make cross build from arm64 work..
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Authored by jmg on Feb 24 2023, 6:47 PM.

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dim
emaste
imp

Commits

rG9c2dbbe2b55a: make cross build from arm64 work..
rGeb81dd8404e5: make cross build from arm64 work..

Summary

If you try to build amd64 from an an arm64 machine, you'll get:
ld: error: undefined hidden symbol: blake3_hash_many_neon

and that is because when _ARCH != arm64, the neon file isn't
compiled/linked, but when building the cross tool, it detects
it's on arm64 and automatically enables it.

This copies want is done for the AVX and other x86 specific
optimizations.

With this change, I was successful in building (and booting) an
amd64 world from an arm64 box...

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rG FreeBSD src repository

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Event Timeline

jmg created this revision.Feb 24 2023, 6:47 PM

Herald added subscribers: imp, emaste. · View Herald TranscriptFeb 24 2023, 6:47 PM

jmg requested review of this revision.Feb 24 2023, 6:47 PM

Harbormaster completed remote builds in B49995: Diff 117887.Feb 24 2023, 6:47 PM

emaste added inline comments.Feb 24 2023, 7:05 PM

lib/clang/libllvm/Makefile
35	mild curiosity, I wonder why they ended up with other than `-DBLAKE3_NO_NEON`

LGTM. Please MFC.

lib/clang/libllvm/Makefile
35	This was brought in separately in https://github.com/llvm/llvm-project/commit/34362f96d2c0b: To accomodate macOS universal configuration include the assembly files and `blake3_neon.c` without a CMake check but instead guard their source with architecture "#ifdef" checks. In LLVM there is an eclectic mix of the styles: `#define FOO` or `#undef FOO`, then check with `#ifdef FOO` or `#ifndef FOO` `#define FOO 0` or `#define FOO 1`, then check with `#if FOO` or `#if !FOO` I'd rather just use one style, but currently it's hit and miss... :)

This revision is now accepted and ready to land.Feb 24 2023, 7:17 PM

emaste accepted this revision.Feb 24 2023, 9:14 PM

Seems to check out.

contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_dispatch.c:#if BLAKE3_USE_NEON == 1
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_dispatch.c:#if BLAKE3_USE_NEON == 1
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h:#if !defined(BLAKE3_USE_NEON) 
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h:  // If BLAKE3_USE_NEON not manually set, autodetect based on AArch64ness
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h:    #define BLAKE3_USE_NEON 1
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h:    #define BLAKE3_USE_NEON 0
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h:#elif BLAKE3_USE_NEON == 1
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h:#if BLAKE3_USE_NEON == 1
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_neon.c:#if BLAKE3_USE_NEON
contrib/llvm-project/llvm/lib/Support/BLAKE3/blake3_neon.c:#endif // BLAKE3_USE_NEON

and

#if !defined(BLAKE3_USE_NEON)
  // If BLAKE3_USE_NEON not manually set, autodetect based on AArch64ness                                                                                                                                                                     
  #if defined(IS_AARCH64)
    #define BLAKE3_USE_NEON 1
  #else
    #define BLAKE3_USE_NEON 0
  #endif
#endif

so yea, we really need it and there's no other clever way around it.

Closed by commit rGeb81dd8404e5: make cross build from arm64 work.. (authored by jmg). · Explain WhyFeb 24 2023, 10:26 PM

This revision was automatically updated to reflect the committed changes.

jmg added a commit: rGeb81dd8404e5: make cross build from arm64 work...

dim added a commit: rG9c2dbbe2b55a: make cross build from arm64 work...Jan 7 2024, 11:10 PM