This adds partial support for weak functions to the CompileOnDemandLayer by
modifying the addLogicalModule method to check for existing stub definitions
before building a new stub for a weak function. This scheme is sufficient to
support ODR definitions, but fails for general weak definitions if strong
definition is encountered after the first weak definition. (A more extensive
refactor will be required to fully support weak symbols).
This patch does *not* add weak symbol support to RuntimeDyld: I hope to add
that in the near future.
llvm-svn: 277896
This patch replaces RuntimeDyld::SymbolInfo with JITSymbol: A symbol class
that is capable of lazy materialization (i.e. the symbol definition needn't be
emitted until the address is requested). This can be used to support common
and weak symbols in the JIT (though this is not implemented in this patch).
For consistency, RuntimeDyld::SymbolResolver is renamed to JITSymbolResolver.
For space efficiency a new class, JITEvaluatedSymbol, is introduced that
behaves like the old RuntimeDyld::SymbolInfo - i.e. it is just a pair of an
address and symbol flags. Instances of JITEvaluatedSymbol can be used in
symbol-tables to avoid paying the space cost of the materializer.
llvm-svn: 277386
