Their addresses are already encoded as section-relative offsets, so
there's no need to rebase them at runtime. {D85080} has some context
on the weirdness of TLV sections.
Fixes llvm.org/PR48491.
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D93257
Symbols of the same type must be laid out contiguously: following ld64's
lead, we choose to emit all local symbols first, then external symbols,
and finally undefined symbols. For each symbol type, the LC_DYSYMTAB
load command will record the range (start index and total number) of
those symbols in the symbol table.
This work was motivated by the fact that LLDB won't search for debug
info if LC_DYSYMTAB says there are no local symbols (since STABS symbols
are all local symbols). With this change, LLDB is now able to display
the source lines at a given breakpoint when debugging our binaries.
Some tests had to be updated due to local symbol names now appearing in
`llvm-objdump`'s output.
Reviewed By: #lld-macho, smeenai, clayborg
Differential Revision: https://reviews.llvm.org/D89285
Note: What ELF refers to as "TLS", Mach-O seems to refer to as "TLV", i.e.
thread-local variables.
This diff implements support for TLV relocations that reference defined
symbols. On x86_64, TLV relocations are always used with movq opcodes, so for
defined TLVs, we don't need to create a synthetic section to store the
addresses of the symbols -- we can just convert the `movq` to a `leaq`.
One notable quirk of Mach-O's TLVs is that absolute-address relocations
inside TLV-defining sections behave differently -- their addresses are
no longer absolute, but relative to the start of the target section.
(AFAICT, RIP-relative relocations are not allowed in these sections.)
Reviewed By: #lld-macho, compnerd, smeenai
Differential Revision: https://reviews.llvm.org/D85080
Jez Ng