Backport instructions

hadrian.settings

stage1.*.ghc.hs.opts += -finfo-table-map -fdistinct-constructor-tables          
stage1.ghc-bin.ghc.link.opts += -eventlog                                                  

instructions.md

These instructions will tell you how to build 8.10.2 with the -hi, -finfo-table-map and -fdistinct-constructor-tables patch backported.

GHC Branch: https://gitlab.haskell.org/mpickering/ghc/-/commits/ghc-con-info-backport

Building GHC

1. mkdir _build, Copy the hadrian.settings file into _build.
2. git submodule update --init
3. perl boot
4. ./configure
5. ./hadrian/build.cabal.sh -j4

You will now have an instrumented version of GHC which has support for the -hi mode, -finfo-table-map and -fdistinct-constructor-tables flags.

Building graphql-engine

1. Modify the cabal.project file in the package * stanza to build dependencies with -finfo-table-map and -fdistinct-constructor-tables.
2. Modify graphql-engine.cabal by adding -eventlog to ghc-options.
3. Remove specific 8.10.2 bounds from cabal.project.freeze.
4. Modify RUN_INVOCATION to pass -hi -l-au
5. Start server normally, the resulting eventlog ends up in the server/ directory.

Viewing the profile

If you wish to view the profile, use eventlog2html. This is still very rough so it might not be so easy to understand what's going on.

https://github.com/mpickering/eventlog2html/tree/wip/profile-info-table

Building GHC worked for me, after switching to 8.6.5, thanks!

Built graphql-engine successfully. I just added the following lines to cabal.project but I assume changing the path should work fine too:

with-compiler: /path/to/ghc/_build/stage1/bin/ghc
with-hc-pkg: /path/to/ghc/_build/stage1/bin/ghc-pkg

Do the same instructions (and branch) apply if you want to do this with GHC 8.10.4? For example, would attempting to merge con-info-backport to the ghc-8.10 be one way?

In any case, thanks so much for putting this together!

@m4c4p You can try rebasing I suppose? I don't think the backport is based on exactly the 8.10.2 commit.

After adding your fork as a remote (git remote add mpickering https://gitlab.haskell.org/mpickering/ghc), I was able to merge this branch into ghc's 8.10 branch and build successfully. Thanks for the great work!