Build failing on Cygwin: .hidden directive in BLAKE3 assembly

[SamB]

I'm using Cygwin, with this assembler:

$ cygcheck -f /bin/as
binutils-2.37-2

I'm trying to build clangd from llvm-project (commit llvmorg-15-init-6331-gd345fe7c221f -- that's a refspec from git describe).

I configured using this command:

cmake -S llvm -B build -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" -GNinja

Building twice (because you don't need to see the successful steps), I get this output:

$ ninja -C build -k0
ninja: Entering directory `build'
[1/4502] Building ASM object lib/Suppo...lake3.dir/blake3_sse41_x86-64_unix.S.o
FAILED: lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse41_x86-64_unix.S.o
/usr/bin/cc -DGTEST_HAS_RTTI=0 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/Support/BLAKE3 -I/home/naest/llvm-project/llvm/lib/Support/BLAKE3 -Iinclude -I/home/naest/llvm-project/llvm/include -O3 -DNDEBUG -MD -MT lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse41_x86-64_unix.S.o -MF lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse41_x86-64_unix.S.o.d -o lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse41_x86-64_unix.S.o -c /home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S: Assembler messages:
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S:22: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S:23: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S:24: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S:25: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S:26: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S:27: Error: unknown pseudo-op: `.hidden'
[2/4502] Building ASM object lib/Suppo...Blake3.dir/blake3_sse2_x86-64_unix.S.o
FAILED: lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse2_x86-64_unix.S.o
/usr/bin/cc -DGTEST_HAS_RTTI=0 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/Support/BLAKE3 -I/home/naest/llvm-project/llvm/lib/Support/BLAKE3 -Iinclude -I/home/naest/llvm-project/llvm/include -O3 -DNDEBUG -MD -MT lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse2_x86-64_unix.S.o -MF lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse2_x86-64_unix.S.o.d -o lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_sse2_x86-64_unix.S.o -c /home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S: Assembler messages:
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S:22: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S:23: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S:24: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S:25: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S:26: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S:27: Error: unknown pseudo-op: `.hidden'
[3/4502] Building ASM object lib/Suppo...Blake3.dir/blake3_avx2_x86-64_unix.S.o
FAILED: lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx2_x86-64_unix.S.o
/usr/bin/cc -DGTEST_HAS_RTTI=0 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/Support/BLAKE3 -I/home/naest/llvm-project/llvm/lib/Support/BLAKE3 -Iinclude -I/home/naest/llvm-project/llvm/include -O3 -DNDEBUG -MD -MT lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx2_x86-64_unix.S.o -MF lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx2_x86-64_unix.S.o.d -o lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx2_x86-64_unix.S.o -c /home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S: Assembler messages:
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S:22: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S:23: Error: unknown pseudo-op: `.hidden'
[4/4502] Building ASM object lib/Suppo...ake3.dir/blake3_avx512_x86-64_unix.S.o
FAILED: lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx512_x86-64_unix.S.o
/usr/bin/cc -DGTEST_HAS_RTTI=0 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/Support/BLAKE3 -I/home/naest/llvm-project/llvm/lib/Support/BLAKE3 -Iinclude -I/home/naest/llvm-project/llvm/include -O3 -DNDEBUG -mavx512vl -MD -MT lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx512_x86-64_unix.S.o -MF lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx512_x86-64_unix.S.o.d -o lib/Support/BLAKE3/CMakeFiles/LLVMSupportBlake3.dir/blake3_avx512_x86-64_unix.S.o -c /home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S: Assembler messages:
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S:22: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S:23: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S:24: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S:25: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S:26: Error: unknown pseudo-op: `.hidden'
/home/naest/llvm-project/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S:27: Error: unknown pseudo-op: `.hidden'
ninja: build stopped: cannot make progress due to previous errors.

I tried fixing the relevant CMakeLists.txt to use the _windows_gnu.S files for Cygwin, but curiously these also contain .hidden (ELF symbol visibility) directives, despite the fact that PE-COFF doesn't use ELF symbol visibility.

[mstorsjo]

I noticed this when building for mingw too - I posted https://reviews.llvm.org/D122893 which should get rid of the .hidden directives in the windows-gnu assembly files. Then I presume it'd be needed to add a change like this:

diff --git a/llvm/lib/Support/BLAKE3/CMakeLists.txt b/llvm/lib/Support/BLAKE3/CMakeLists.txt
index d07de305ff86..b3af312b2155 100644
--- a/llvm/lib/Support/BLAKE3/CMakeLists.txt
+++ b/llvm/lib/Support/BLAKE3/CMakeLists.txt
@@ -59,7 +59,7 @@ if (IS_X64 AND CAN_USE_ASSEMBLER)
       blake3_avx2_x86-64_windows_msvc.asm
       blake3_avx512_x86-64_windows_msvc.asm
     )
-  elseif(WIN32)
+  elseif(WIN32 OR CYGWIN)
     list(APPEND LLVM_BLAKE3_FILES
       blake3_sse2_x86-64_windows_gnu.S
       blake3_sse41_x86-64_windows_gnu.S

to use those assembly files for Cygwin too.

If you get it built that way, it'd be good to build unittests/Support/SupportTests.exe and run it with the --gtest_filter=BLAKE3* parameter to know that the blake3 implementation works.

[SamB]

Yeah, thanks to your change, that one-line change is the only thing left in my git diff output :-D.

And I'm quite happy to learn that there's no difference here between Cygwin as and mingw as; it's a lot easier to believe that someone might forget to test a change before committing than to believe that Cygwin would somehow be missing as syntax that mingw has (although still kind of unexpected).

The BLAKE3 tests both pass here, too.

[mstorsjo]

Yeah, thanks to your change, that one-line change is the only thing left in my git diff output :-D.

And I'm quite happy to learn that there's no difference here between Cygwin as and mingw as; it's a lot easier to believe that someone might forget to test a change before committing than to believe that Cygwin would somehow be missing as syntax that mingw has (although still kind of unexpected).

The BLAKE3 tests both pass here, too.

Ok, great, thanks for confirming! I posted https://reviews.llvm.org/D123187 with the remaining fix then.

[mstorsjo]

By the way - do you use Clang to build Cygwin-native code too, or do you only use it for cross compiling for other targets? I'm wondering, because the Cygwin target within LLVM/Clang isn't very much maintained, and I'm curious about its state (i.e. does it work satisfactory for the subset of code you regularly compile and no maintainance is needed - or is it broken?).

[SamB]

@mstorsjo I haven't actually used it to build anything yet, I just wanted a clangd that speaks the same path syntax as Cygwin emacs ... but it turns out that clangd can't quite find the headers yet, since the patch https://cygwin.com/git-cygwin-packages?p=git/cygwin-packages/clang.git;a=blob_plain;f=7.0.1-cygwin-driver.patch;hb=e1fccf772aa5add40bba9050abeea188c62acbdd hasn't been upstreamed.