Arduino 1.6.x compiler options...

I'd noticed recently that since I'd upgraded the Arduino IDE to 1.6.x, some programs compiled and were smaller than they used to be. Great!

... the also don't run so fast... not so great.

After some googling around, the compiler options for optimisation had been changed.

So if you need something to compile and run quickly, you can.

Here's how to change it...

Navigate your way to the default Arduino directory in program files, and locate the platform.txt file

On my windows box, it's at C:\Program Files (x86)\Arduino\hardware\arduino\avr
On my Ubuntu box it's Home\Downloads\arduino-1.6.12\hardware\arduino\avr  (Why did I ./install.sh from the downloads folder!!!)

there's also one in the \hardware directory itself. That's not it!

Mine looks like this :

# Arduino AVR Core and platform. # ------------------------------ # # For more info: # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5-3rd-party-Hardware-specification name=Arduino AVR Boards version=1.6.14 # AVR compile variables # --------------------- compiler.warning_flags=-w compiler.warning_flags.none=-w compiler.warning_flags.default= compiler.warning_flags.more=-Wall compiler.warning_flags.all=-Wall -Wextra # Default "compiler.path" is correct, change only if you want to override the initial value compiler.path={runtime.tools.avr-gcc.path}/bin/ compiler.c.cmd=avr-gcc compiler.c.flags=-c -g -Os {compiler.warning_flags} -std=gnu11 -ffunction-sections -fdata-sections -MMD -flto -fno-fat-lto-objects compiler.c.elf.flags={compiler.warning_flags} -Os -flto -fuse-linker-plugin -Wl,--gc-sections compiler.c.elf.cmd=avr-gcc compiler.S.flags=-c -g -x assembler-with-cpp -flto compiler.cpp.cmd=avr-g++ compiler.cpp.flags=-c -g -Os {compiler.warning_flags} -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -flto compiler.ar.cmd=avr-gcc-ar compiler.ar.flags=rcs compiler.objcopy.cmd=avr-objcopy compiler.objcopy.eep.flags=-O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 compiler.elf2hex.flags=-O ihex -R .eeprom compiler.elf2hex.cmd=avr-objcopy compiler.ldflags= compiler.size.cmd=avr-size # This can be overridden in boards.txt build.extra_flags= # These can be overridden in platform.local.txt compiler.c.extra_flags= compiler.c.elf.extra_flags= compiler.S.extra_flags= compiler.cpp.extra_flags= compiler.ar.extra_flags= compiler.objcopy.eep.extra_flags= compiler.elf2hex.extra_flags= # AVR compile patterns # -------------------- ## Compile c files recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile c++ files recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile S files recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.S.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.S.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Create archives # archive_file_path is needed for backwards compatibility with IDE 1.6.5 or older, IDE 1.6.6 or newer overrides this value archive_file_path={build.path}/{archive_file} recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}" ## Combine gc-sections, archives, and objects recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} -mmcu={build.mcu} {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" {object_files} "{build.path}/{archive_file}" "-L{build.path}" -lm ## Create output files (.eep and .hex) recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.objcopy.eep.flags} {compiler.objcopy.eep.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.eep" recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex" ## Save hex recipe.output.tmp_file={build.project_name}.hex recipe.output.save_file={build.project_name}.{build.variant}.hex ## Compute size recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf" recipe.size.regex=^(?:\.text|\.data|\.bootloader)\s+([0-9]+).* recipe.size.regex.data=^(?:\.data|\.bss|\.noinit)\s+([0-9]+).* recipe.size.regex.eeprom=^(?:\.eeprom)\s+([0-9]+).* ## Preprocessor preproc.includes.flags=-w -x c++ -M -MG -MP recipe.preproc.includes="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.includes.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" preproc.macros.flags=-w -x c++ -E -CC recipe.preproc.macros="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.macros.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{preprocessed_file_path}" # AVR Uploader/Programmers tools # ------------------------------ tools.avrdude.path={runtime.tools.avrdude.path} tools.avrdude.cmd.path={path}/bin/avrdude tools.avrdude.config.path={path}/etc/avrdude.conf tools.avrdude.upload.params.verbose=-v tools.avrdude.upload.params.quiet=-q -q tools.avrdude.upload.params.noverify=-V tools.avrdude.upload.pattern="{cmd.path}" "-C{config.path}" {upload.verbose} {upload.verify} -p{build.mcu} -c{upload.protocol} -P{serial.port} -b{upload.speed} -D "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.program.params.verbose=-v tools.avrdude.program.params.quiet=-q -q tools.avrdude.program.params.noverify=-V tools.avrdude.program.pattern="{cmd.path}" "-C{config.path}" {program.verbose} {program.verify} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.erase.params.verbose=-v tools.avrdude.erase.params.quiet=-q -q tools.avrdude.erase.pattern="{cmd.path}" "-C{config.path}" {erase.verbose} -p{build.mcu} -c{protocol} {program.extra_params} -e -Ulock:w:{bootloader.unlock_bits}:m -Uefuse:w:{bootloader.extended_fuses}:m -Uhfuse:w:{bootloader.high_fuses}:m -Ulfuse:w:{bootloader.low_fuses}:m tools.avrdude.bootloader.params.verbose=-v tools.avrdude.bootloader.params.quiet=-q -q tools.avrdude.bootloader.pattern="{cmd.path}" "-C{config.path}" {bootloader.verbose} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{runtime.platform.path}/bootloaders/{bootloader.file}:i" -Ulock:w:{bootloader.lock_bits}:m tools.avrdude_remote.upload.pattern=/usr/bin/run-avrdude /tmp/sketch.hex {upload.verbose} -p{build.mcu} # USB Default Flags # Default blank usb manufacturer will be filled in at compile time # - from numeric vendor ID, set to Unknown otherwise build.usb_manufacturer="Unknown" build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'

Now I'd rename this to platform.old, so it's there if we screw it up, or wish to revert to slower, but more space-efficient code.

