At 7:17 PM +0100 12/20/14, René J.V. Bertin wrote:
Some of you may remember that I've wondered
aloud in the past why MacPorts clang (3.4) was
considerably slower than all other compilers,
while the Apple-provided almost-the-same clang
3.4 was considerably faster, in line with claims
about clang performance. Same for clang-3.4 on
Linux (i.e. not Apple provided): it is faster
than gcc.
Just now I noticed a possible explanation:
port variants llvm-3.6
llvm-3.6 has the variants:
[+]assertions: Enable assertions for error detection (has performance
impacts, especially on JIT)
So the default variant, and the only one
available as a binary package, is built to be
slow and crash upon certain errors.
Re the speed impact, it would be easy enough to
install with -assertions and do A-B tests to
quantitfy the difference.
Related, but an aside...the ability to have
multiple versions installed and switch among them
with port activate/deactivate is brilliant. :)
Craig
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