This could probably have been part of D99633, but I split it up to make
things a bit more reviewable. I also fixed some bugs in the implementation that
were masked through integer underflows when operating in 64-bit mode.
Reviewed By: #lld-macho, gkm
Differential Revision: https://reviews.llvm.org/D99823
This could probably have been part of D99633, but I split it up to make
things a bit more reviewable. I also fixed some bugs in the implementation that
were masked through integer underflows when operating in 64-bit mode.
Reviewed By: #lld-macho, gkm
Differential Revision: https://reviews.llvm.org/D99823
The LSDA pointers are encoded as offsets from the image base,
and arranged in one big contiguous array. Each second-level page records
the offset within that LSDA array which corresponds to the LSDA for its
first CU entry.
Reviewed By: clayborg
Differential Revision: https://reviews.llvm.org/D95810
Note that there is a triple indirection involved with
personalities and compact unwind:
1. Two bits of each CU encoding are used as an offset into the
personality array.
2. Each entry of the personality array is an offset from the image base.
The resulting address (after adding the image base) should point within the
GOT.
3. The corresponding GOT entry contains the actual pointer to the
personality function.
To further complicate things, when the personality function is in the
object file (as opposed to a dylib), its references in
`__compact_unwind` may refer to it via a section + offset relocation
instead of a symbol relocation. Since our GOT implementation can only
create entries for symbols, we have to create a synthetic symbol at the
given section offset.
Reviewed By: clayborg
Differential Revision: https://reviews.llvm.org/D95809
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
Digest the input `__LD,__compact_unwind` and produce the output `__TEXT,__unwind_info`. This is the initial commit with the major functionality.
Successor commits will add handling for ...
* `__TEXT,__eh_frame`
* personalities & LSDA
* `-r` pass-through
Differential Revision: https://reviews.llvm.org/D86805
Jez Ng