[PATCH] D43978: Write a hash of the binary as the PE Debug Directory Timestamp

Shoaib Meenai via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Mar 1 20:57:05 PST 2018

smeenai added a comment.

In https://reviews.llvm.org/D43978#1024843, @zturner wrote:

> In https://reviews.llvm.org/D43978#1024841, @smeenai wrote:
> > "Hash the PDB"
> >
> > I thought hashing the PDB itself was considered undesirable for speed reasons (since PDBs can get pretty large)? Or is xxHash64 fast enough that it doesn't matter?
> I haven't timed it (probably should).  But, if we want reproducible builds, I dont' know of a better option.

If it turns out that the hashing is really expensive, perhaps there could be an option to just use an actual timestamp or something, for people who care about link speed more than reproducibility?

Do you know how link.exe handles this? I know they're doing some sort of hashing for their timestamps, but I thought it was just based on the output binary, not its PDB.


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