createSection(Name: StubPtrSectionName, Prot: MemProt::Write | MemProt::Read);
33 auto &StubsSection =
34 G->createSection(Name: JumpStubSectionName, Prot: MemProt::Exec | MemProt::Read);
35
36 SymbolFlagsMap NewSymbols;
37 for (auto &[Name, Def] : InitialDests) {
38 jitlink::Symbol *TargetSym = nullptr;
39 if (Def.getAddress())
40 TargetSym = &G->addAbsoluteSymbol(
41 Name: G->allocateName(Source: *Name + "$__init_tgt"), Address: Def.getAddress(), Size: 0,
42 L: jitlink::Linkage::Strong, S: jitlink::Scope::Local, IsLive: false);
43
44 auto PtrName = ES.intern(SymName: (*Name + StubSuffix).str());
45 auto &Ptr = AnonymousPtrCreator(*G, PointerSection, TargetSym, 0);
46 Ptr.setName(PtrName);
47 Ptr.setScope(jitlink::Scope::Hidden);
48 auto &Stub = PtrJumpStubCreator(*G, StubsSection, Ptr);
49 Stub.setName(Name);
50 Stub.setScope(Def.getFlags().isExported() ? jitlink::Scope::Default
51 : jitlink::Scope::Hidden);
52 Stub.setLinkage(!Def.getFlags().isWeak() ? jitlink::Linkage::Strong
53 : jitlink::Linkage::Weak);
54 NewSymbols[std::move(PtrName)] = JITSymbolFlags();
55 }
56
57 // Try to claim responsibility for the new stub symbols.
58 if (auto Err = R->defineMaterializing(SymbolFlags: std::move(NewSymbols))) {
59 ES.reportError(Err: std::move(Err));
60 return R->failMaterialization();
61 }
62
63 ObjLinkingLayer.emit(R: std::move(R), G: std::move(G));
64}
65
66Error JITLinkRedirectableSymbolManager::redirect(JITDylib &JD,
67 const SymbolMap &NewDests) {
68 auto &ES = ObjLinkingLayer.getExecutionSession();
69 SymbolLookupSet LS;
70 DenseMap<NonOwningSymbolStringPtr, SymbolStringPtr> PtrToStub;
71 for (auto &[StubName, Sym] : NewDests) {
72 auto PtrName = ES.intern(SymName: (*StubName + StubSuffix).str());
73 PtrToStub[NonOwningSymbolStringPtr(PtrName)] = StubName;
74 LS.add(Name: std::move(PtrName));
75 }
76 auto PtrSyms =
77 ES.lookup(SearchOrder: {{&JD, JITDylibLookupFlags::MatchAllSymbols}}, Symbols: std::move(LS));
78 if (!PtrSyms)
79 return PtrSyms.takeError();
80
81 std::vector<tpctypes::PointerWrite> PtrWrites;
82 for (auto &[PtrName, PtrSym] : *PtrSyms) {
83 auto DestSymI = NewDests.find(Val: PtrToStub[NonOwningSymbolStringPtr(PtrName)]);
84 assert(DestSymI != NewDests.end() && "Bad ptr -> stub mapping");
85 auto &DestSym = DestSymI->second;
86 PtrWrites.push_back(x: {PtrSym.getAddress(), DestSym.getAddress()});
87 }
88
89 return ObjLinkingLayer.getExecutionSession()
90 .getExecutorProcessControl()
91 .getMemoryAccess()
92 .writePointers(Ws: PtrWrites);
93}
94