Thanks Brandon, I checked the strace log and before the error is written, there's a log entry: openat(AT_FDCWD, "_build/stage1/libraries/ghc-prim/build/GHC/Types.hi", O_RDONLY|O_NOCTTY|O_NONBLOCK) = -1 ENOENT (No such file or directory) So it looks like GHC is indeed looking at the correct hi path, not the doubled path. On Wed, Sep 16, 2020 at 9:03 PM Brandon Allbery wrote:

Without looking at the implementation, it looks to me like the filename is doubled for some reason. This may suggest places to look.

On Wed, Sep 16, 2020 at 2:57 PM Cheng Shao wrote:

...

Hi all,

Following a short chat in #ghc last week, I did a first attempt of reusing existing Iface logic to implement serialization for codegen-related Core. The implementation is included in the attached patch (~100 loc). As a quick and dirty validation of whether it works, I also modified the codegen pipeline logic to do a roundtrip: after CorePrep, the Core bits are converted to Iface, then we immediately convert it back and use it for later compiling.

With the patch applied, stage-1 GHC would produce a "missing hi file" error like:

: Bad interface file: _build/stage1/libraries/ghc-prim/build/GHC/Types.hi _build/stage1/libraries/ghc-prim/build/GHC/Types.hi: openBinaryFile: does not exist (No such file or directory)

The error surprises me, since by the time we perform the Core-to-Core roundtrip, the .hi file should already have been written to disk. Is there anything obviously wrong with the implementation? I'd appreciate any pointers or further questions, thanks a lot!

Best regards, Cheng _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

-- brandon s allbery kf8nh allbery.b@gmail.com

Hi Ben, The -ddump-if-trace output is attached here. The error is produced when compiling GHC.Types in ghc-prim.

Note that interface files are written after the Core pipeline is run.

Sorry for the confusion, I didn't mean the Core simplifier pipeline. I mean the "Core -> Iface -> Core" roundtrip I tried to perform using the output of CorePrep. By the time we do CorePrep, the hi files should already have been written. On Wed, Sep 16, 2020 at 11:48 PM Ben Gamari wrote:

Cheng Shao writes:

...

Hi all,

Following a short chat in #ghc last week, I did a first attempt of reusing existing Iface logic to implement serialization for codegen-related Core. The implementation is included in the attached patch (~100 loc). As a quick and dirty validation of whether it works, I also modified the codegen pipeline logic to do a roundtrip: after CorePrep, the Core bits are converted to Iface, then we immediately convert it back and use it for later compiling.

With the patch applied, stage-1 GHC would produce a "missing hi file" error like:

: Bad interface file: _build/stage1/libraries/ghc-prim/build/GHC/Types.hi _build/stage1/libraries/ghc-prim/build/GHC/Types.hi: openBinaryFile: does not exist (No such file or directory)

Hi Cheng,

Which module is being compiled when this error is produced? Could you provide -ddump-if-trace output for the failing compilation?

...

The error surprises me, since by the time we perform the Core-to-Core roundtrip, the .hi file should already have been written to disk. Is there anything obviously wrong with the implementation? I'd appreciate any pointers or further questions, thanks a lot!

Note that interface files are written after the Core pipeline is run.

Cheers,

- Ben