CallTrace: Disassemble managed prestubs to find the real method address

[alexrp]

ruptura/src/memory/Diagnostics/CallFrame.cs

Lines 43 to 45 in 7016826

	// TODO: To do this correctly for managed methods, we have to disassemble the prestub and follow the jump.
	if (ManagedMethod == null && (byte*)IP - (byte*)Symbol.Address is var offset and not 0)
	_ = sb.Append(culture, $"+0x{offset:x}");

The issue is that the function pointer we get from RuntimeMethodHandle.GetFunctionPointer() points to the prestub for the method, but the instruction pointer we have (of course) points to the actual JIT'd method that was executed.

One way we might solve this is by disassembling the prestub and following the jump to the actual method. But we would need to know for sure that RuntimeMethodHandle.GetFunctionPointer() always returns a pointer to a prestub.

[alexrp]

Lots of useful information here: https://github.com/MonoMod/MonoMod.Common/blob/master/RuntimeDetour/Platforms/Runtime/DetourRuntimeNETPlatform.cs

Looks like this is not going to be fun.