[LLVMdev] Build Failure

dag at cray.com dag at cray.com
Thu Jan 3 08:58:47 PST 2013

Krzysztof Parzyszek <kparzysz at codeaurora.org> writes:

> The logic of the program may be such that the actual store (not the
> "pre-initialization") always happens before any uses, but the compiler
> may be unable to prove it.  In such case, the added initialization
> will extend the live range of the object and may result in a register
> spill.

I also want to note that this is exactly the kind of premature
optimization that Knuth warns about.  Is it really worth generating a
warning from the compiler to save 1-2 cycles in initialization code when
we don't even know that the (extremely slight) performance loss matters?


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