Handle overflow beyond the 127 common encodings limit
The common encodings table holds only 127 entries. The encodings index for compact entries is 8 bits wide, and indexes 127..255 are stored locally to each second-level page. Prior to this diff, lld would `fatal()` if encodings overflowed the 127 limit.
This diff populates a per-second-level-page encodings table as needed. When the per-page encodings table hits its limit, we must terminate the page. If such early termination would consume fewer entries than a regular (non-compact) encoding page, then we prefer the regular format.
Caveat: one reason the common-encoding table might overflow is because of DWARF debug-info references, which are not yet implemented and will come with a later diff.
Differential Revision: https://reviews.llvm.org/D93267
diff --git a/lld/MachO/UnwindInfoSection.h b/lld/MachO/UnwindInfoSection.h
index 61e639d..2285cf9 100644
--- a/lld/MachO/UnwindInfoSection.h
+++ b/lld/MachO/UnwindInfoSection.h
@@ -49,35 +49,30 @@
compactUnwindSection = cuSection;
}
+ using EncodingMap = llvm::DenseMap<compact_unwind_encoding_t, size_t>;
+
+ struct SecondLevelPage {
+ uint32_t kind;
+ size_t entryIndex;
+ size_t entryCount;
+ size_t byteCount;
+ std::vector<compact_unwind_encoding_t> localEncodings;
+ EncodingMap localEncodingIndexes;
+ };
+
private:
std::vector<std::pair<compact_unwind_encoding_t, size_t>> commonEncodings;
+ EncodingMap commonEncodingIndexes;
std::vector<uint32_t> personalities;
std::vector<unwind_info_section_header_lsda_index_entry> lsdaEntries;
std::vector<CompactUnwindEntry64> cuVector;
std::vector<const CompactUnwindEntry64 *> cuPtrVector;
- std::vector<std::vector<const CompactUnwindEntry64 *>::const_iterator>
- pageBounds;
+ std::vector<SecondLevelPage> secondLevelPages;
MergedOutputSection *compactUnwindSection = nullptr;
uint64_t level2PagesOffset = 0;
uint64_t unwindInfoSize = 0;
};
-#define UNWIND_INFO_COMMON_ENCODINGS_MAX 127
-
-#define UNWIND_INFO_SECOND_LEVEL_PAGE_SIZE 4096
-#define UNWIND_INFO_REGULAR_SECOND_LEVEL_ENTRIES_MAX \
- ((UNWIND_INFO_SECOND_LEVEL_PAGE_SIZE - \
- sizeof(unwind_info_regular_second_level_page_header)) / \
- sizeof(unwind_info_regular_second_level_entry))
-#define UNWIND_INFO_COMPRESSED_SECOND_LEVEL_ENTRIES_MAX \
- ((UNWIND_INFO_SECOND_LEVEL_PAGE_SIZE - \
- sizeof(unwind_info_compressed_second_level_page_header)) / \
- sizeof(uint32_t))
-
-#define UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET_BITS 24
-#define UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET_MASK \
- UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(~0)
-
} // namespace macho
} // namespace lld
