emscripten_memcpy_big when bulk-memory enabled

[miwelc]

I've seen in the emitted JS code that emscripten_memcpy_big is being defined even if -mbulk-memory is enabled.
Is this the expected behavior?

[RReverser]

Running into this as well. Not critical, but looks like this issue might've slipped under the radar?

[sbc100]

I don't see anything in the code that would stop emscripten_memcpy_big from being used. What makes you think this is not expected behaviour? Are you expecting an explict call to the memory.copy builtin here:

emscripten/system/lib/libc/emscripten_memcpy.c

Lines 37 to 42 in 168dafb

	#ifndef EMSCRIPTEN_STANDALONE_WASM
	if (n >= 512) {
	emscripten_memcpy_big(dest, src, n);
	return dest;
	}
	#endif

One problem with doing that is that we probably wouldn't want to build a specific / separate version of libc when bulk-memory is enabled.

[RReverser]

What makes you think this is not expected behaviour?

Nothing except that it feels like it should be, sort of like -fwasm-exceptions reduces overhead by replacing exception imports from JS with native Wasm functionality.

Are you expecting an explict call to the memory.copy builtin here:

Yeah.

[RReverser]

Looks like this was implemented in #19128.