forked from OSchip/llvm-project
87 lines
2.9 KiB
C++
87 lines
2.9 KiB
C++
//===- Relocations.cpp ----------------------------------------------------===//
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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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#include "Relocations.h"
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#include "InputChunks.h"
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#include "SyntheticSections.h"
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using namespace llvm;
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using namespace llvm::wasm;
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using namespace lld;
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using namespace lld::wasm;
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static bool requiresGOTAccess(const Symbol *Sym) {
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return Config->Pic && !Sym->isHidden() && !Sym->isLocal();
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}
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void lld::wasm::scanRelocations(InputChunk *Chunk) {
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if (!Chunk->Live)
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return;
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ObjFile *File = Chunk->File;
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ArrayRef<WasmSignature> Types = File->getWasmObj()->types();
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for (const WasmRelocation &Reloc : Chunk->getRelocations()) {
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if (Reloc.Type == R_WASM_TYPE_INDEX_LEB) {
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// Mark target type as live
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File->TypeMap[Reloc.Index] =
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Out.TypeSec->registerType(Types[Reloc.Index]);
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File->TypeIsUsed[Reloc.Index] = true;
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continue;
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}
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// Other relocation types all have a corresponding symbol
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Symbol *Sym = File->getSymbols()[Reloc.Index];
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switch (Reloc.Type) {
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case R_WASM_TABLE_INDEX_I32:
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case R_WASM_TABLE_INDEX_SLEB:
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case R_WASM_TABLE_INDEX_REL_SLEB:
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if (requiresGOTAccess(Sym))
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break;
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Out.ElemSec->addEntry(cast<FunctionSymbol>(Sym));
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break;
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case R_WASM_GLOBAL_INDEX_LEB:
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if (!isa<GlobalSymbol>(Sym))
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Out.ImportSec->addGOTEntry(Sym);
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break;
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case R_WASM_MEMORY_ADDR_SLEB:
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case R_WASM_MEMORY_ADDR_LEB:
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case R_WASM_MEMORY_ADDR_REL_SLEB:
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if (!Config->Relocatable && Sym->isUndefined() && !Sym->isWeak()) {
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error(toString(File) + ": cannot resolve relocation of type " +
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relocTypeToString(Reloc.Type) +
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" against undefined (non-weak) data symbol: " + toString(*Sym));
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}
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break;
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}
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if (Config->Pic) {
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switch (Reloc.Type) {
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case R_WASM_TABLE_INDEX_SLEB:
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case R_WASM_MEMORY_ADDR_SLEB:
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case R_WASM_MEMORY_ADDR_LEB:
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// Certain relocation types can't be used when building PIC output,
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// since they would require absolute symbol addresses at link time.
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error(toString(File) + ": relocation " + relocTypeToString(Reloc.Type) +
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" cannot be used againt symbol " + toString(*Sym) +
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"; recompile with -fPIC");
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break;
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case R_WASM_TABLE_INDEX_I32:
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case R_WASM_MEMORY_ADDR_I32:
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// These relocation types are only present in the data section and
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// will be converted into code by `generateRelocationCode`. This code
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// requires the symbols to have GOT entires.
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if (requiresGOTAccess(Sym))
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Out.ImportSec->addGOTEntry(Sym);
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break;
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}
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}
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}
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}
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