dmd foreach loops throw exceptions on invalid UTF sequences, use replacementDchar instead

[Walter Bright]

On 11/5/2021 2:43 PM, deadalnix wrote:
> I have not checked for GCC, but modern version of LLVM are pretty good at 
> optimizing in the presence of landing pads.

I saw a presentation by Chandler Carruth at CPPCON 3 years back or so where he 
said that LLVM abandoned much of the optimizations in the presence of rewind blocks.

Optimizations will do better, of course, if your tight loops don't call 
functions that might throw.

You'll also lose simply because the extra bulk of the EH code will push more of 
your hot code out of the cache.