The issue we are working around is concerned with the lack of dead
code elimination in the aarch64-darwin LLVM codegen backend. Thus
the relevant condition is the target platform, not the host
platform as checked previously.
The condition used in the past to detect iOS was "is this
aarch64-darwin"? Since we have aarch64-darwin devices running macOS
nowadays which do allow large address space, let's use the more accurate
flag.
enableDwarf requires elfutils on the host, which doesn't support darwin.
Instead of hardcoded isDarwin/isWindows, switch to self-documenting
availableOn conditional for elfutils.
Fixes ghcHEAD cross-compilation when build = host = darwin,
target = linux.
Co-authored-by: sternenseemann <sternenseemann@systemli.org>
This is no substantial change, as we already assert that the
build->target and host->target LLVM are the same, but this brings the
terminology in the file in a more consistent order, since we use
build->target for CC/CXX and bintools already.
In fact we should be passing build->target to configure always,
host->target would come into play when updating GHC's settings file
after installing.
On aarch64-darwin we have additional wrappers for install_name_tool and
strip to deal with codesigning requirements (e. g. updating the
signature / checksum after changing a binary). These wrappers don't
exist on x86_64-darwin which is why the unwrapped versions were used
before, causing the kernel to kill (some) executables produced by GHC.
CC, CXX, LD, AR, …, LLC, OPT and CLANG will be invoked by GHC's build
system at build time in the build->target role. However, since we are
passing absolute paths, they will get saved in GHC's settings file and
later invoked at runtime, when they should be host->target. This means
that the build->target and host->target tools need to be the same for
our built GHC to work properly which is what we guard using these new
asserts.
Being able to drop these asserts would be a step towards cross-compiling
GHC (as opposed to building a GHC cross-compiler which still works).
* By taking clang from llvmPackages we make sure there is no version
mismatch between LLVM (where llc and opt come from) and clang (which
previously would be taken from stdenv on darwin for example).
* Only pass CLANG if useLLVM is true. Previously we also set this if
targetCC was clang. This would cause potentially confusing behavior if
llc and opt as well as clang are provided via PATH (and GHC is
compiled with useLLVM == false), because clang from PATH would be
ignored, but not llc and opt.
Since 4c75874560 it is possible to
introspect if ld.gold is contained in the used bintools, so we can also
check if it is available before deciding to use it as done in the other
GHC derivations in 0908812372.
These targets also have NCG support, but they are tested less (in fact
SPARC seems to be untested atm) and may have issues. In such cases being
able to fallback to -fllvm without rebuilding the compiler could be
useful. OTOH GHC will default to -fasm and the backends probably work
well enough in most cases.
GHC can actually accept absolute paths for its runtime tools (except for
touch) at configure time which are then saved in
`$out/lib/ghc-${version}/settings`. This allows us to drop the wrapper
entirely if we assume that a POSIX compliant touch is in PATH when we
run GHC later.
The touch problem can presumably be fixed by either patching the
configure file of GHC (although we need to take care not to change the
touch GHC uses during its compilation) or messing with the settings file
after installation.
The rationale for dropping the wrapper PATH entry completely is that
it's always possible to invoke GHC via its library which will bypass the
wrapper completely, leading to subtly different behavior.
Binary GHCs are not touched in this commit, but ideally they'll get a
similar treatment as well, so they are more robust, although we
generally don't need to use them as a library.
Note that GHC 8.8.4 doesn't care about install_name_tool or otool, so
the respective environment variables are not set.
This has two main benefits:
* GHC will work reliably outside of stdenv, even when using -fllvm since
everything it'll call at runtime will be provided in PATH via the
wrapper scripts.
* LLVM will no longer leak into haskell packages' configure
scripts. This was an issue with llvm-hs which fails to build if the
LLVM version of the compiler since the propagatedBuildInputs of GHC
take precedence over the nativeBuildInputs added in the derivation.
This brings the binary GHCs on parity with the source built ones in
terms of the wrapper. The upshot of this is that compiling something
using the binary GHCs no longer depends on PATH being populated with
the tools included in stdenv at all. We can even test this by running
the installCheck with an empty environment (via `env -i`).
Copy the approach from the normal GHC derivations for adding an
`export PATH` into the scripts in `$out/bin` and use it to put the
specific LLVM version of the binary GHC into its PATH. This will
prevent the LLVM version of the GHC we are building later to take
precedence over the LLVM version this GHC needs.
Since we inherit the platform list from the bootstrap GHC, we get
differing lists depending on which platform we evaluate the platform
list on (depending on whether 8.10.2 or 8.6.5 is used). This leads to
Hydra thinking aarch64-linux is not supported as it evaluates on
x86_64-linux usually.
Since LLVM itself doesn't depend on target at all, this doesn't change
anything *in effect* (i. e. rebuild count should be zero), but it is
more clear about the intention and what LLVM is used for here (i. e. in
depsBuildTarget).
This means we only have to update the llvmPackages attribute in one
place now and should prevent situations like with 8.6.5 where different
versions would be used in the package set compared to the compiler
build.
Drop comments in the configuration-ghc-X.Y.x.nix files as well, since
LLVM version isn't tied to the compiler minor version at
all (e. g. 8.10.2 and 8.10.7 have different support ranges).
Reverse bootstrapping is not supported by GHC upstream. In the case of
8.8.4 it just happens to work using 8.10.2, with later versions,
specifically 8.10.7 there seems to be some digressions in the generated /
used C code which cause 8.8.4 to fail to compile [1].
Thus we revert to using 8.10.2 for aarch64 and Musl which means: Still
no integer-simple and musl at the same time (however all other GHCs have
it, so it's probably not a problem) and no aarch64-darwin (GHC 8.8.4
can't target that architecture anyways). In short, the situation stays
the same.
[1]: https://github.com/NixOS/nixpkgs/pull/138523#issuecomment-927339953
When debugging musl builds, I often have to sift through thousands of lines
of `nix-store -q --tree` or `nix-store -qR` output.
Until now, `pkgsMusl` and normal `pkgs` GHCs looked exactly the same in
there, making that task tough.
Same for `integer-simple`, which makes debugging `gmp` issues easier.
This commit introduces a suffix to tell them apart easily.
Note that this is different from `targetPrefix` which is for
cross-compilation, which `pkgsMusl` does not do.
For GHC HEAD, integer-simple no longer exists, instead we now have a
“bignum backend”, so we just call the integer-simple successor
native-bignum.
Co-Authored-By: sternenseemann <sternenseemann@systemli.org>
GHC HQ switched the musl bindists from gmp to `integer-simple`
with GHC >= 8.10.6, but this was not reflected in the nixpkgs update:
* commit 6f1242469a: ghc: 8.10.5-binary -> 8.10.7-binary
From PR #135453
See also #130441.
