On 1 April 2014 19:35, Walter Bright <newshou...@digitalmars.com> wrote:
> Try this benchmark comparing various classification schemes:
GDC turns switches into table lookups, and speeds are comparable on my
system, though your little hack is appears faster in release builds.
Tests are with 1 million runs.
---
Non-release run:
Milliseconds 1797 1642 1501 1463
Non-release run, no bounds checking:
Milliseconds 1730 1611 1483 1512
Release run:
Milliseconds 1753 1633 1471 1528
Optimised run:
Milliseconds 0 0 0 0
---
It is interesting that switches seem to take longer when bounds
checking is turned off, and even longer when in release mode. However
this is not very conclusive as I can't test with optimisations turned
on. Unfortunately for your small program, gcc is too smart and
optimises everything away.
---
bool isIdentifierChar3(ubyte c)
{
switch(c)
{
case '0': .. case '9':
case 'A': .. case 'Z':
case 'a': .. case 'z':
case '$':
case '_':
return true;
default:
return false;
}
}
