Why exceptions for error handling is so important

[via Digitalmars-d]

Just to be clear on this. Sandy Bridge and later have 16 x 256 
bits registers. There is really no reason for an optimizing 
compiler to not just stuff the whole exception value into 1 or 2 
of those in most cases where it has full control.

In the rare case where that is not enough, or possible, stuff it 
into a fixed TLS buffer (or a similar arrangement) and clear a 
signal value in that buffer when the exception is caught.