117 lines
4.2 KiB
C++
117 lines
4.2 KiB
C++
//===--------- DefineExternalSectionStartAndEndSymbols.h --------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Utility class for recognizing external section start and end symbols and
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// transforming them into defined symbols for the start and end blocks of the
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// associated Section.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_EXECUTIONENGINE_JITLINK_DEFINEEXTERNALSECTIONSTARTANDENDSYMBOLS_H
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#define LLVM_EXECUTIONENGINE_JITLINK_DEFINEEXTERNALSECTIONSTARTANDENDSYMBOLS_H
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#include "llvm/ExecutionEngine/JITLink/JITLink.h"
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#include "llvm/Support/Debug.h"
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#define DEBUG_TYPE "jitlink"
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namespace llvm {
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namespace jitlink {
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struct SectionRangeSymbolDesc {
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SectionRangeSymbolDesc() = default;
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SectionRangeSymbolDesc(Section &Sec, bool IsStart)
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: Sec(&Sec), IsStart(IsStart) {}
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Section *Sec = nullptr;
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bool IsStart = false;
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};
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/// Pass implementation for the createDefineExternalSectionStartAndEndSymbols
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/// function.
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template <typename SymbolIdentifierFunction>
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class DefineExternalSectionStartAndEndSymbols {
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public:
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DefineExternalSectionStartAndEndSymbols(SymbolIdentifierFunction F)
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: F(std::move(F)) {}
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Error operator()(LinkGraph &G) {
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// This pass will affect the external symbols set, so copy them out into a
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// vector and iterate over that.
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std::vector<Symbol *> Externals(G.external_symbols().begin(),
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G.external_symbols().end());
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for (auto *Sym : Externals) {
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SectionRangeSymbolDesc D = F(G, *Sym);
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if (D.Sec) {
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auto &SR = getSectionRange(*D.Sec);
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if (D.IsStart) {
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if (SR.empty())
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G.makeAbsolute(*Sym, orc::ExecutorAddr());
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else
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G.makeDefined(*Sym, *SR.getFirstBlock(), 0, 0, Linkage::Strong,
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Scope::Local, false);
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} else {
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if (SR.empty())
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G.makeAbsolute(*Sym, orc::ExecutorAddr());
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else
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G.makeDefined(*Sym, *SR.getLastBlock(),
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SR.getLastBlock()->getSize(), 0, Linkage::Strong,
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Scope::Local, false);
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}
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}
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}
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return Error::success();
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}
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private:
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SectionRange &getSectionRange(Section &Sec) {
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auto I = SectionRanges.find(&Sec);
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if (I == SectionRanges.end())
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I = SectionRanges.insert(std::make_pair(&Sec, SectionRange(Sec))).first;
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return I->second;
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}
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DenseMap<Section *, SectionRange> SectionRanges;
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SymbolIdentifierFunction F;
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};
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/// Returns a JITLink pass (as a function class) that uses the given symbol
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/// identification function to identify external section start and end symbols
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/// (and their associated Section*s) and transform the identified externals
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/// into defined symbols pointing to the start of the first block in the
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/// section and the end of the last (start and end symbols for empty sections
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/// will be transformed into absolute symbols at address 0).
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///
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/// The identification function should be callable as
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///
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/// SectionRangeSymbolDesc (LinkGraph &G, Symbol &Sym)
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///
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/// If Sym is not a section range start or end symbol then a default
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/// constructed SectionRangeSymbolDesc should be returned. If Sym is a start
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/// symbol then SectionRangeSymbolDesc(Sec, true), where Sec is a reference to
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/// the target Section. If Sym is an end symbol then
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/// SectionRangeSymbolDesc(Sec, false) should be returned.
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///
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/// This pass should be run in the PostAllocationPass pipeline, at which point
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/// all blocks should have been assigned their final addresses.
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template <typename SymbolIdentifierFunction>
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DefineExternalSectionStartAndEndSymbols<SymbolIdentifierFunction>
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createDefineExternalSectionStartAndEndSymbolsPass(
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SymbolIdentifierFunction &&F) {
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return DefineExternalSectionStartAndEndSymbols<SymbolIdentifierFunction>(
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std::forward<SymbolIdentifierFunction>(F));
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}
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} // end namespace jitlink
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} // end namespace llvm
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#undef DEBUG_TYPE
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#endif // LLVM_EXECUTIONENGINE_JITLINK_DEFINEEXTERNALSECTIONSTARTANDENDSYMBOLS_H
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