From what I can tell, it's pretty similar to arm64. The two main differences
are:
1. No 64-bit relocations
2. Stub code writes to 32-bit registers instead of 64-bit
Plus of course the various on-disk structures like `segment_command` are using
the 32-bit instead of the 64-bit variants.
Reviewed By: #lld-macho, gkm
Differential Revision: https://reviews.llvm.org/D99822
From what I can tell, it's pretty similar to arm64. The two main differences
are:
1. No 64-bit relocations
2. Stub code writes to 32-bit registers instead of 64-bit
Plus of course the various on-disk structures like `segment_command` are using
the 32-bit instead of the 64-bit variants.
Reviewed By: #lld-macho, gkm
Differential Revision: https://reviews.llvm.org/D99822
The main challenge was handling the different on-disk structures (e.g.
`mach_header` vs `mach_header_64`). I tried to strike a balance between
sprinkling `target->wordSize == 8` checks everywhere (branchy = slow, and ugly)
and templatizing everything (causes code bloat, also ugly). I think I struck a
decent balance by judicious use of type erasure.
Note that LLD-ELF has a similar architecture, though it seems to use more templating.
Linking chromium_framework takes about the same time before and after this
change:
N Min Max Median Avg Stddev
x 20 4.52 4.67 4.595 4.5945 0.044423204
+ 20 4.5 4.71 4.575 4.582 0.056344803
No difference proven at 95.0% confidence
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D99633
My test refactoring in D80217 seems to have caused yaml2obj to emit
unaligned nlist_64 structs, causing ASAN'd lld to be unhappy. I don't
think this is an issue with yaml2obj though -- llvm-mc also seems to
emit unaligned nlist_64s. This diff makes lld able to safely do aligned
reads under ASAN builds while hopefully creating no overhead for regular
builds on architectures that support unaligned reads.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D80414
Jez Ng