- Compatible with Emscripten 1.38.46-upstream or later upstream.
- Refactors the Emscripten target spec to share code with other wasm
targets.
- Replaces the old incorrect wasm32 C call ABI with the correct one,
preserving the old one as wasm32_bindgen_compat for wasm-bindgen
compatibility.
- Updates the varargs ABI used by Emscripten and deletes the old one.
- Removes the obsolete wasm32-experimental-emscripten target.
- Uses EMCC_CFLAGS on CI to avoid the timeout problems with #63649.
On architectures such as powerpc64 that use extend_integer_width_to in
their C ABI processing, integer parameters shorter than the native
register width will be annotated with the ArgAttribute::SExt or
ArgAttribute::ZExt attribute, and that attribute will be included in the
generated LLVM IR.
In this test, all relevant parameters are `i32`, which will get the
`signext` annotation on the relevant 64-bit architectures. Match both
the annotated and non-annotated case, but enforce that the annotation is
applied consistently.
