[CodeGen] Fix the branch probability assertion in r318202

Due to integer precision, we might have numerator greater than denominator in
the branch probability scaling. Add a check to prevent this from happening.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318353 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed