[clang] D41416: [modules] [pch] Do not deserialize all lazy template specializations when looking for one. (PR #83108)

[Vassil Vassilev via cfe-commits]

vgvassilev wrote:

> Personally I feel this patch is good and the testing result from our workload shows it is good too. But it looks like the performance testing results from google @zygoloid @ilya-biryukov is not good. So maybe we need to wait for landing this. (It will be great if @ilya-biryukov would like to test again)

Thanks for putting this up. I was planning to do so, however, locally I got:

```
  Clang :: CXX/module/basic/basic.link/p2.cppm
  Clang :: Driver/clang_f_opts.c
  Clang :: Driver/darwin-header-search-libcxx.cpp
  Clang :: Index/crash-recovery-modules.m
  Clang :: Modules/ExtDebugInfo.cpp
  Clang :: Modules/cxx-templates.cpp
  Clang :: Modules/odr_hash.cpp
  Clang :: Modules/using-directive-redecl.cpp
  Clang :: Modules/using-directive.cpp
  Clang :: PCH/chain-late-anonymous-namespace.cpp
  Clang :: PCH/cxx-namespaces.cpp
  Clang :: PCH/namespaces.cpp
```

I believe some tests require just adjusting the reference files, but others may need some debugging.

https://github.com/llvm/llvm-project/pull/83108