Various compile time improvements

Things done so far added Link Time Optimisation menu to the Digispark boards.
LTO seems to work and saves a few hundred bytes over standard builds.
Not all avr-gcc packages are built with the LTO module so you may get an error
if your build does not support it. Seek and ye shall find a better build!

Added a create disassembly recipe to the platform.txt to let us get an idea
what's going on under the hood in assembly language.

Added option to burn fuses using an ISP and the burn bootloader option
current fuses do NOT disable the RST pin to gain a PB5 GPIO pin as that
complicates life if one wants to build using an ISP instead of micronucleus
bootloader. Since we by default run at 16.5MHz I set BOD to 4.3V not the default
2.7V which is probably too low a voltage to run the ATTINY85 at 16.5MHz clock.

Author: Bezaleeluk

digistump-avr/boards.txt

@@ -1,22 +1,42 @@
 # See: http://code.google.com/p/arduino/wiki/Platforms
+# Added Link Time OPtimisation 2019
 
 menu.cpu=Processor
-
+menu.LTO=LTO (1.6.11+ only)
+menu.clock=Clock Speed
 ##############################################################
 
 
-
-
 digispark-tiny.name=Digispark (Default - 16.5mhz)
 digispark-tiny.upload.using=micronucleusprog
 digispark-tiny.upload.protocol=usb
 digispark-tiny.upload.tool=micronucleus
 digispark-tiny.upload.maximum_size=6012
+digispark-tiny.bootloader.tool=avrdude
+digispark-tiny.bootloader.unlock_bits=0xFF
+digispark-tiny.bootloader.lock_bits=0xFF
+digispark-tiny.bootloader.file=empty/empty_all.hex
+# efuse bit 0 /allow self program
+digispark-tiny.bootloader.extended_fuses=0xFE
+digispark-tiny.bootloader.high_fuses=0b11010100
+#digispark-tiny.menu.clock.16pll=16 MHz (PLL)
+digispark-tiny.bootloader.low_fuses=0xC1
+#digispark-tiny.menu.clock.16pll.build.f_cpu=16000000L
 digispark-tiny.build.mcu=attiny85
 digispark-tiny.build.f_cpu=16500000L
 digispark-tiny.build.board=AVR_DIGISPARK
 digispark-tiny.build.core=tiny
 digispark-tiny.build.variant=digispark
+digispark-tiny.menu.LTO.disable=Disabled
+digispark-tiny.menu.LTO.disable.ltocflags=
+digispark-tiny.menu.LTO.disable.ltoelfflags=
+digispark-tiny.menu.LTO.disable.ltocppflags=
+digispark-tiny.menu.LTO.disable.ltoarcmd=
+digispark-tiny.menu.LTO.enable=Enabled
+digispark-tiny.menu.LTO.enable.ltocflags=-flto -fno-fat-lto-objects
+digispark-tiny.menu.LTO.enable.ltoelfflags=-g -flto -fuse-linker-plugin
+digispark-tiny.menu.LTO.enable.ltocppflags=-flto
+digispark-tiny.menu.LTO.enable.ltoarcmd=gcc-
 digispark-tiny.upload.wait_for_upload_port = false
 digispark-tiny.upload.use_1200bps_touch = false
 digispark-tiny.upload.disable_flushing = false
@@ -32,6 +52,16 @@ digispark-pro.build.f_cpu=16000000L
 digispark-pro.build.board=AVR_DIGISPARKPRO
 digispark-pro.build.core=pro
 digispark-pro.build.variant=pro
+digispark-pro.menu.LTO.disable=Disabled
+digispark-pro.menu.LTO.disable.ltocflags=
+digispark-pro.menu.LTO.disable.ltoelfflags=
+digispark-pro.menu.LTO.disable.ltocppflags=
+digispark-pro.menu.LTO.disable.ltoarcmd=
+digispark-pro.menu.LTO.enable=Enabled
+digispark-pro.menu.LTO.enable.ltocflags=-flto -fno-fat-lto-objects
+digispark-pro.menu.LTO.enable.ltoelfflags=-g -flto -fuse-linker-plugin
+digispark-pro.menu.LTO.enable.ltocppflags=-flto
+digispark-pro.menu.LTO.enable.ltoarcmd=gcc-
 digispark-pro.upload.wait_for_upload_port = false
 digispark-pro.upload.use_1200bps_touch = false
 digispark-pro.upload.disable_flushing = false
@@ -46,6 +76,16 @@ digispark-pro32.build.f_cpu=16000000L
 digispark-pro32.build.board=AVR_DIGISPARKPRO
 digispark-pro32.build.core=pro
 digispark-pro32.build.variant=pro32buffer
+digispark-pro32.menu.LTO.disable=Disabled
+digispark-pro32.menu.LTO.disable.ltocflags=
+digispark-pro32.menu.LTO.disable.ltoelfflags=
+digispark-pro32.menu.LTO.disable.ltocppflags=
