[llvm] Reenable JumpTableToSwitch pass by default (PR #83229)

[David Spickett via llvm-commits]

DavidSpickett wrote:

With the pass disabled, or `JumpTableSizeThreshold` at 8 or below, compiling the file from https://github.com/llvm/llvm-project/pull/82546#issuecomment-1964186043 takes between 1 and 2 minutes.

`JumpTableSizeThreshold` 9, has, so far, taken 25 minutes. I'll leave it running and see what the final time is.

Which is not exactly nuanced but there it is. Perhaps that file only has tables of a certain size. Certainly this explains why lowering the threshold to 5 got further into the build, but then got stuck on another file that probably has a different distribution of sizes.

https://github.com/llvm/llvm-project/pull/83229