[llvm-dev] Making LLD PDB generation faster

Leonardo Santagada via llvm-dev llvm-dev at lists.llvm.org
Sat Feb 23 04:06:48 PST 2019


Is anyone working on making the PDB generation on LLD faster? Looking
of a trace for linking one of our binaries (it takes 1min6s-1min20s) I
see two things:

1) LookupBucketFor(Val, ConstFoundBucket); takes 35s so almost half of
the time of linking, mostly finding duplicates
2) There is no parallelization inside of addObjectsToPDB

Is anyone working on those? Also has anyone thought about merging .obj
files to deduplicate type infomation so we can do the linking on
projects to generate something like a lib file, but deduplicated debug
information (as far as I know actual .lib just put all pdbs or /Z7
debug info inside a file without dedup).

Just looking at the code it seems it is much more mature and also the
choice of SHA1_8 seems interesting (still don't know why not use

ps: My code to add ghashes to msvc compiled .obj files is almost ready
to be pushed as an option for llvm-objcopy.


Leonardo Santagada

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