+digispark-pro32.menu.LTO.disable.ltoarcmd=
+digispark-pro32.menu.LTO.enable=Enabled
+digispark-pro32.menu.LTO.enable.ltocflags=-flto -fno-fat-lto-objects
+digispark-pro32.menu.LTO.enable.ltoelfflags=-g -flto -fuse-linker-plugin
+digispark-pro32.menu.LTO.enable.ltocppflags=-flto
+digispark-pro32.menu.LTO.enable.ltoarcmd=gcc-
 digispark-pro32.upload.wait_for_upload_port = false
 digispark-pro32.upload.use_1200bps_touch = false
 digispark-pro32.upload.disable_flushing = false
@@ -60,6 +100,16 @@ digispark-pro64.build.f_cpu=16000000L
 digispark-pro64.build.board=AVR_DIGISPARKPRO
 digispark-pro64.build.core=pro
 digispark-pro64.build.variant=pro64buffer
+digispark-pro64.menu.LTO.disable=Disabled
+digispark-pro64.menu.LTO.disable.ltocflags=
+digispark-pro64.menu.LTO.disable.ltoelfflags=
+digispark-pro64.menu.LTO.disable.ltocppflags=
+digispark-pro64.menu.LTO.disable.ltoarcmd=
+digispark-pro64.menu.LTO.enable=Enabled
+digispark-pro64.menu.LTO.enable.ltocflags=-flto -fno-fat-lto-objects
+digispark-pro64.menu.LTO.enable.ltoelfflags=-g -flto -fuse-linker-plugin
+digispark-pro64.menu.LTO.enable.ltocppflags=-flto
+digispark-pro64.menu.LTO.enable.ltoarcmd=gcc-
 digispark-pro64.upload.wait_for_upload_port = false
 digispark-pro64.upload.use_1200bps_touch = false
 digispark-pro64.upload.disable_flushing = false
@@ -74,6 +124,16 @@ digispark-tiny16.build.f_cpu=16000000L
 digispark-tiny16.build.board=AVR_DIGISPARK
 digispark-tiny16.build.core=tiny
 digispark-tiny16.build.variant=digispark
+digispark-tiny16.menu.LTO.disable=Disabled
+digispark-tiny16.menu.LTO.disable.ltocflags=
+digispark-tiny16.menu.LTO.disable.ltoelfflags=
+digispark-tiny16.menu.LTO.disable.ltocppflags=
+digispark-tiny16.menu.LTO.disable.ltoarcmd=
+digispark-tiny16.menu.LTO.enable=Enabled
+digispark-tiny16.menu.LTO.enable.ltocflags=-flto -fno-fat-lto-objects
+digispark-tiny16.menu.LTO.enable.ltoelfflags=-g -flto -fuse-linker-plugin
+digispark-tiny16.menu.LTO.enable.ltocppflags=-flto
+digispark-tiny16.menu.LTO.enable.ltoarcmd=gcc-
 digispark-tiny16.upload.wait_for_upload_port = false
 digispark-tiny16.upload.use_1200bps_touch = false
 digispark-tiny16.upload.disable_flushing = false
@@ -88,6 +148,16 @@ digispark-tiny8.build.f_cpu=8000000L
 digispark-tiny8.build.board=AVR_DIGISPARK
 digispark-tiny8.build.core=tiny
 digispark-tiny8.build.variant=digispark
+digispark-tiny8.menu.LTO.disable=Disabled
+digispark-tiny8.menu.LTO.disable.ltocflags=
+digispark-tiny8.menu.LTO.disable.ltoelfflags=
+digispark-tiny8.menu.LTO.disable.ltocppflags=
+digispark-tiny8.menu.LTO.disable.ltoarcmd=
+digispark-tiny8.menu.LTO.enable=Enabled
+digispark-tiny8.menu.LTO.enable.ltocflags=-flto -Fno-fat-lto-objects
+digispark-tiny8.menu.LTO.enable.ltoelfflags=-g -Flto -Fuse-linker-plugin
+digispark-tiny8.menu.LTO.enable.ltocppflags=-flto
+digispark-tiny8.menu.LTO.enable.ltoarcmd=gcc-
 digispark-tiny8.upload.wait_for_upload_port = false
 digispark-tiny8.upload.use_1200bps_touch = false
 digispark-tiny8.upload.disable_flushing = false
@@ -102,6 +172,16 @@ digispark-tiny1.build.f_cpu=1000000L
 digispark-tiny1.build.board=AVR_DIGISPARK
 digispark-tiny1.build.core=tiny
 digispark-tiny1.build.variant=digispark
+digispark-tiny1.menu.LTO.disable=Disabled
+digispark-tiny1.menu.LTO.disable.ltocflags=
+digispark-tiny1.menu.LTO.disable.ltoelfflags=
+digispark-tiny1.menu.LTO.disable.ltocppflags=
+digispark-tiny1.menu.LTO.disable.ltoarcmd=
+digispark-tiny1.menu.LTO.enable=Enabled
+digispark-tiny1.menu.LTO.enable.ltocflags=-flto -Fno-fat-lto-objects
+digispark-tiny1.menu.LTO.enable.ltoelfflags=-g -Flto -Fuse-linker-plugin
+digispark-tiny1.menu.LTO.enable.ltocppflags=-flto
+digispark-tiny1.menu.LTO.enable.ltoarcmd=gcc-
 digispark-tiny1.upload.wait_for_upload_port = false
 digispark-tiny1.upload.use_1200bps_touch = false
 digispark-tiny1.upload.disable_flushing = false

