Current implementation of built in function lookup uses autogenerated switch statements. Instead, use the perfect hash mapping to have the lookup use arrays instead. This will improve runtime performance. Bug: angleproject:3805 Change-Id: I6d0ba62d79abd53a7fe818fe675282800781f256 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1756883 Commit-Queue: Clemen Deng <clemendeng@google.com> Reviewed-by:Geoff Lang <geofflang@chromium.org>