forked from OSchip/llvm-project
600 lines
25 KiB
C++
600 lines
25 KiB
C++
//===- UnwindInfoSection.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 "UnwindInfoSection.h"
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#include "ConcatOutputSection.h"
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#include "Config.h"
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#include "InputSection.h"
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#include "OutputSection.h"
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#include "OutputSegment.h"
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#include "SymbolTable.h"
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#include "Symbols.h"
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#include "SyntheticSections.h"
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#include "Target.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Memory.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/BinaryFormat/MachO.h"
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using namespace llvm;
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using namespace llvm::MachO;
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using namespace lld;
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using namespace lld::macho;
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#define COMMON_ENCODINGS_MAX 127
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#define COMPACT_ENCODINGS_MAX 256
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#define SECOND_LEVEL_PAGE_BYTES 4096
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#define SECOND_LEVEL_PAGE_WORDS (SECOND_LEVEL_PAGE_BYTES / sizeof(uint32_t))
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#define REGULAR_SECOND_LEVEL_ENTRIES_MAX \
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((SECOND_LEVEL_PAGE_BYTES - \
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sizeof(unwind_info_regular_second_level_page_header)) / \
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sizeof(unwind_info_regular_second_level_entry))
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#define COMPRESSED_SECOND_LEVEL_ENTRIES_MAX \
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((SECOND_LEVEL_PAGE_BYTES - \
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sizeof(unwind_info_compressed_second_level_page_header)) / \
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sizeof(uint32_t))
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#define COMPRESSED_ENTRY_FUNC_OFFSET_BITS 24
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#define COMPRESSED_ENTRY_FUNC_OFFSET_MASK \
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UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(~0)
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// Compact Unwind format is a Mach-O evolution of DWARF Unwind that
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// optimizes space and exception-time lookup. Most DWARF unwind
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// entries can be replaced with Compact Unwind entries, but the ones
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// that cannot are retained in DWARF form.
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//
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// This comment will address macro-level organization of the pre-link
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// and post-link compact unwind tables. For micro-level organization
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// pertaining to the bitfield layout of the 32-bit compact unwind
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// entries, see libunwind/include/mach-o/compact_unwind_encoding.h
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//
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// Important clarifying factoids:
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//
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// * __LD,__compact_unwind is the compact unwind format for compiler
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// output and linker input. It is never a final output. It could be
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// an intermediate output with the `-r` option which retains relocs.
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//
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// * __TEXT,__unwind_info is the compact unwind format for final
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// linker output. It is never an input.
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//
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// * __TEXT,__eh_frame is the DWARF format for both linker input and output.
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//
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// * __TEXT,__unwind_info entries are divided into 4 KiB pages (2nd
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// level) by ascending address, and the pages are referenced by an
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// index (1st level) in the section header.
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//
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// * Following the headers in __TEXT,__unwind_info, the bulk of the
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// section contains a vector of compact unwind entries
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// `{functionOffset, encoding}` sorted by ascending `functionOffset`.
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// Adjacent entries with the same encoding can be folded to great
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// advantage, achieving a 3-order-of-magnitude reduction in the
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// number of entries.
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//
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// * The __TEXT,__unwind_info format can accommodate up to 127 unique
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// encodings for the space-efficient compressed format. In practice,
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// fewer than a dozen unique encodings are used by C++ programs of
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// all sizes. Therefore, we don't even bother implementing the regular
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// non-compressed format. Time will tell if anyone in the field ever
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// overflows the 127-encodings limit.
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//
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// Refer to the definition of unwind_info_section_header in
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// compact_unwind_encoding.h for an overview of the format we are encoding
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// here.
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// TODO(gkm): prune __eh_frame entries superseded by __unwind_info, PR50410
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// TODO(gkm): how do we align the 2nd-level pages?
