llvm@7: add support for Apple Silicon #65628

hjelmn · 2020-11-25T00:34:58Z

This commit updates the llvm@7 formula to allow it to be built on Apple
Silicon Macs. This package is needed to build ghc@8.8 on this platform.

The change includes backporting several patches from llvm master which
fix compilation and building on macOS with arm64.

Signed-off-by: Nathan Hjelm hjelmn@google.com

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This commit updates the llvm@7 formula to allow it to be built on Apple Silicon Macs. This package is needed to build ghc@8.8 on this platform. The change includes backporting several patches from llvm master which fix compilation and building on macOS with arm64. Signed-off-by: Nathan Hjelm <hjelmn@google.com>

SMillerDev · 2020-11-25T08:57:24Z

Formula/llvm@7.rb

+    patch do
+      url "https://gist.githubusercontent.com/hjelmn/9fa1a7742acad71f404544a03bda414a/raw/b56a25f7208023d9724f671dfd7a80cbdac2a612/cfe-7.1.0-darwin-arm64.patch"
+      sha256 "eb6be925cdab150f5d01d51fa6bd6a4fe1dbf481794b83976ff877524192d1c1"
+    end


These are gonna need to be submitted upstream to be considered for inclusion in homebrew

LLVM 7 isn't updated anymore upstream, this is basically a legacy package.

If it's abandoned it should be deprecated and we still shouldn't use random patches that aren't submitted upstream

These changes are all upstream. Just backported to llvm7 because it is no longer maintained. The only reason I request this is llvm7 is needed to build the ghc llvm backend. There is no native backend for ARM64 yet.

I suppose the alternative is I make a keg, correct?

fxcoudert · 2020-11-25T14:16:14Z

In Homebrew, the only thing that depends on llvm@7 is nvc, which has very low analytics and is not likely to get recent LLVM support anytime soon (nickg/nvc@c3d1ae5). So we don't have a need for an ARM backport, really.

This package is needed to build ghc@8.8 on this platform

Can you explain this? None of our ghc formulas need LLVM to build, they all build fine with system compiler.

hjelmn · 2020-11-25T14:32:56Z

Building ghc 8.8 (I need to try 8.10 but it likely has the same issue since there still is no native code generator) and it errors out with a newer llvm. Complains that the llvm is too new and says to use 7. From what I can tell this doesn't affect x86_64 because that uses a different backend. I can run some more attempts but the turn around is slow since ghc needs to be built twice. Once cross compiled and once native. I may just build a call with these until upstream ghc natively supports arm64.

hjelmn · 2020-11-26T06:31:15Z

This will take a couple of days but I will try to build with the latest llvm in homebrew. I will report back if there is an error (I saw one before with llvm 11). I don't really care about llvm@7 except as a dependency to ghc@8.8.

hjelmn · 2020-11-28T04:22:23Z

ghc 8.10.2 builds with llvm 11 (the formula in homebrew already works on Apple Silicon). ghc 8.10.2 requires patching to deal with issues with the aarch64 vs arm64 architecture naming but otherwise it seems to work fine. 8.8.4 mostly works but has some issues (after the same set of patches) with the linker code. these were fixed somewhere between 8.8.4 and 8.10.2.

carlocab · 2020-11-28T04:33:08Z

Does the stable version of llvm 11 work? With libomp?

fxcoudert · 2020-11-28T10:39:09Z

Does the stable version of llvm 11 work? With libomp?

Released llvm 11.0.0 builds and works on ARM Big Sur. We carry a small patch for libomp in the formula.

hjelmn · 2020-11-30T15:26:23Z

Both my ghc 8.8 and 8.10 formula changes fail because of the shim compiler adding linker flags when cross compiling:

[291 of 291] Compiling Main             ( utils/ghc-cabal/Main.hs, bootstrapping/Main.o )
Linking utils/ghc-cabal/dist/build/tmp/ghc-cabal ...
ld: in '/opt/homebrew/opt/llvm/lib/libunwind.dylib', building for macOS-x86_64 but attempting to link with file built for macOS-arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
`clang' failed in phase `Linker'. (Exit code: 1)
make[1]: *** [utils/ghc-cabal/dist/build/tmp/ghc-cabal] Error 1
make: *** [all] Error 2

I tried to bypass these wrappers by prepending /usr/bin to the path but they still get used. If there isn't a way to bypass the shim compilers then I will have to modify them to work when cross compiling in this way.

carlocab · 2020-11-30T15:29:42Z

I've seen standard overrides for the shims by replacing/setting environment variables, though I imagine you've already tried that...

Also, --env=std flag to brew install? (I haven't used this, so maybe I'm confused about how this works.)

hjelmn · 2020-11-30T15:32:49Z

Looks like --env=std does indeed block the wrappers from getting in the way.

With --env=std --interactive:

bash-3.2$ type -p clang
/opt/homebrew/opt/llvm/bin/clang

Without:

bash-3.2$ type -p clang
/opt/homebrew/Library/Homebrew/shims/mac/super/clang

hjelmn · 2020-11-30T15:48:17Z

Dropping llvm from the dependency list helps. Will see how far that gets since ghc 8.8.4 would always fail it it couldn't locate llc (it also complained about opt missing). 8.10 may be more forgiving if it isn't a full llvm install. If this works I will get the ghc.rb change up in a PR today.

hjelmn · 2020-11-30T17:34:56Z

Looks like it will work with the system compiler. Forgot the make clean step so failed on the full build. Added the missing step and attempting again. Getting close to a working ghc formula.

hjelmn · 2020-11-30T20:34:01Z

🍺 /opt/homebrew/Cellar/ghc/8.10.2_2: 6,889 files, 1.9GB, built in 157 minutes 40 seconds

$ file /opt/homebrew/Cellar/ghc/8.10.2_2/lib/ghc-8.10.2/bin/ghc
/opt/homebrew/Cellar/ghc/8.10.2_2/lib/ghc-8.10.2/bin/ghc: Mach-O 64-bit executable arm64

fxcoudert · 2020-11-30T20:57:58Z

Great!
Can this be closed?

hjelmn · 2020-11-30T21:26:44Z

Yeah. ghc 8.8 is not worth fixing at this time.

BrewTestBot added the legacy Relates to a versioned @ formula label Nov 25, 2020

hjelmn mentioned this pull request Nov 25, 2020

ghc: apply arm64 compatibility patch to static gmp #57892

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hjelmn closed this Nov 30, 2020

carlocab mentioned this pull request Dec 1, 2020

llvm: add upstream patch that fixes build for ARM. #65973

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llvm@7: add support for Apple Silicon #65628

llvm@7: add support for Apple Silicon #65628

hjelmn commented Nov 25, 2020

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llvm@7: add support for Apple Silicon #65628

llvm@7: add support for Apple Silicon #65628

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