Hi, I do not have any AMD systems to test upon, however, as far as I know nothing Intel SDE does depends on the manufacturer of the chip. By default, the STTNI emulation is enabled if the host hardware does not have STTNI support. In other words, I check the one CPUID bit for SSE4.2 (leaf 1, ecx[20]). If that is set to 1, then SDE does not enable the emulation. If it is set to 0, then the emulation occurs.
To force emulation on a chip that supports SSE4.2, you can use the knob "-sse42x". (You can see the numerous tool-specific knobs with "sde -thelp").
Your application or application compiler might be doing code selection based on other criteria and sending your program down another path. Or are you saying you see an illegal instruction error when you run under Intel SDE?