Optimization flags in qmake.spec

[Daniel J. Luke]

On Jun 11, 2007, at 9:38 AM, Jochen Küpper wrote:
> On 11.06.2007, at 11:02, Pierre Queinnec wrote:
>> IIRC Apple recommends -Os, not -O2.
>
> Why?
> Where is that documented?

I've seen it elsewhere, but in this link, the "Fastest, smallest"  
Xcode setting corresponds to -Os

http://developer.apple.com/documentation/Performance/Conceptual/ 
CodeFootprint/Articles/CompilerOptions.html

There's also discussion here:

http://developer.apple.com/tools/gcc_overview.html

Which mentions -
"When in doubt, it may be better to optimize for size, since smaller  
code may execute relatively faster. For example, large functions or  
loops containing data access patterns that do not exhibit a strong  
locality of reference may not fit into a processor's cache lines,  
which can lead to cache misses and subsequent fetches from memory.  
Smaller functions or loops with local data access stand a better  
chance of fitting in a given cache line and requiring fewer memory  
accesses."

--
Daniel J. Luke
+========================================================+
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