Microsoft's x86-64 calling convention ABI requires registers XMM6-15 to be preserved by the callee: https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=vs-2017#calling-convention-defaults Implement a _pop_reg() analog to _push_reg(), so we can specialize the XMM treatment. Pass the RegNum all the way down to the specialized class, because we don't know which registers should be 128-bit at the call site. Bug chromium:931926 Bug swiftshader:22 Change-Id: I57637c852f0f3bb9a374d61a16a7aaa434ac908d Reviewed-on: https://swiftshader-review.googlesource.com/c/25468Reviewed-by: Nicolas Capens <nicolascapens@google.com> Kokoro-Presubmit: kokoro <noreply+kokoro@google.com> Tested-by: Stephen White <senorblanco@chromium.org>
