WIP: GCC with separated runtime libraries #132343
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Taking a bunch of stuff from 11 packages
* `builtins.attrNames gccNgPackages_11` now evaluates * Added missing inputs * Removed a bunch of clang-related things - clang-only packages: compiler-rt, libcxx, libcxxabi, openmp - useLLVM logic - stdenvs / cc-wrappers which are not applicable anymore * Removed LLVM-specific relics like the default callPackage bindings, clean up default callPackage scopes for libraries and tools * Add runtime libraries (may forgot some) to libraries set
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Oh no, I forgot to push my stuff! I'll merge. Actually comments won't be too bad. |
This was referenced Aug 11, 2021
Create patch so that thread model can be specified explicitly rather than being inferred from GCC.
There is a still a build failure, but I am going to just use Musl and ignore this for now.
Unfortunately, libstdcxx doesn't link, evidentally because inconsistent `-fPIC`.
| mkdir -p "$out/lib" "$dev/include" | ||
| ln -s "$out/lib/gcc/${stdenv.hostPlatform.config}/${version}"/* "$out/lib" | ||
| ln -s "$dev/lib/gcc/${stdenv.hostPlatform.config}/${version}/include"/* "$dev/include/" | ||
| ''; |
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I marked this as stale due to inactivity. → More info |
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Hi, It is a bummer that this sort of fell by the wayside. I just wanted to mention that enabling the goals of this PR is one of the major benefits sought by #209870. Specifically, if that PR merges, my next project will be to start moving the libraries that are bundled with gcc into separate packages -- like this PR, but one at a time, and incrementally rather than in a big rewrite. I would like to reuse as much of the work here as possible. |
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https://github.com/Ericson2314/nixpkgs/tree/gcc-ng-12 This was me trying to update this to a new GCC. |
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@amjoseph-nixpkgs #132343 (comment) it is a bummer, and I would love to pair with you on this to get it over the hill at some point. there was just some things I was banging my head against the wall debugging that I need another pair of eyes on. |
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This pull request has been mentioned on NixOS Discourse. There might be relevant details there: https://discourse.nixos.org/t/2023-10-31-nixpkgs-architecture-team-meeting-45/34846/1 |
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#### Summary
By default, when you type `make`, GCC will compile itself three
times. This PR inhibits that behavior by configuring GCC with
`--disable-bootstrap`, and reimplements the triple-rebuild using
Nix rather than `make`/`sh`.
#### Immediate Benefits
- Allow `gcc11` and `gcc12` on `aarch64` (without needing new
`bootstrapFiles`)
- Faster stdenv rebuilds: the third compilation of gcc
(i.e. stageCompare) is no longer a `drvInput` of the final stdenv.
This allows Nix to build stageCompare in parallel with the rest of
nixpkgs instead of in series.
- No more copying `libgcc_s` out of the bootstrap-files or other
derivations
- No more Frankenstein compiler: the final gcc and the libraries it
links against (mpfr, mpc, isl, glibc) are all built by the same
compiler (xgcc) instead of a mixture of the bootstrapFiles'
compiler and xgcc.
- No more [static lib{mpfr,mpc,gmp,isl}.a hack]
- Many other small `stdenv` hacks eliminated
- `gcc` and `clang` share the same codepath for more of `cc-wrapper`.
#### Future Benefits
- This should allow using a [foreign] `bootstrap-files` so long as
`hostPlatform.canExecute bootstrapFiles`.