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using EncodingMap = llvm::DenseMap<compact_unwind_encoding_t, size_t>;
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struct SecondLevelPage {
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uint32_t kind;
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size_t entryIndex;
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size_t entryCount;
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size_t byteCount;
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std::vector<compact_unwind_encoding_t> localEncodings;
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EncodingMap localEncodingIndexes;
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};
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template <class Ptr> class UnwindInfoSectionImpl : public UnwindInfoSection {
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public:
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void prepareRelocations(ConcatInputSection *) override;
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void finalize() override;
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void writeTo(uint8_t *buf) const override;
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private:
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std::vector<std::pair<compact_unwind_encoding_t, size_t>> commonEncodings;
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EncodingMap commonEncodingIndexes;
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// Indices of personality functions within the GOT.
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std::vector<uint32_t> personalities;
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SmallDenseMap<std::pair<InputSection *, uint64_t /* addend */>, Symbol *>
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personalityTable;
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std::vector<unwind_info_section_header_lsda_index_entry> lsdaEntries;
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// Map of function offset (from the image base) to an index within the LSDA
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// array.
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llvm::DenseMap<uint32_t, uint32_t> functionToLsdaIndex;
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std::vector<CompactUnwindEntry<Ptr>> cuVector;
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std::vector<CompactUnwindEntry<Ptr> *> cuPtrVector;
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std::vector<SecondLevelPage> secondLevelPages;
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uint64_t level2PagesOffset = 0;
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};
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// Compact unwind relocations have different semantics, so we handle them in a
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// separate code path from regular relocations. First, we do not wish to add
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// rebase opcodes for __LD,__compact_unwind, because that section doesn't
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// actually end up in the final binary. Second, personality pointers always
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// reside in the GOT and must be treated specially.
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template <class Ptr>
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void UnwindInfoSectionImpl<Ptr>::prepareRelocations(ConcatInputSection *isec) {
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assert(isec->segname == segment_names::ld &&
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isec->name == section_names::compactUnwind);
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assert(!isec->shouldOmitFromOutput() &&
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"__compact_unwind section should not be omitted");
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// FIXME: Make this skip relocations for CompactUnwindEntries that
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// point to dead-stripped functions. That might save some amount of
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// work. But since there are usually just few personality functions
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// that are referenced from many places, at least some of them likely
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// live, it wouldn't reduce number of got entries.
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for (size_t i = 0; i < isec->relocs.size(); ++i) {
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Reloc &r = isec->relocs[i];
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assert(target->hasAttr(r.type, RelocAttrBits::UNSIGNED));
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if (r.offset % sizeof(CompactUnwindEntry<Ptr>) !=
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offsetof(CompactUnwindEntry<Ptr>, personality))
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continue;
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Reloc &rFunc = isec->relocs[++i];
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assert(r.offset ==
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rFunc.offset + offsetof(CompactUnwindEntry<Ptr>, personality));
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rFunc.referent.get<InputSection *>()->hasPersonality = true;
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if (auto *s = r.referent.dyn_cast<Symbol *>()) {
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if (auto *undefined = dyn_cast<Undefined>(s)) {
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treatUndefinedSymbol(*undefined);
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// treatUndefinedSymbol() can replace s with a DylibSymbol; re-check.
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if (isa<Undefined>(s))
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continue;
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}
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if (auto *defined = dyn_cast<Defined>(s)) {
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// Check if we have created a synthetic symbol at the same address.
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Symbol *&personality =
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personalityTable[{defined->isec, defined->value}];
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if (personality == nullptr) {
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personality = defined;
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in.got->addEntry(defined);
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} else if (personality != defined) {
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r.referent = personality;
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}
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continue;
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}
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assert(isa<DylibSymbol>(s));
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in.got->addEntry(s);
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continue;
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}
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if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
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assert(!isCoalescedWeak(referentIsec));
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// Personality functions can be referenced via section relocations
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// if they live in the same object file. Create placeholder synthetic
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// symbols for them in the GOT.
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Symbol *&s = personalityTable[{referentIsec, r.addend}];
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if (s == nullptr) {
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// This runs after dead stripping, so the noDeadStrip argument does not
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// matter.
