Set the floating point status register as reserved
Summary:
This patch sets the FPSW (X87 floating-point status register) as a reserved
physical register and fix the test failure caused by [[ https://reviews.llvm.org/D68854| D68854 ]].
Before this patch, some tests will fail because it implicit uses FPSW without
define it. Setting the FPSW as a reserved physical register will skip liveness
analysis because it is always live.
Reviewers: pengfei, craig.topper
Reviewed By: craig.topper
Subscribers: craig.topper, hiraditya, llvm-commits
Patch by LiuChen.
Differential Revision: https://reviews.llvm.org/D69784