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 = "$__stub_ptr";
21} // namespace
22
23void JITLinkRedirectableSymbolManager::emitRedirectableSymbols(
24 std::unique_ptr<MaterializationResponsibility> R, SymbolMap InitialDests) {
25
26 auto &ES = ObjLinkingLayer.getExecutionSession();
27 auto G = std::make_unique<jitlink::LinkGraph>(
28 args: ("<indirect stubs graph #" + Twine(++StubGraphIdx) + ">").str(),
29 args: ES.getSymbolStringPool(), args: ES.getTargetTriple(),
30 args: ES.getTargetTriple().getArchPointerBitWidth() / 8, args: SubtargetFeatures(),
31 args&: jitlink::getGenericEdgeKindName);
32 auto &PointerSection =
33 G->createSection(Name: StubPtrSectionName, Prot: MemProt::Write | MemProt::Read);
34 auto &StubsSection =
35 G->createSection(Name: JumpStubSectionName, Prot: MemProt::Exec | MemProt::Read);
36
37 SymbolFlagsMap NewSymbols;
38 for (auto &[Name, Def] : InitialDests) {
39 jitlink::Symbol *TargetSym = nullptr;
40 if (Def.getAddress())
41 TargetSym = &G->addAbsoluteSymbol(
42 Name: G->allocateName(Source: *Name + "$__init_tgt"), Address: Def.getAddress(), Size: 0,
43 L: jitlink::Linkage::Strong, S: jitlink::Scope::Local, IsLive: false);
44
45 auto PtrName = ES.intern(SymName: (*Name + StubSuffix).str());
46 auto &Ptr = AnonymousPtrCreator(*G, PointerSection, TargetSym, 0);
47 Ptr.setName(PtrName);
48 Ptr.setScope(jitlink::Scope::Hidden);
49 auto &Stub = PtrJumpStubCreator(*G, StubsSection, Ptr);
50 Stub.setName(Name);
51 Stub.setScope(Def.getFlags().isExported() ? jitlink::Scope::Default
52 : jitlink::Scope::Hidden);
53 Stub.setLinkage(!Def.getFlags().isWeak() ? jitlink::Linkage::Strong
54 : jitlink::Linkage::Weak);
55 NewSymbols[std::move(PtrName)] = JITSymbolFlags();
56 }
57
58 // Try to claim responsibility for the new stub symbols.
59 if (auto Err = R->defineMaterializing(SymbolFlags: std::move(NewSymbols))) {
60 ES.reportError(Err: std::move(Err));
61 return R->failMaterialization();
62 }
63
64 ObjLinkingLayer.emit(R: std::move(R), G: std::move(G));
65}
66
67Error JITLinkRedirectableSymbolManager::redirect(JITDylib &JD,
68 const SymbolMap &NewDests) {
69 auto &ES = ObjLinkingLayer.getExecutionSession();
70 SymbolLookupSet LS;
71 DenseMap<NonOwningSymbolStringPtr, SymbolStringPtr> PtrToStub;
72 for (auto &[StubName, Sym] : NewDests) {
73 auto PtrName = ES.intern(SymName: (*StubName + StubSuffix).str());
74 PtrToStub[NonOwningSymbolStringPtr(PtrName)] = StubName;
75 LS.add(Name: std::move(PtrName));
76 }
77 auto PtrSyms =
78 ES.lookup(SearchOrder: {{&JD, JITDylibLookupFlags::MatchAllSymbols}}, Symbols: std::move(LS));
79 if (!PtrSyms)
80 return PtrSyms.takeError();
81
82 std::vector<tpctypes::PointerWrite> PtrWrites;
83 for (auto &[PtrName, PtrSym] : *PtrSyms) {
84 auto DestSymI = NewDests.find(Val: PtrToStub[NonOwningSymbolStringPtr(PtrName)]);
85 assert(DestSymI != NewDests.end() && "Bad ptr -> stub mapping");
86 auto &DestSym = DestSymI->second;
87 PtrWrites.push_back(x: {PtrSym.getAddress(), DestSym.getAddress()});
88 }
89
90 return MemAccess.writePointers(Ws: PtrWrites);
91}
92