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s = make<Defined>("<internal>", /*file=*/nullptr, referentIsec,
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r.addend, /*size=*/0, /*isWeakDef=*/false,
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/*isExternal=*/false, /*isPrivateExtern=*/false,
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/*isThumb=*/false, /*isReferencedDynamically=*/false,
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/*noDeadStrip=*/false);
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in.got->addEntry(s);
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}
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r.referent = s;
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r.addend = 0;
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}
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}
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}
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// Unwind info lives in __DATA, and finalization of __TEXT will occur before
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// finalization of __DATA. Moreover, the finalization of unwind info depends on
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// the exact addresses that it references. So it is safe for compact unwind to
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// reference addresses in __TEXT, but not addresses in any other segment.
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static ConcatInputSection *checkTextSegment(InputSection *isec) {
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if (isec->segname != segment_names::text)
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error("compact unwind references address in " + toString(isec) +
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" which is not in segment __TEXT");
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// __text should always be a ConcatInputSection.
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return cast<ConcatInputSection>(isec);
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}
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// We need to apply the relocations to the pre-link compact unwind section
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// before converting it to post-link form. There should only be absolute
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// relocations here: since we are not emitting the pre-link CU section, there
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// is no source address to make a relative location meaningful.
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template <class Ptr>
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static void
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relocateCompactUnwind(ConcatOutputSection *compactUnwindSection,
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std::vector<CompactUnwindEntry<Ptr>> &cuVector) {
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for (const ConcatInputSection *isec : compactUnwindSection->inputs) {
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assert(isec->parent == compactUnwindSection);
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uint8_t *buf =
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reinterpret_cast<uint8_t *>(cuVector.data()) + isec->outSecOff;
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memcpy(buf, isec->data.data(), isec->data.size());
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for (const Reloc &r : isec->relocs) {
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uint64_t referentVA = 0;
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if (auto *referentSym = r.referent.dyn_cast<Symbol *>()) {
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if (!isa<Undefined>(referentSym)) {
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assert(referentSym->isInGot());
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if (auto *defined = dyn_cast<Defined>(referentSym))
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checkTextSegment(defined->isec);
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// At this point in the link, we may not yet know the final address of
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// the GOT, so we just encode the index. We make it a 1-based index so
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// that we can distinguish the null pointer case.
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referentVA = referentSym->gotIndex + 1;
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}
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} else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
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ConcatInputSection *concatIsec = checkTextSegment(referentIsec);
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if (concatIsec->shouldOmitFromOutput())
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referentVA = UINT64_MAX; // Tombstone value
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else
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referentVA = referentIsec->getVA(r.addend);
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}
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writeAddress(buf + r.offset, referentVA, r.length);
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}
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}
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}
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// There should only be a handful of unique personality pointers, so we can
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// encode them as 2-bit indices into a small array.
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template <class Ptr>
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static void
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encodePersonalities(const std::vector<CompactUnwindEntry<Ptr> *> &cuPtrVector,
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std::vector<uint32_t> &personalities) {
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for (CompactUnwindEntry<Ptr> *cu : cuPtrVector) {
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if (cu->personality == 0)
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continue;
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// Linear search is fast enough for a small array.
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auto it = find(personalities, cu->personality);
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uint32_t personalityIndex; // 1-based index
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if (it != personalities.end()) {
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personalityIndex = std::distance(personalities.begin(), it) + 1;
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} else {
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personalities.push_back(cu->personality);
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personalityIndex = personalities.size();
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}
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cu->encoding |=
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personalityIndex << countTrailingZeros(
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static_cast<compact_unwind_encoding_t>(UNWIND_PERSONALITY_MASK));
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}
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if (personalities.size() > 3)
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error("too many personalities (" + std::to_string(personalities.size()) +
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") for compact unwind to encode");
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}
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// __unwind_info stores unwind data for address ranges. If several
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// adjacent functions have the same unwind encoding, LSDA, and personality
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// function, they share one unwind entry. For this to work, functions without
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// unwind info need explicit "no unwind info" unwind entries -- else the
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// unwinder would think they have the unwind info of the closest function
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// with unwind info right before in the image.