Now, open this file in your favorite text editor (mine's Notepad++ on windows) and do a find and replace on all instances of -Os (that's the letter O) and replace it with -O2 (again, the letter O) There are 3 instances of it in my file...

Bingo, save that as platform.txt in the directory, and you're done.

Here's my modified file...

# Arduino AVR Core and platform. # ------------------------------ # # For more info: # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5-3rd-party-Hardware-specification name=Arduino AVR Boards version=1.6.14 # AVR compile variables # --------------------- compiler.warning_flags=-w compiler.warning_flags.none=-w compiler.warning_flags.default= compiler.warning_flags.more=-Wall compiler.warning_flags.all=-Wall -Wextra # Default "compiler.path" is correct, change only if you want to override the initial value compiler.path={runtime.tools.avr-gcc.path}/bin/ compiler.c.cmd=avr-gcc compiler.c.flags=-c -g -O2 {compiler.warning_flags} -std=gnu11 -ffunction-sections -fdata-sections -MMD -flto -fno-fat-lto-objects compiler.c.elf.flags={compiler.warning_flags} -O2 -flto -fuse-linker-plugin -Wl,--gc-sections compiler.c.elf.cmd=avr-gcc compiler.S.flags=-c -g -x assembler-with-cpp -flto compiler.cpp.cmd=avr-g++ compiler.cpp.flags=-c -g -O2 {compiler.warning_flags} -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -flto compiler.ar.cmd=avr-gcc-ar compiler.ar.flags=rcs compiler.objcopy.cmd=avr-objcopy compiler.objcopy.eep.flags=-O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 compiler.elf2hex.flags=-O ihex -R .eeprom compiler.elf2hex.cmd=avr-objcopy compiler.ldflags= compiler.size.cmd=avr-size # This can be overridden in boards.txt build.extra_flags= # These can be overridden in platform.local.txt compiler.c.extra_flags= compiler.c.elf.extra_flags= compiler.S.extra_flags= compiler.cpp.extra_flags= compiler.ar.extra_flags= compiler.objcopy.eep.extra_flags= compiler.elf2hex.extra_flags= # AVR compile patterns # -------------------- ## Compile c files recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile c++ files recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Compile S files recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.S.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.S.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}" ## Create archives # archive_file_path is needed for backwards compatibility with IDE 1.6.5 or older, IDE 1.6.6 or newer overrides this value archive_file_path={build.path}/{archive_file} recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}" ## Combine gc-sections, archives, and objects recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} -mmcu={build.mcu} {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" {object_files} "{build.path}/{archive_file}" "-L{build.path}" -lm ## Create output files (.eep and .hex) recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.objcopy.eep.flags} {compiler.objcopy.eep.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.eep" recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex" ## Save hex recipe.output.tmp_file={build.project_name}.hex recipe.output.save_file={build.project_name}.{build.variant}.hex ## Compute size recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf" recipe.size.regex=^(?:\.text|\.data|\.bootloader)\s+([0-9]+).* recipe.size.regex.data=^(?:\.data|\.bss|\.noinit)\s+([0-9]+).* recipe.size.regex.eeprom=^(?:\.eeprom)\s+([0-9]+).* ## Preprocessor preproc.includes.flags=-w -x c++ -M -MG -MP recipe.preproc.includes="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.includes.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" preproc.macros.flags=-w -x c++ -E -CC recipe.preproc.macros="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {preproc.macros.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{preprocessed_file_path}" # AVR Uploader/Programmers tools # ------------------------------ tools.avrdude.path={runtime.tools.avrdude.path} tools.avrdude.cmd.path={path}/bin/avrdude tools.avrdude.config.path={path}/etc/avrdude.conf tools.avrdude.upload.params.verbose=-v tools.avrdude.upload.params.quiet=-q -q tools.avrdude.upload.params.noverify=-V tools.avrdude.upload.pattern="{cmd.path}" "-C{config.path}" {upload.verbose} {upload.verify} -p{build.mcu} -c{upload.protocol} -P{serial.port} -b{upload.speed} -D "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.program.params.verbose=-v tools.avrdude.program.params.quiet=-q -q tools.avrdude.program.params.noverify=-V tools.avrdude.program.pattern="{cmd.path}" "-C{config.path}" {program.verbose} {program.verify} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{build.path}/{build.project_name}.hex:i" tools.avrdude.erase.params.verbose=-v tools.avrdude.erase.params.quiet=-q -q tools.avrdude.erase.pattern="{cmd.path}" "-C{config.path}" {erase.verbose} -p{build.mcu} -c{protocol} {program.extra_params} -e -Ulock:w:{bootloader.unlock_bits}:m -Uefuse:w:{bootloader.extended_fuses}:m -Uhfuse:w:{bootloader.high_fuses}:m -Ulfuse:w:{bootloader.low_fuses}:m tools.avrdude.bootloader.params.verbose=-v tools.avrdude.bootloader.params.quiet=-q -q tools.avrdude.bootloader.pattern="{cmd.path}" "-C{config.path}" {bootloader.verbose} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{runtime.platform.path}/bootloaders/{bootloader.file}:i" -Ulock:w:{bootloader.lock_bits}:m tools.avrdude_remote.upload.pattern=/usr/bin/run-avrdude /tmp/sketch.hex {upload.verbose} -p{build.mcu} # USB Default Flags # Default blank usb manufacturer will be filled in at compile time # - from numeric vendor ID, set to Unknown otherwise build.usb_manufacturer="Unknown" build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'

You can now enjoy faster, but fatter sketches!

.. or not!