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path: root/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
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* [JITLink][MachO] Fix common symbol size plumbing.Lang Hames2019-12-191-1/+1
| | | | This fixes the underlying bug that was exposed by 298e183e813.
* [ORC][JITLink] Add support for weak references, and improve handling of staticLang Hames2019-11-281-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | libraries. This patch substantially updates ORCv2's lookup API in order to support weak references, and to better support static archives. Key changes: -- Each symbol being looked for is now associated with a SymbolLookupFlags value. If the associated value is SymbolLookupFlags::RequiredSymbol then the symbol must be defined in one of the JITDylibs being searched (or be able to be generated in one of these JITDylibs via an attached definition generator) or the lookup will fail with an error. If the associated value is SymbolLookupFlags::WeaklyReferencedSymbol then the symbol is permitted to be undefined, in which case it will simply not appear in the resulting SymbolMap if the rest of the lookup succeeds. Since lookup now requires these flags for each symbol, the lookup method now takes an instance of a new SymbolLookupSet type rather than a SymbolNameSet. SymbolLookupSet is a vector-backed set of (name, flags) pairs. Clients are responsible for ensuring that the set property (i.e. unique elements) holds, though this is usually simple and SymbolLookupSet provides convenience methods to support this. -- Lookups now have an associated LookupKind value, which is either LookupKind::Static or LookupKind::DLSym. Definition generators can inspect the lookup kind when determining whether or not to generate new definitions. The StaticLibraryDefinitionGenerator is updated to only pull in new objects from the archive if the lookup kind is Static. This allows lookup to be re-used to emulate dlsym for JIT'd symbols without pulling in new objects from archives (which would not happen in a normal dlsym call). -- JITLink is updated to allow externals to be assigned weak linkage, and weak externals now use the SymbolLookupFlags::WeaklyReferencedSymbol value for lookups. Unresolved weak references will be assigned the default value of zero. Since this patch was modifying the lookup API anyway, it alo replaces all of the "MatchNonExported" boolean arguments with a "JITDylibLookupFlags" enum for readability. If a JITDylib's associated value is JITDylibLookupFlags::MatchExportedSymbolsOnly then the lookup will only match against exported (non-hidden) symbols in that JITDylib. If a JITDylib's associated value is JITDylibLookupFlags::MatchAllSymbols then the lookup will match against any symbol defined in the JITDylib.
* [JITLink] Tighten section sorting criteria to fix a flaky test case.Lang Hames2019-10-281-1/+3
| | | | | | | | | | Sections may have zero size and zero-sized sections may share a start address with other zero-sized sections. For the section overlap test to function correctly zero-sized sections must be ordered before any non-zero sized ones. This should fix the intermittent failures in the test/ExecutionEngine/JITLink/X86/MachO_zero_fill_alignment.s test case that have been observed on some builders.
* Fix MSVC "result of 32-bit shift implicitly converted to 64 bits" warning. NFCI.Simon Pilgrim2019-10-041-1/+1
| | | | llvm-svn: 373729
* [JITLink] Switch from an atom-based model to a "blocks and symbols" model.Lang Hames2019-10-041-0/+535
In the Atom model the symbols, content and relocations of a relocatable object file are represented as a graph of atoms, where each Atom represents a contiguous block of content with a single name (or no name at all if the content is anonymous), and where edges between Atoms represent relocations. If more than one symbol is associated with a contiguous block of content then the content is broken into multiple atoms and layout constraints (represented by edges) are introduced to ensure that the content remains effectively contiguous. These layout constraints must be kept in mind when examining the content associated with a symbol (it may be spread over multiple atoms) or when applying certain relocation types (e.g. MachO subtractors). This patch replaces the Atom model in JITLink with a blocks-and-symbols model. The blocks-and-symbols model represents relocatable object files as bipartite graphs, with one set of nodes representing contiguous content (Blocks) and another representing named or anonymous locations (Symbols) within a Block. Relocations are represented as edges from Blocks to Symbols. This scheme removes layout constraints (simplifying handling of MachO alt-entry symbols, and hopefully ELF sections at some point in the future) and simplifies some relocation logic. llvm-svn: 373689
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