NDS32 missing inline function call instructions

[CUB3D]

As discussed elsewhere (#6627), NDS32 supports "inline function calls". This is implemented using the IFCALL, IFCALL9, IFRET and IFRET16 instructions. Currently Ghidra doesn't support these which leads to incorrect function disassembly.

Here's an example binary with the missing instructions:

Source code

int main() {
    asm("ifcall9 0x10");
    asm("ifcall 0x10");
    asm("ifret");
    asm("ifret16");
    return 0;
}    

Compile with ./nds32le-elf-mculib-v3s/bin/nds32le-elf-gcc -c test.c
Binary toolchain available here

nds32_ifcall.zip

[GhidorahRex]

These instructions should get spec'd out, but semantics will be trickier. As @shuffle2 highlighted, even with getting the disassembly and initial sleigh pcode written, there still might be some lingering issues.

If someone was interested in submitting a PR to add these instructions to our NDS32 module, I would definitely be willing to review it and prioritize it for inclusion. I think these instructions are particularly important.