hoodmane wrote: The goal is as an alternative to `EMULATE_FUNCTION_POINTER_CASTS` for projects like Python and GLib that do dispatch with sometimes-incorrect function pointers. In particular, rather than having to `call_indirect` a function pointer and find out whether or not we trap, I want a way to query the function pointer ahead of time for whether the call will succeed.
In the ideal case the solution should: 1. work on wasm32-unknown-unknown so it's portable between Emscripten and wasi 2. not require dropping down to assembly or JS My idea is to add a clang builtin `__builtin_wasm_test_function_pointer_signature` so I can replace this whole file: https://github.com/python/cpython/blob/main/Python/emscripten_trampoline.c with: ```C typedef PyObject* (*zero_arg)(void); typedef PyObject* (*one_arg)(PyObject*); typedef PyObject* (*two_arg)(PyObject*, PyObject*); typedef PyObject* (*three_arg)(PyObject*, PyObject*, PyObject*); PyObject* _PyEM_TrampolineCall(PyCFunctionWithKeywords func, PyObject* self, PyObject* args, PyObject* kw) { if (__builtin_wasm_test_function_pointer_signature((zero_arg)func)) return ((zero_arg)func)(); if (__builtin_wasm_test_function_pointer_signature((one_arg)func)) return ((one_arg)func)(self); if (__builtin_wasm_test_function_pointer_signature((two_arg)func)) return ((two_arg)func)(self, args); if (__builtin_wasm_test_function_pointer_signature((three_arg)func)) return ((three_arg)func)(self, args, kw); PyErr_SetString(PyExc_SystemError, "Handler has unexpected signature"); return NULL; } ``` https://github.com/llvm/llvm-project/pull/147076 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
