Re: [eigen] Eigen code gets optimized away by avr-g++ - what to do?

[Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>]

On 29.06.2012 22:21, Ryan Pavlik wrote:
> However, I am now seeing quite strange behavior. It looks like Eigen code
> (and possibly the rest of the function in which it is used?) gets optimized
> out of the compiled binary.  (It's so efficient, it doesn't have any code!
> :D )  When built by the IDE, it uses -Os optimization (which is -O2 without
> the ones deemed to potentially enlarge the code) which triggers the issue.
> -O1 optimization doesn't seem to trigger it (by looking at the disassembly,
> I actually see a call to sqrtf when my test program calls .norm() on a
> vector) though I haven't actually run that code on a device.

The code looks simple enough that gcc can calculate the result of 
v1.norm() at compile-time. You should pass an unknown vector to the 
function, if you want see whether it actually does anything.

Christoph


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Dipl.-Inf. Christoph Hertzberg
Cartesium 0.049
Universität Bremen
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