- This should allow each of the libraries that ship with `gcc`
(lib{backtrace, atomic, cc1, decnumber, ffi, gomp, iberty,
offloadatomic, quadmath, sanitizer, ssp, stdc++-v3, vtv}) to be
built in separate (one-liner) derivations which `inherit src;`
from `gcc`, much like NixOS/nixpkgs#132343
#### Incorporates
- NixOS/nixpkgs#210004
- NixOS/nixpkgs#36948 (unreverted)
- NixOS/nixpkgs#210325
- NixOS/nixpkgs#210118
- NixOS/nixpkgs#210132
- NixOS/nixpkgs#210109
- NixOS/nixpkgs#213909
- NixOS/nixpkgs#216136
- NixOS/nixpkgs#216237
- NixOS/nixpkgs#210019
- NixOS/nixpkgs#216232
- NixOS/nixpkgs#216016
- NixOS/nixpkgs#217977
- NixOS/nixpkgs#217995
#### Closes
- Closes #108305
- Closes #108111
- Closes #201254
- Closes #208412
#### Credits
This project was made possible by three important insights, none of
which were mine:
1. @Ericson2314 was the first to advocate for this change, and
probably the first to appreciate its advantages. Nix-driven
(external) bootstrap is "cross by default".
2. @trofi has figured out a lot about how to get gcc to not mix up
the copy of `libstdc++` that it depends on with the copy that it
builds, by moving the `bootstrapFiles`' `libstdc++` into a
[versioned directory]. This allows a Nix-driven bootstrap of gcc
without the final gcc would still having references to the
`bootstrapFiles`.
3. Using the undocumented variable [`user-defined-trusted-dirs`]
when building glibc. When glibc `dlopen()`s `libgcc_s.so`, it
uses a completely different and totally special set of rules for
finding `libgcc_s.so`. This trick is the only way we can put
`libgcc_s.so` in its own separate outpath without creating
circular dependencies or dependencies on the bootstrapFiles. I
would never have guessed to use this (or that it existed!) if it
were not for a [comment in guix] which @Mic92 [mentioned].
My own role in this PR was basically: being available to go on a
coding binge at an opportune moment, so we wouldn't waste a
[crisis].
[aarch64-compare-ofborg]: https://github.com/NixOS/nixpkgs/pull/209870/checks?check_run_id=10662822938
[amd64-compare-ofborg]: https://github.com/NixOS/nixpkgs/pull/209870/checks?check_run_id=10662825857
[nonexistent sysroot]: NixOS/nixpkgs#210004
[versioned directory]: NixOS/nixpkgs#209054
[`user-defined-trusted-dirs`]: https://sourceware.org/legacy-ml/libc-help/2013-11/msg00026.html
[comment in guix]: https://github.com/guix-mirror/guix/blob/5e4ec8218142eee8e6e148e787381a5ef891c5b1/gnu/packages/gcc.scm#L253
[mentioned]: NixOS/nixpkgs#210112 (comment)
[crisis]: NixOS/nixpkgs#108305
[foreign]: NixOS/nixpkgs#170857 (comment)
[static lib{mpfr,mpc,gmp,isl}.a hack]: https://github.com/NixOS/nixpkgs/blob/2f1948af9c984ebb82dfd618e67dc949755823e2/pkgs/stdenv/linux/default.nix#L380
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Replaced by #414299 |
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Motivation for this change
Opening bare bones PR to collaborate on #132340
cc @Ericson2314 @sternenseemann
Things done
All cross compilation from
x86_64-unknown-linux-{gnu,musl}. Plug in the config in--crossSystem "{ config = \"$config\"; useGccNg = true; }"buildPackages.gccNgPackages.gcc-unwrappedaarch64-unknown-linux-gnuaarch64-unknown-linux-muslgccNgPackages.libgccaarch64-unknown-linux-gnuaarch64-unknown-linux-musllibcCrossaarch64-unknown-linux-gnuaarch64-unknown-linux-muslgccNgPackages.libatomicaarch64-unknown-linux-gnuaarch64-unknown-linux-muslgccNgPackages.libstdcxxaarch64-unknown-linux-gnuaarch64-unknown-linux-musl-fPICand-fno-PICsandboxinnix.confon non-NixOS linux)nix-shell -p nixpkgs-review --run "nixpkgs-review wip"./result/bin/)Upstream patches
Prefixed binaries in
-BdirsThread model specified per lib