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template <class Ptr>
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static void addEntriesForFunctionsWithoutUnwindInfo(
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std::vector<CompactUnwindEntry<Ptr>> &cuVector) {
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DenseSet<Ptr> hasUnwindInfo;
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for (CompactUnwindEntry<Ptr> &cuEntry : cuVector)
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if (cuEntry.functionAddress != UINT64_MAX)
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hasUnwindInfo.insert(cuEntry.functionAddress);
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// Add explicit "has no unwind info" entries for all global and local symbols
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// without unwind info.
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auto markNoUnwindInfo = [&cuVector, &hasUnwindInfo](const Defined *d) {
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if (d->isLive() && isCodeSection(d->isec)) {
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Ptr ptr = d->getVA();
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if (!hasUnwindInfo.count(ptr))
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cuVector.push_back({ptr, 0, 0, 0, 0});
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}
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};
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for (Symbol *sym : symtab->getSymbols())
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if (auto *d = dyn_cast<Defined>(sym))
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markNoUnwindInfo(d);
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for (const InputFile *file : inputFiles)
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if (auto *objFile = dyn_cast<ObjFile>(file))
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for (Symbol *sym : objFile->symbols)
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if (auto *d = dyn_cast_or_null<Defined>(sym))
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if (!d->isExternal())
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markNoUnwindInfo(d);
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}
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// Scan the __LD,__compact_unwind entries and compute the space needs of
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// __TEXT,__unwind_info and __TEXT,__eh_frame
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template <class Ptr> void UnwindInfoSectionImpl<Ptr>::finalize() {
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if (compactUnwindSection == nullptr)
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return;
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// At this point, the address space for __TEXT,__text has been
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// assigned, so we can relocate the __LD,__compact_unwind entries
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// into a temporary buffer. Relocation is necessary in order to sort
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// the CU entries by function address. Sorting is necessary so that
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// we can fold adjacent CU entries with identical
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// encoding+personality+lsda. Folding is necessary because it reduces
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// the number of CU entries by as much as 3 orders of magnitude!
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compactUnwindSection->finalize();
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assert(compactUnwindSection->getSize() % sizeof(CompactUnwindEntry<Ptr>) ==
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0);
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size_t cuCount =
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compactUnwindSection->getSize() / sizeof(CompactUnwindEntry<Ptr>);
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cuVector.resize(cuCount);
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relocateCompactUnwind(compactUnwindSection, cuVector);
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addEntriesForFunctionsWithoutUnwindInfo(cuVector);
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// Rather than sort & fold the 32-byte entries directly, we create a
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// vector of pointers to entries and sort & fold that instead.
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cuPtrVector.reserve(cuCount);
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for (CompactUnwindEntry<Ptr> &cuEntry : cuVector)
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cuPtrVector.emplace_back(&cuEntry);
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llvm::sort(cuPtrVector, [](const CompactUnwindEntry<Ptr> *a,
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const CompactUnwindEntry<Ptr> *b) {
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return a->functionAddress < b->functionAddress;
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});
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// Dead-stripped functions get a functionAddress of UINT64_MAX in
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// relocateCompactUnwind(). Filter them out here.
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// FIXME: This doesn't yet collect associated data like LSDAs kept
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// alive only by a now-removed CompactUnwindEntry or other comdat-like
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// data (`kindNoneGroupSubordinate*` in ld64).
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CompactUnwindEntry<Ptr> tombstone;
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tombstone.functionAddress = static_cast<Ptr>(UINT64_MAX);
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cuPtrVector.erase(
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std::lower_bound(cuPtrVector.begin(), cuPtrVector.end(), &tombstone,
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[](const CompactUnwindEntry<Ptr> *a,
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const CompactUnwindEntry<Ptr> *b) {
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return a->functionAddress < b->functionAddress;
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}),
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cuPtrVector.end());
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// Fold adjacent entries with matching encoding+personality+lsda
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// We use three iterators on the same cuPtrVector to fold in-situ:
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// (1) `foldBegin` is the first of a potential sequence of matching entries
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// (2) `foldEnd` is the first non-matching entry after `foldBegin`.
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// The semi-open interval [ foldBegin .. foldEnd ) contains a range
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// entries that can be folded into a single entry and written to ...
