Call_stub is used when calling from C code into Java. It is supposed to implement the platform ABI.

Windows ABI requires the callee to save RBX, RBP, RDI, RSI, RSP, R12, R13, R14, R15, and XMM6-XMM15. We are saving all these, and save/restore xmm16-31 in addition to that. This is most likely unnecessary.

https://learn.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170#callercallee-saved-registers