[LLVMdev] [cfe-dev] RFC: Codifying (but not formalizing) the optimization levels in LLVM and Clang

Renato Golin Linaro renato.golin at linaro.org
Mon Jan 14 06:41:48 PST 2013


On 14 January 2013 12:27, henry miller <hank at millerfarm.com> wrote:

> Would it be unreasonable to ask for a new/seperate set of optimizations:
> optimize debug. This would apple agressive optimizations, but not
> "significantly" changing the order of the code.
>

This will be interesting, but knowing how LLVM can segfault when commenting
out one or the other pass from a sequence, I'd think that it'd take a long
time before we could test *every* combination of these "nice to have"
 optimization profiles. Basically, you get all the tests we have today and
duplicate it for each profile.


I don't know the optimizer, but I know as a user of compilers that minimal
> optimization is often the difference between painfully slow program
> execution and okay performance. However debugging optimized programs can be
> difficult because the debugger jumps all over making the problem hard to
> understand.
>

I don't think you really need a performing debug image, though. Debuggers
tend to be so slow than the performance of the image is irrelevant.
Normally, the extra time is the number of breakpoints or watchpoints you
have set, and not the image itself... ;)

--renato
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