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// (3) `foldWrite`
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auto foldWrite = cuPtrVector.begin();
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for (auto foldBegin = cuPtrVector.begin(); foldBegin < cuPtrVector.end();) {
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auto foldEnd = foldBegin;
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while (++foldEnd < cuPtrVector.end() &&
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(*foldBegin)->encoding == (*foldEnd)->encoding &&
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(*foldBegin)->personality == (*foldEnd)->personality &&
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(*foldBegin)->lsda == (*foldEnd)->lsda)
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;
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*foldWrite++ = *foldBegin;
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foldBegin = foldEnd;
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}
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cuPtrVector.erase(foldWrite, cuPtrVector.end());
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encodePersonalities(cuPtrVector, personalities);
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// Count frequencies of the folded encodings
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EncodingMap encodingFrequencies;
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for (const CompactUnwindEntry<Ptr> *cuPtrEntry : cuPtrVector)
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encodingFrequencies[cuPtrEntry->encoding]++;
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// Make a vector of encodings, sorted by descending frequency
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for (const auto &frequency : encodingFrequencies)
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commonEncodings.emplace_back(frequency);
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llvm::sort(commonEncodings,
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[](const std::pair<compact_unwind_encoding_t, size_t> &a,
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const std::pair<compact_unwind_encoding_t, size_t> &b) {
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if (a.second == b.second)
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// When frequencies match, secondarily sort on encoding
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// to maintain parity with validate-unwind-info.py
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return a.first > b.first;
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return a.second > b.second;
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});
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// Truncate the vector to 127 elements.
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// Common encoding indexes are limited to 0..126, while encoding
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// indexes 127..255 are local to each second-level page
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if (commonEncodings.size() > COMMON_ENCODINGS_MAX)
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commonEncodings.resize(COMMON_ENCODINGS_MAX);
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// Create a map from encoding to common-encoding-table index
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for (size_t i = 0; i < commonEncodings.size(); i++)
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commonEncodingIndexes[commonEncodings[i].first] = i;
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// Split folded encodings into pages, where each page is limited by ...
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// (a) 4 KiB capacity
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// (b) 24-bit difference between first & final function address
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// (c) 8-bit compact-encoding-table index,
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// for which 0..126 references the global common-encodings table,
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// and 127..255 references a local per-second-level-page table.
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// First we try the compact format and determine how many entries fit.
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// If more entries fit in the regular format, we use that.
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for (size_t i = 0; i < cuPtrVector.size();) {
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secondLevelPages.emplace_back();
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SecondLevelPage &page = secondLevelPages.back();
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page.entryIndex = i;
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uintptr_t functionAddressMax =
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cuPtrVector[i]->functionAddress + COMPRESSED_ENTRY_FUNC_OFFSET_MASK;
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size_t n = commonEncodings.size();
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size_t wordsRemaining =
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SECOND_LEVEL_PAGE_WORDS -
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sizeof(unwind_info_compressed_second_level_page_header) /
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sizeof(uint32_t);
|
|
while (wordsRemaining >= 1 && i < cuPtrVector.size()) {
|
|
const CompactUnwindEntry<Ptr> *cuPtr = cuPtrVector[i];
|
|
if (cuPtr->functionAddress >= functionAddressMax) {
|
|
break;
|
|
} else if (commonEncodingIndexes.count(cuPtr->encoding) ||
|
|
page.localEncodingIndexes.count(cuPtr->encoding)) {
|
|
i++;
|
|
wordsRemaining--;
|
|
} else if (wordsRemaining >= 2 && n < COMPACT_ENCODINGS_MAX) {
|
|
page.localEncodings.emplace_back(cuPtr->encoding);
|
|
page.localEncodingIndexes[cuPtr->encoding] = n++;
|
|
i++;
|
|
wordsRemaining -= 2;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
page.entryCount = i - page.entryIndex;
|
|
|
|
// If this is not the final page, see if it's possible to fit more
|
|
// entries by using the regular format. This can happen when there
|
|
// are many unique encodings, and we we saturated the local
|
|
// encoding table early.
