Re: Why Plan 9 C compilers don't have asm("")

From: Cort Dougan (
Date: Fri Jul 06 2001 - 03:38:35 EST

I'm talking about _modern_ processors, not processors that dominate the
modern age. This isn't x86. I don't believe that even aggressive
re-ordering will cause a serious hit in performance on function calls.
Unconditional branches are definitely predictable so icache pre-fetches are
not more complicated that straight-line code.

Measurement is more important, though. I've rejected a number of
optimizations from people (including many of my own) that were "obvious
enhancements" because of what they showed in real-world measurements. If
it doesn't run faster, despite the theory being "right", it's worthless.
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This archive was generated by hypermail 2b29 : Sat Jul 07 2001 - 21:00:17 EST