* use LTO in release builds
This significantly (40%) speeds up block replay and hashing - for example replaying first 1000
blocks, without/with LTO:
```
[arnetheduck@tempus ncli]$ ../env.sh nim c -d:release ncli_db
[arnetheduck@tempus ncli]$ ./ncli_db bench --db:db --network:medalla --slots:1000
Loaded 215006 blocks, head slot 307400
All time are ms
Average, StdDev, Min, Max, Samples, Test
Validation is turned off meaning that no BLS operations are performed
25468.481, 0.000, 25468.481, 25468.481, 1, Initialize DB
0.297, 0.516, 0.053, 13.645, 721, Load block from database
26.458, 0.000, 26.458, 26.458, 1, Load state from database
20.737, 8.288, 11.096, 199.325, 690, Apply block
333.069, 62.798, 45.225, 429.452, 31, Apply epoch block
0.000, 0.000, 0.000, 0.000, 0, Database block store
```
```
[arnetheduck@tempus ncli]$ ../env.sh nim c -d:release --passc:-flto --passl:-flto --stacktrace:off ncli_db
[arnetheduck@tempus ncli]$ ./ncli_db bench --db:db --network:medalla --slots:1000
Loaded 215006 blocks, head slot 307400
All time are ms
Average, StdDev, Min, Max, Samples, Test
Validation is turned off meaning that no BLS operations are performed
23903.006, 0.000, 23903.006, 23903.006, 1, Initialize DB
0.253, 0.122, 0.047, 0.731, 721, Load block from database
24.455, 0.000, 24.455, 24.455, 1, Load state from database
18.734, 7.062, 10.346, 167.397, 690, Apply block
194.869, 33.175, 29.311, 226.981, 31, Apply epoch block
```
Epoch processing is heavy on both arithmetics and hash caching, both of which get a
significant boost here.
This makes sense: nim creates lots of small functions spread out over many C files. A much
worse solution is to try to annotate code with `inline` - it copies functions to multiple
C files but still doesn't do intermodule optimizations significantly limiting the
compilers' ability to reason about the code, causing bloat and misrepresenting the usefulness
of a function to the call frequency analysis that drives actual (C-compiler) inlining and many
other optimizations.
In particular, many nim functions are part of `system` or the `C` backend - stack tracing,
memory allocation etc - nim's inlining system is pretty incomplete in that it does not deal
with these and many other cases.
* windows workaround
* skip LTO on windows for now
Ștefan Talpalaru
tersec
Mamy Ratsimbazafy
Giovanni Petrantoni
Sacha Saint-Leger
Kim De Mey
Viktor Kirilov
yslcrypto
Jacek Sieka
Zahary Karadjov
Eugene Kabanov