Interview Question 2: Find the largest bit in 64 bit number

Problem: You are asked to design a hardware which takes in a 64 bit number and finds out the largest position of  “1”.  For example if the input number is “00001010101111000” then the output should assert “1100” or 12 in decimal.

You can also dive deeper and find out corner cases and suggest how to fix them.
Also try to create solution which will be synthesis friendly and produces smallest and fastest solution.