assembler: Optimize mov rAX,[int32-offset] (64-bit mode)

[wtfsck]

It's currently always using mov rAX,[moffs] but if it fits in an i32, it's shorter to use mov rAX,[m] with a modrm byte.

The generated mov() methods would need to be updated. This is what the generated C# code looks like:

			if (dst.Value == Register.RAX && Bitness == 64 && src.IsDisplacementOnly) {
				code = Code.Mov_RAX_moffs64;

An extra check would need to be added to the first line to check if the displacement fits in an Int32, and if so, don't use mov rax,[moffs].

iced/src/csharp/Intel/Generator/Assembler/CSharp/CSharpAssemblerSyntaxGenerator.cs

Lines 938 to 941 in a49d0e6

	OpCodeSelectorKind.MemOffs64_RAX => $"{otherArgName}.Value == {GetRegisterString(nameof(Register.RAX))} && Bitness == 64 && {argName}.IsDisplacementOnly",
	OpCodeSelectorKind.MemOffs64_EAX => $"{otherArgName}.Value == {GetRegisterString(nameof(Register.EAX))} && Bitness == 64 && {argName}.IsDisplacementOnly",
	OpCodeSelectorKind.MemOffs64_AX => $"{otherArgName}.Value == {GetRegisterString(nameof(Register.AX))} && Bitness == 64 && {argName}.IsDisplacementOnly",
	OpCodeSelectorKind.MemOffs64_AL => $"{otherArgName}.Value == {GetRegisterString(nameof(Register.AL))} && Bitness == 64 && {argName}.IsDisplacementOnly",

iced/src/csharp/Intel/Generator/Assembler/Rust/RustAssemblerSyntaxGenerator.cs

Lines 887 to 890 in a49d0e6

	OpCodeSelectorKind.MemOffs64_RAX => $"{otherArgName}.register() == {GetRegisterString(nameof(Register.RAX))} && self.bitness() == 64 && {argName}.is_displacement_only()",
	OpCodeSelectorKind.MemOffs64_EAX => $"{otherArgName}.register() == {GetRegisterString(nameof(Register.EAX))} && self.bitness() == 64 && {argName}.is_displacement_only()",
	OpCodeSelectorKind.MemOffs64_AX => $"{otherArgName}.register() == {GetRegisterString(nameof(Register.AX))} && self.bitness() == 64 && {argName}.is_displacement_only()",
	OpCodeSelectorKind.MemOffs64_AL => $"{otherArgName}.register() == {GetRegisterString(nameof(Register.AL))} && self.bitness() == 64 && {argName}.is_displacement_only()",