|
|
if (i < cuPtrVector.size() &&
|
|
page.entryCount < REGULAR_SECOND_LEVEL_ENTRIES_MAX) {
|
|
page.kind = UNWIND_SECOND_LEVEL_REGULAR;
|
|
page.entryCount = std::min(REGULAR_SECOND_LEVEL_ENTRIES_MAX,
|
|
cuPtrVector.size() - page.entryIndex);
|
|
i = page.entryIndex + page.entryCount;
|
|
} else {
|
|
page.kind = UNWIND_SECOND_LEVEL_COMPRESSED;
|
|
}
|
|
}
|
|
|
|
for (const CompactUnwindEntry<Ptr> *cu : cuPtrVector) {
|
|
uint32_t functionOffset = cu->functionAddress - in.header->addr;
|
|
functionToLsdaIndex[functionOffset] = lsdaEntries.size();
|
|
if (cu->lsda != 0)
|
|
lsdaEntries.push_back(
|
|
{functionOffset, static_cast<uint32_t>(cu->lsda - in.header->addr)});
|
|
}
|
|
|
|
// compute size of __TEXT,__unwind_info section
|
|
level2PagesOffset =
|
|
sizeof(unwind_info_section_header) +
|
|
commonEncodings.size() * sizeof(uint32_t) +
|
|
personalities.size() * sizeof(uint32_t) +
|
|
// The extra second-level-page entry is for the sentinel
|
|
(secondLevelPages.size() + 1) *
|
|
sizeof(unwind_info_section_header_index_entry) +
|
|
lsdaEntries.size() * sizeof(unwind_info_section_header_lsda_index_entry);
|
|
unwindInfoSize =
|
|
level2PagesOffset + secondLevelPages.size() * SECOND_LEVEL_PAGE_BYTES;
|
|
}
|
|
|
|
// All inputs are relocated and output addresses are known, so write!
|
|
|
|
template <class Ptr>
|
|
void UnwindInfoSectionImpl<Ptr>::writeTo(uint8_t *buf) const {
|
|
// section header
|
|
auto *uip = reinterpret_cast<unwind_info_section_header *>(buf);
|
|
uip->version = 1;
|
|
uip->commonEncodingsArraySectionOffset = sizeof(unwind_info_section_header);
|
|
uip->commonEncodingsArrayCount = commonEncodings.size();
|
|
uip->personalityArraySectionOffset =
|
|
uip->commonEncodingsArraySectionOffset +
|
|
(uip->commonEncodingsArrayCount * sizeof(uint32_t));
|
|
uip->personalityArrayCount = personalities.size();
|
|
uip->indexSectionOffset = uip->personalityArraySectionOffset +
|
|
(uip->personalityArrayCount * sizeof(uint32_t));
|
|
uip->indexCount = secondLevelPages.size() + 1;
|
|
|
|
// Common encodings
|
|
auto *i32p = reinterpret_cast<uint32_t *>(&uip[1]);
|
|
for (const auto &encoding : commonEncodings)
|
|
*i32p++ = encoding.first;
|
|
|
|
// Personalities
|
|
for (const uint32_t &personality : personalities)
|
|
*i32p++ =
|
|
in.got->addr + (personality - 1) * target->wordSize - in.header->addr;
|
|
|
|
// Level-1 index
|
|
uint32_t lsdaOffset =
|
|
uip->indexSectionOffset +
|
|
uip->indexCount * sizeof(unwind_info_section_header_index_entry);
|
|
uint64_t l2PagesOffset = level2PagesOffset;
|
|
auto *iep = reinterpret_cast<unwind_info_section_header_index_entry *>(i32p);
|
|
for (const SecondLevelPage &page : secondLevelPages) {
|
|
iep->functionOffset =
|
|
cuPtrVector[page.entryIndex]->functionAddress - in.header->addr;
|
|
iep->secondLevelPagesSectionOffset = l2PagesOffset;
