Well, I accidentally voted yes, when my answer is that I don't know.
Inspectre says YES, YES, and GOOD for both of my home PCs. but I don't know what version of Spectre it reports on.
That fix, called Retpoline, addresses Variant 2 of the two Spectre CPU attacks called 'branch target injection'. Variant 2 is considered by Microsoft and Google to be the trickiest speculative execution vulnerability to fix as it's the only one that does cause a significant hit on CPU performance.
The other way of fixing Variant 2 is via a blend of OS/kernel fixes and silicon microcode from Intel and AMD, but Google contends its software-based Retpoline answer is superior and should be adopted universally.
Mitigations for speculation-based, side-channel security issues fall into two categories: directly manipulating speculation hardware, or indirectly controlling
speculation behavior. Direct manipulation of the hardware is generally per formed by microcode updates or manipulation of hardware registers. Indirect control is
accomplished via software constructs that limit or constrain speculation. Retpoline is a hybrid approach since it requires updated microcode to make the speculation
hardware behavior more predictable on some processor models. However, retpoline is primarily a software construct that leverages specific knowledge of the underlying
hardware to mitigate branch target injection (Spectre variant 2).
Mitigation with retpoline requires that all code in a program (or OS kernel) is compiled with a retpoline-enabled compiler in order to make sure vulnerable
indirect branches are replaced with the retpoline sequence. In practice, this means that retpoline can only be applied in environments where recompilation and redeployment of updated binaries is possible. This includes instances where full source code is available, or where instructions are generated by a JIT compiler.
However, retpoline is not a practical mitigation for environments where full recompilation itself is not practical. Other mitigations may be appropriate in those environments.