Today, we always take into account the possibility that object files
produced by MC may be consumed by an incremental linker. This results
in us initialing fields which vary with time (TimeDateStamp) which harms
hermetic builds (e.g. verifying a self-host went well) and produces
sub-optimal code because we cannot assume anything about the relative
position of functions within a section (call sites can get redirected
through incremental linker thunks).
Let's provide an MCTargetOption which controls this behavior so that we
can disable this functionality if we know a-priori that the build will
not rely on /incremental.
llvm-svn: 256203
It's O(N^2) because it does a simple walk through the existing types to
find duplicates, but that will be fixed in a follow-up commit to use a
mapping data structure of some kind.
llvm-svn: 255482
This is a preliminary change towards deduplicating type units based on
their signatures. Next change will skip emission of types when their
signature has already been seen.
llvm-svn: 255154
This probably shouldn't be generated in the .dwo file for CUs, only for
TUs, but it's in the sample .dwos (generated by clang) so dwp should
reflect that.
Arguably the DWP tool could be smart enough to know that the CUs
shouldn't need a debug_line.dwo section and skip that even when it's
legitimately generated for TUs, but that's a bit more off-book.
llvm-svn: 254767
This is very rudimentary support for debug_cu_index, but it is enough to
allow llvm-dwarfdump to find the offsets for contributions and
correctly dump debug_info.
It will need to actually find the real signature of the unit and build
the real hash table with the right number of buckets, as per the DWP
specification.
It will also need to be expanded to cover the tu_index as well.
llvm-svn: 254489
This doesn't deduplicate strings in the debug_str section, nor does it
properly wire up the index so that debug_info can /find/ these strings,
but it does correct the str_offsets specifically.
Follow up patches to address those related/next issues.
llvm-svn: 254431
This just concatenates the common DWP sections without doing any of the
fancy DWP things like:
1) update str_offsets
2) deduplicating strings
3) merging/creating cu/tu_index
Patches for these will follow shortly.
(also not sure about target triple/object file type for this tool - do I
really need a whole triple just to write an object file that contains
purely static/hardcoded bytes in each section? & I guess I should just
pick it based on the first input, maybe, rather than hardcoding for now
- but we only produce .dwo on ELF platforms with objcopy for now anyway)
llvm-svn: 254355
David Majnemer