Hello,
I notice that the Arduino IDE compiles Marlin (and any AVR code really) with 'size' optimization (-Os) set. Has anyone ever tried compiling Marlin for execution speed (-O2) instead ?
If so, did you notice any undue side effects ?
I've not tried running it on the board as yet as I'm still waiting for the controller board to arrive, but it strikes me that it's a much wanted change to make given the lack of desired MCU clock speed.
The location of the compiler optimization settings are in the file (in my case) is ..
C:\Program Files (x86)\Arduino\hardware\arduino\avr\platform.txt ... depends where you installed the IDE.
The two lines that I've changed to compile for execution speed are ..
compiler.c.flags=-c -g -Os {compiler.warning_flags} -std=gnu11 -ffunction-sections -fdata-sections -MMD -flto -fno-fat-lto-objects
and
compiler.cpp.flags=-c -g -Os {compiler.warning_flags} -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -MMD -flto
I've replaced the two -Os with -O2. It still compiles just fine, but that of cause doesn't mean it'll run fine - learn't this over many years of programming, sometimes it's fine, sometimes the odd routine in your code throws a wobberley with this setting (but can normally be overcome with slight coding adjustments).
If it runs OK, we may gain a good percentage increase in firmware execution speed (depends where the coding bottle necks are), then again, maybe not.
Pip
