Previously, the linker was ignoring the symbol of the R_GENERIC_NONE
relocation, so continue ignoring it. This is a little unfortunate because
it requires adding an extra condition on the fast path for relocation
handling.
I tried benchmarking this change, and I can't tell whether it has no
effect or is a regression of up to 1%. It might be possible to refactor
this code (e.g. do the lookup anyway, but avoid reporting an error), or by
changing the linker behavior, but this simple change gets the linker
working again.
Bug: http://b/147719203
Test: verify that the broken app works again
Change-Id: I7589b65705fec522d5fbadc05136dd5489833aea
Symbol lookup is O(L) where L is the number of libraries to search (e.g.
in the global and local lookup groups). Factor out the per-DSO work into
soinfo_do_lookup_impl, and optimize for the situation where all the DSOs
are using DT_GNU_HASH (rather than SysV hashes).
To load a set of libraries, the loader first constructs an auxiliary list
of libraries (SymbolLookupList, containing SymbolLookupLib objects). The
SymbolLookupList is reused for each DSO in a load group. (-Bsymbolic is
accommodated by modifying the SymbolLookupLib at the front of the list.)
To search for a symbol, soinfo_do_lookup_impl has a small loop that first
scans a vector of GNU bloom filters looking for a possible match.
There was a slight improvement from templatizing soinfo_do_lookup_impl
and skipping the does-this-DSO-lack-GNU-hash check.
Rewrite the relocation processing loop to be faster. There are specialized
functions that handle the expected relocation types in normal relocation
sections and in PLT relocation sections.
This CL can reduce the initial link time of large programs by around
40-50% (e.g. audioserver, cameraserver, etc). On the linker relocation
benchmark (64-bit walleye), it reduces the time from 131.6ms to 71.9ms.
Bug: http://b/143577578 (incidentally fixed by this CL)
Test: bionic-unit-tests
Change-Id: If40a42fb6ff566570f7280b71d58f7fa290b9343
