[llvm] [X86] Refine speed up checking clobbered FP/BP to make IPRA work. (PR #109246)

[Freddy Ye via llvm-commits]

FreddyLeaf wrote:

After more investigation, I realized spillFPBP has to be done before argument passing even IPRA is enabled. Considering there is a function containing e.g. 9 pointers as arguments, if there is a `push $rbp` after argument passing and before call function, the argument inside the function will not be passed correctly as it requires stack passing for the 7th, 8th, ... arguments. Closed,

https://github.com/llvm/llvm-project/pull/109246