c-api: Enable debugger DWARF export for guest code #9915
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In order to allow source level debugging of hosted webassembly code in C-based embeddings, we must enable the debug-builtins cargo feature when building the C api.
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Previously we were testing and confirming only that the options can be set using the API, not that they actually have any effect. In order to (simply) confirm that enabling debug information actually created some debug information, we can somewhat hackily inspect the generated GDB JIT descriptor to see that it's populated.
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alexcrichton
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Dec 30, 2024
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In order to allow source level debugging of hosted webassembly code in C-based embeddings, we must enable the debug-builtins cargo feature when building the C api. This allows for embeddings of wasmtime in non-rust environments to benefit from the integration with gdb/lldb's JIT debug interface.
Fixes #9909
Tests: I have tested this manually per the notes in the linked issue, and have single-stepped through the code to confirm it is behaving as I expect (I basically did a side-by side step through with an equivalent rust program linked with the default settings and
wasmtimecargo dependency).For automated tests, I have a simple strategy: I can validate that the GDB structures are actually set up in the fib-debug/main.c. It's a little hacky so I've added as a second commit. The strategy is to validate the actual
__jit_debug_descriptorthat's created is non-NULL after instantiation. As these examples are used by other people, I have gated the code with a compile definition that's only set during the tests.I have confirmed this test fails without my patch and passes with it.