On win64, xmm6-xmm15 are preserved registers, but the prologues and
epilogues of JITted code don't handle these. The issue occurs when
calling into the JIT code again via an internal handler
(like call_user_func). Therefore, we want to save/restore xmm registers
upon entering/leaving execute_ex. Since MSVC x64 does not support inline
assembly, we create an assembly wrapper around the real execute_ex
function.
The alternative is to always save/restore these xmm registers into the
fixed call frame, but this causes unnecessary overhead.
The same issue occurs for ARM64 platforms for floating point register
8 to 15. However, there we can use inline asm to fix this.
Closes GH-18352.
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