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dotnet / dotnet-wasi-sdk

An SDK for building .NET projects as standalone WASI-compliant modules
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Is it possible to disable any optimisations and preserve stacktrace while building `.wasm`? #19

Open seclerp opened 1 year ago

seclerp commented 1 year ago

I'm currently looking into using .wasm as a standalone module to run on some custom WASI-compliant runtime. But it's impossible to debug any issues with calling native (.c) compiled functions because stacktrace with symbols is trimmed.

I also receive weird WASM exceptions like wasm trap: wasm 'unreachable' instruction executed which is almost impossible to diagnose.

seclerp commented 1 year ago

Answering my own question - it is possible, but very hard to do with the current hardcoded CLang args. See https://github.com/dotnet/dotnet-wasi-sdk/blob/main/src/Wasi.Sdk/build/Wasi.Sdk.targets#L217

Example:

  1. Stacktrace of the arbitrary unreachable exception with stripped symbols:

    0: error while executing at wasm backtrace:
       0: 0x4049c9 - <unknown>!<wasm function 7624>
       1: 0x3f5f3f - <unknown>!<wasm function 7301>
       2: 0x3f69c3 - <unknown>!<wasm function 7316>
       3: 0x3f6676 - <unknown>!<wasm function 7311>
       4: 0x3f6522 - <unknown>!<wasm function 7309>
       5: 0x3f676a - <unknown>!<wasm function 7313>
       6: 0x3f67f5 - <unknown>!<wasm function 7314>
       7: 0x29ff37 - <unknown>!<wasm function 4258>
       8: 0xf9fb9 - <unknown>!<wasm function 927>
       9: 0xe22e2 - <unknown>!<wasm function 712>
      10: 0xe2ef4 - <unknown>!<wasm function 720>
      11: 0x381b - <unknown>!<wasm function 48>
      12: 0x4180dc - <unknown>!<wasm function 7908>
1: wasm trap: wasm `unreachable` instruction executed

  2. The same stacktrace with .wasm compiled without -Wl,-s:

    0: error while executing at wasm backtrace:
       0: 0x4049c9 - <unknown>!abort
       1: 0x3f5f3f - <unknown>!monoeg_assert_abort
       2: 0x3f69c3 - <unknown>!monoeg_log_default_handler
       3: 0x3f6676 - <unknown>!monoeg_g_logstr
       4: 0x3f6522 - <unknown>!monoeg_g_logv_nofree
       5: 0x3f676a - <unknown>!monoeg_assertion_message
       6: 0x3f67f5 - <unknown>!mono_assertion_message
       7: 0x29ff37 - <unknown>!mono_alc_get_default
       8: 0xf9fb9 - <unknown>!mono_assembly_load
       9: 0xe22e2 - <unknown>!mono_wasm_assembly_load
      10: 0xe2ef4 - <unknown>!lookup_dotnet_method
      11: 0x381b - <unknown>!count_vowels
      12: 0x4180dc - <unknown>!count_vowels.command_export
   note: using the `WASMTIME_BACKTRACE_DETAILS=1` environment variable may show more debugging information
1: wasm trap: wasm `unreachable` instruction executed

  3. Using WASMTIME_BACKTRACE_DETAILS=1 (for Wasmtime runtime users):

    0: error while executing at wasm backtrace:
       0: 0x4049c9 - <unknown>!abort
       1: 0x3f5f3f - monoeg_assert_abort
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/eglib/goutput.c:57:3
       2: 0x3f69c3 - monoeg_log_default_handler
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/eglib/goutput.c:399:3
       3: 0x3f6676 - monoeg_g_logstr
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/eglib/goutput.c:151:2
       4: 0x3f6522 - monoeg_g_logv_nofree
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/eglib/goutput.c:166:2
       5: 0x3f676a - monoeg_assertion_message
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/eglib/goutput.c:207:22
       6: 0x3f67f5 - mono_assertion_message
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/eglib/goutput.c:226:2
       7: 0x29ff37 - mono_alc_get_default
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/metadata/assembly-load-context.c:81:2
       8: 0xf9fb9 - mono_assembly_load
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/mono/metadata/assembly.c:2853:46
       9: 0xe22e2 - mono_wasm_assembly_load
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/wasi/mono-wasi-driver/driver.c:542:22
      10: 0xe2ef4 - lookup_dotnet_method
                       at /home/runner/work/dotnet-wasi-sdk/dotnet-wasi-sdk/modules/runtime/src/mono/wasi/mono-wasi-driver/driver.c:816:30
      11: 0x381b - <unknown>!count_vowels
      12: 0x4180dc - <unknown>!count_vowels.command_export
1: wasm trap: wasm `unreachable` instruction executed
seclerp commented 1 year ago

I'll make a PR if it works.