[IR][X86] Move X86 specific portions of UpgradeIntrinsicFunction1 to a couple helper functions. NFC

This enables some early outs to avoid repeatedly using IsX86 check to qualify. I hope to continue to improve this to shorten the lengths of some of the string comparisons.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295424 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed