Arm build leg failing in runtime for 8.0 P4

[mthalman]

      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cpp:26:
      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/UnwindCursor.hpp:44:
      /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/DwarfInstructions.hpp:234:33: error: unknown architectural extension: memtag
                                     ".arch_extension memtag\n"
                                      ^
      <inline asm>:2:17: note: instantiated into assembly here
      .arch_extension memtag
                      ^
      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cpp:26:
      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/UnwindCursor.hpp:44:
      /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/DwarfInstructions.hpp:235:33: error: instruction requires: mte
                                     "stg %[Ptr], [%[Ptr]]\n"
                                      ^
      <inline asm>:3:1: note: instantiated into assembly here
      stg x8, [x8]
      ^
      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cpp:26:
      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/UnwindCursor.hpp:44:
      /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/DwarfInstructions.hpp:234:33: error: unknown architectural extension: memtag
                                     ".arch_extension memtag\n"
                                      ^
      <inline asm>:2:17: note: instantiated into assembly here
      .arch_extension memtag
                      ^
      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cpp:26:
      In file included from /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/UnwindCursor.hpp:44:
      /vmr/src/runtime/artifacts/source-build/self/src/src/native/external/llvm-libunwind/src/DwarfInstructions.hpp:235:33: error: instruction requires: mte
                                     "stg %[Ptr], [%[Ptr]]\n"
                                      ^
      <inline asm>:3:1: note: instantiated into assembly here
      stg x8, [x8]
      ^
      4 errors generated.
make[2]: *** [nativeaot/Runtime/Full/CMakeFiles/Runtime.WorkstationGC.dir/build.make:849: nativeaot/Runtime/Full/CMakeFiles/Runtime.WorkstationGC.dir/__/unix/UnwindHelpers.cpp.o] Error 1
      make[2]: *** Waiting for unfinished jobs....
      make[1]: *** [CMakeFiles/Makefile2:3179: nativeaot/Runtime/Full/CMakeFiles/Runtime.WorkstationGC.dir/all] Error 2
      make: *** [Makefile:149: all] Error 2
      /vmr/src/runtime/artifacts/source-build/self/src/src/coreclr
##[error]Failed to build "CoreCLR component".

Build link (internal)

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[mthalman]

Adding @jkotas @trylek for help.

[jkotas]

@VSadov Is this the same issue you have into in dotnet/runtime#85283 (comment)?

[jkotas]

cc @am11 Looks like this was introduce by https://github.com/dotnet/runtime/pull/85179/files#diff-a9983f617332e1171626041a0e71ac60f707fa12996ed0e801326e489603319dR234

[mthalman]

FYI: We'll need to have this addressed for the Preview 4 release since it's blocking source-build.

[VSadov]

@jkotas - yes it looks like the same issue.

[VSadov]

It seems like the following fixes it. But we must be careful if we need to compile this with GCC.

   -                            ".arch_extension memtag\n"
   +                            ".arch_extension mte\n"

[VSadov]

Perhaps do memtag for GCC and mte with clang, to be safe?

I do not know what exactly causes the break to appear. My change made it to appear, but it was completely unrelated.

[am11]

FYI: We'll need to have this addressed for the Preview 4 release since it's blocking source-build.

We shouldn't be using gcc toolchain in official legs as it is a community supported platform. Runtime builds are tested with clang, and that's what is recommended for end-users: https://learn.microsoft.com/en-us/dotnet/core/deploying/native-aot/#prerequisites.

Things should work with gcc (nice to have) but it shouldn't block any official build.

[jkotas]

This is clang build break. Here is a small test:

root@b18ef9da89c7:/# cat test.c
int main()
{
          void* p = 0;
          __asm__ __volatile__(".arch armv8.5-a\n"
                               ".arch_extension memtag\n"
                               "stg %[Ptr], [%[Ptr]]\n"
                               :
                               : [Ptr] "r"(p)
                               : "memory");
}
root@b18ef9da89c7:/# clang test.c
test.c:5:33: error: unknown architectural extension: memtag
                               ".arch_extension memtag\n"
                                ^
<inline asm>:2:17: note: instantiated into assembly here
.arch_extension memtag
                ^
test.c:6:33: error: instruction requires: mte
                               "stg %[Ptr], [%[Ptr]]\n"
                                ^
<inline asm>:3:1: note: instantiated into assembly here
stg x8, [x8]
^
2 errors generated.
root@b18ef9da89c7:/#

The build container with the failure is mcr.microsoft.com/dotnet-buildtools/prereqs:debian-11-arm64v8

[am11]

It requires a new(er) assembler: apt install -y clang-13 then calng-13 test.c succeeds. ref: https://reviews.llvm.org/D103726?id=350009#2862258