a3f67f0920
Linker optimization hints mark a sequence of instructions used for synthesizing an address, like ADRP+ADD. If the referenced symbol ends up close enough, it can be replaced by a faster sequence of instructions like ADR+NOP. This commit adds support for 2 of the 7 defined ARM64 optimization hints: - LOH_ARM64_ADRP_ADD, which transforms a pair of ADRP+ADD into ADR+NOP if the referenced address is within +/- 1 MiB - LOH_ARM64_ADRP_ADRP, which transforms two ADRP instructions into ADR+NOP if they reference the same page These two kinds already cover more than 50% of all LOHs in chromium_framework. Differential Review: https://reviews.llvm.org/D128093
131 lines
4.1 KiB
C++
131 lines
4.1 KiB
C++
//===- Relocations.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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#ifndef LLD_MACHO_RELOCATIONS_H
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#define LLD_MACHO_RELOCATIONS_H
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#include "llvm/ADT/BitmaskEnum.h"
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#include "llvm/ADT/PointerUnion.h"
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#include "llvm/BinaryFormat/MachO.h"
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#include "llvm/Support/Endian.h"
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#include <cstddef>
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#include <cstdint>
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namespace lld {
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namespace macho {
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LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
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class Symbol;
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class InputSection;
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enum class RelocAttrBits {
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_0 = 0, // invalid
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PCREL = 1 << 0, // Value is PC-relative offset
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ABSOLUTE = 1 << 1, // Value is an absolute address or fixed offset
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BYTE4 = 1 << 2, // 4 byte datum
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BYTE8 = 1 << 3, // 8 byte datum
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EXTERN = 1 << 4, // Can have an external symbol
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LOCAL = 1 << 5, // Can have a local symbol
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ADDEND = 1 << 6, // *_ADDEND paired prefix reloc
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SUBTRAHEND = 1 << 7, // *_SUBTRACTOR paired prefix reloc
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BRANCH = 1 << 8, // Value is branch target
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GOT = 1 << 9, // References a symbol in the Global Offset Table
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TLV = 1 << 10, // References a thread-local symbol
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LOAD = 1 << 11, // Relaxable indirect load
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POINTER = 1 << 12, // Non-relaxable indirect load (pointer is taken)
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UNSIGNED = 1 << 13, // *_UNSIGNED relocs
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LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue*/ (1 << 14) - 1),
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};
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// Note: SUBTRACTOR always pairs with UNSIGNED (a delta between two symbols).
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struct RelocAttrs {
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llvm::StringRef name;
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RelocAttrBits bits;
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bool hasAttr(RelocAttrBits b) const { return (bits & b) == b; }
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};
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struct Reloc {
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uint8_t type = llvm::MachO::GENERIC_RELOC_INVALID;
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bool pcrel = false;
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uint8_t length = 0;
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// The offset from the start of the subsection that this relocation belongs
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// to.
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uint32_t offset = 0;
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// Adding this offset to the address of the referent symbol or subsection
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// gives the destination that this relocation refers to.
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int64_t addend = 0;
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llvm::PointerUnion<Symbol *, InputSection *> referent = nullptr;
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Reloc() = default;
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Reloc(uint8_t type, bool pcrel, uint8_t length, uint32_t offset,
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int64_t addend, llvm::PointerUnion<Symbol *, InputSection *> referent)
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: type(type), pcrel(pcrel), length(length), offset(offset),
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addend(addend), referent(referent) {}
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};
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struct OptimizationHint {
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// Offset of the first address within the containing InputSection.
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uint64_t offset0;
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// Offset of the other addresses relative to the first one.
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int16_t delta[2];
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uint8_t type;
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};
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bool validateSymbolRelocation(const Symbol *, const InputSection *,
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const Reloc &);
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/*
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* v: The value the relocation is attempting to encode
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* bits: The number of bits actually available to encode this relocation
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*/
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void reportRangeError(void *loc, const Reloc &, const llvm::Twine &v,
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uint8_t bits, int64_t min, uint64_t max);
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struct SymbolDiagnostic {
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const Symbol *symbol;
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llvm::StringRef reason;
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};
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void reportRangeError(void *loc, SymbolDiagnostic, const llvm::Twine &v,
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uint8_t bits, int64_t min, uint64_t max);
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template <typename Diagnostic>
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inline void checkInt(void *loc, Diagnostic d, int64_t v, int bits) {
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if (v != llvm::SignExtend64(v, bits))
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reportRangeError(loc, d, llvm::Twine(v), bits, llvm::minIntN(bits),
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llvm::maxIntN(bits));
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}
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template <typename Diagnostic>
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inline void checkUInt(void *loc, Diagnostic d, uint64_t v, int bits) {
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if ((v >> bits) != 0)
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reportRangeError(loc, d, llvm::Twine(v), bits, 0, llvm::maxUIntN(bits));
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}
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inline void writeAddress(uint8_t *loc, uint64_t addr, uint8_t length) {
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switch (length) {
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case 2:
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llvm::support::endian::write32le(loc, addr);
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break;
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case 3:
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llvm::support::endian::write64le(loc, addr);
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break;
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default:
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llvm_unreachable("invalid r_length");
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}
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}
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extern const RelocAttrs invalidRelocAttrs;
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} // namespace macho
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} // namespace lld
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#endif
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