|
|
iep->lsdaIndexArraySectionOffset =
|
|
lsdaOffset + functionToLsdaIndex.lookup(iep->functionOffset) *
|
|
sizeof(unwind_info_section_header_lsda_index_entry);
|
|
iep++;
|
|
l2PagesOffset += SECOND_LEVEL_PAGE_BYTES;
|
|
}
|
|
// Level-1 sentinel
|
|
const CompactUnwindEntry<Ptr> &cuEnd = cuVector.back();
|
|
iep->functionOffset = cuEnd.functionAddress + cuEnd.functionLength;
|
|
iep->secondLevelPagesSectionOffset = 0;
|
|
iep->lsdaIndexArraySectionOffset =
|
|
lsdaOffset +
|
|
lsdaEntries.size() * sizeof(unwind_info_section_header_lsda_index_entry);
|
|
iep++;
|
|
|
|
// LSDAs
|
|
size_t lsdaBytes =
|
|
lsdaEntries.size() * sizeof(unwind_info_section_header_lsda_index_entry);
|
|
if (lsdaBytes > 0)
|
|
memcpy(iep, lsdaEntries.data(), lsdaBytes);
|
|
|
|
// Level-2 pages
|
|
auto *pp = reinterpret_cast<uint32_t *>(reinterpret_cast<uint8_t *>(iep) +
|
|
lsdaBytes);
|
|
for (const SecondLevelPage &page : secondLevelPages) {
|
|
if (page.kind == UNWIND_SECOND_LEVEL_COMPRESSED) {
|
|
uintptr_t functionAddressBase =
|
|
cuPtrVector[page.entryIndex]->functionAddress;
|
|
auto *p2p =
|
|
reinterpret_cast<unwind_info_compressed_second_level_page_header *>(
|
|
pp);
|
|
p2p->kind = page.kind;
|
|
p2p->entryPageOffset =
|
|
sizeof(unwind_info_compressed_second_level_page_header);
|
|
p2p->entryCount = page.entryCount;
|
|
p2p->encodingsPageOffset =
|
|
p2p->entryPageOffset + p2p->entryCount * sizeof(uint32_t);
|
|
p2p->encodingsCount = page.localEncodings.size();
|
|
auto *ep = reinterpret_cast<uint32_t *>(&p2p[1]);
|
|
for (size_t i = 0; i < page.entryCount; i++) {
|
|
const CompactUnwindEntry<Ptr> *cuep = cuPtrVector[page.entryIndex + i];
|
|
auto it = commonEncodingIndexes.find(cuep->encoding);
|
|
if (it == commonEncodingIndexes.end())
|
|
it = page.localEncodingIndexes.find(cuep->encoding);
|
|
*ep++ = (it->second << COMPRESSED_ENTRY_FUNC_OFFSET_BITS) |
|
|
(cuep->functionAddress - functionAddressBase);
|
|
}
|
|
if (page.localEncodings.size() != 0)
|
|
memcpy(ep, page.localEncodings.data(),
|
|
page.localEncodings.size() * sizeof(uint32_t));
|
|
} else {
|
|
auto *p2p =
|
|
reinterpret_cast<unwind_info_regular_second_level_page_header *>(pp);
|
|
p2p->kind = page.kind;
|
|
p2p->entryPageOffset =
|
|
sizeof(unwind_info_regular_second_level_page_header);
|
|
p2p->entryCount = page.entryCount;
|
|
auto *ep = reinterpret_cast<uint32_t *>(&p2p[1]);
|
|
for (size_t i = 0; i < page.entryCount; i++) {
|
|
const CompactUnwindEntry<Ptr> *cuep = cuPtrVector[page.entryIndex + i];
|
|
*ep++ = cuep->functionAddress;
|
|
*ep++ = cuep->encoding;
|
|
}
|
|
}
|
|
pp += SECOND_LEVEL_PAGE_WORDS;
|
|
}
|
|
}
|
|
|
|
UnwindInfoSection *macho::makeUnwindInfoSection() {
|
|
if (target->wordSize == 8)
|
|
return make<UnwindInfoSectionImpl<uint64_t>>();
|
|
else
|
|
return make<UnwindInfoSectionImpl<uint32_t>>();
|
|
}
|