This adds support for generating Chrome-tracing .json profile traces in the LLD COFF driver. Also add the necessary time scopes, so that the profile trace shows in great detail which tasks are executed. As an example, this is what we see when linking a Unreal Engine executable: 
In order to reduce noise for a MR.
Bail early if there is no existing output file to be overwritten. Differential Revision: https://reviews.llvm.org/D83272
On Windows co-operative programs can be expected to open LLD's output in FILE_SHARE_DELETE mode. This allows us to delete the file (by moving it to a temporary filename and then deleting it) so that we can link another output file that overwrites the existing file, even if the current file is in use. A similar strategy is documented here: https://boostgsoc13.github.io/boost.afio/doc/html/afio/FAQ/deleting_open_files.html Differential Revision: https://reviews.llvm.org/D82567
Essentially takes the lld/Common/Threads.h wrappers and moves them to the llvm/Support/Paralle.h algorithm header. The changes are: - Remove policy parameter, since all clients use `par`. - Rename the methods to `parallelSort` etc to match LLVM style, since they are no longer C++17 pstl compatible. - Move algorithms from llvm::parallel:: to llvm::, since they have "parallel" in the name and are no longer overloads of the regular algorithms. - Add range overloads - Use the sequential algorithm directly when 1 thread is requested (skips task grouping) - Fix the index type of parallelForEachN to size_t. Nobody in LLVM was using any other parameter, and it made overload resolution hard for for_each_n(par, 0, foo.size(), ...) because 0 is int, not size_t. Remove Threads.h and update LLD for that. This is a prerequisite for parallel public symbol processing in the PDB library, which is in LLVM. Reviewed By: MaskRay, aganea Differential Revision: https://reviews.llvm.org/D79390
--no-threads is a name copied from gold.
gold has --no-thread, --thread-count and several other --thread-count-*.
There are needs to customize the number of threads (running several lld
processes concurrently or customizing the number of LTO threads).
Having a single --threads=N is a straightforward replacement of gold's
--no-threads + --thread-count.
--no-threads is used rarely. So just delete --no-threads instead of
keeping it for compatibility for a while.
If --threads= is specified (ELF,wasm; COFF /threads: is similar),
--thinlto-jobs= defaults to --threads=,
otherwise all available hardware threads are used.
There is currently no way to override a --threads={1,2,...}. It is still
a debate whether we should use --threads=all.
Reviewed By: rnk, aganea
Differential Revision: https://reviews.llvm.org/D76885
Reviewed By: ruiu, MaskRay Differential Revision: https://reviews.llvm.org/D72196
llvm-svn: 365732
This patch does the same thing as r365595 to other subdirectories, which completes the naming style change for the entire lld directory. With this, the naming style conversion is complete for lld. Differential Revision: https://reviews.llvm.org/D64473 llvm-svn: 365730