digistump-avr/platform.txt

@@ -4,6 +4,9 @@
 
 # For more info:
 # https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5---3rd-party-Hardware-specification
+# 2019 Added Link Time Optimisation possibility may require a newer more complete compiler
+# 2019 Added dissasembly output so we can debug / better optimise code and memory use
+
 
 name=Digistump AVR Boards
 version=1.5.4
@@ -14,16 +17,18 @@ version=1.5.4
 # Default "compiler.path" is correct, change only if you want to overidde the initial value
 compiler.path={runtime.tools.avr-gcc.path}/bin/
 compiler.c.cmd=avr-gcc
-compiler.c.flags=-c -g -Os -w -ffunction-sections -fdata-sections -MMD
-compiler.c.elf.flags=-Os -Wl,--gc-sections
+compiler.c.flags=-c -g -Os -w -ffunction-sections -fdata-sections -MMD {ltocflags}
+compiler.c.elf.flags=-Os {ltoelfflags} -Wl,--gc-sections
 compiler.c.elf.cmd=avr-gcc
-compiler.S.flags=-c -g -x assembler-with-cpp
+compiler.S.flags=-c -g -x assembler-with-cpp {ltocppflags}
 compiler.cpp.cmd=avr-g++
-compiler.cpp.flags=-c -g -Os -w -fno-exceptions -ffunction-sections -fdata-sections -MMD
-compiler.ar.cmd=avr-ar
+compiler.cpp.flags=-c -g -Os -w -fno-exceptions -ffunction-sections -fdata-sections -MMD {ltocppflags}
+compiler.ar.cmd=avr-{ltoarcmd}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.objdump.cmd=avr-objdump
+compiler.objdump.flags=--disassemble --source --line-numbers --demangle --section=.text
 compiler.elf2hex.flags=-O ihex -R .eeprom
 compiler.elf2hex.cmd=avr-objcopy
 compiler.ldflags=
@@ -54,6 +59,8 @@ recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.obj
 
 ## Create hex
 recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex"
+## Save disassembler listing
+recipe.hooks.objcopy.postobjcopy.1.pattern.windows=cmd /C "{compiler.path}{compiler.objdump.cmd}" {compiler.objdump.flags} "{build.path}/{build.project_name}.elf" > "{build.path}/{build.project_name}.lst"
 
 ## Save hex
 recipe.output.tmp_file={build.project_name}.hex
@@ -77,6 +84,19 @@ tools.micronucleus.upload.params.verbose=
 tools.micronucleus.upload.params.quiet=
 #tools.micronucleus.upload.pattern="{cmd.path}" --run --timeout 60 "{build.path}/{build.project_name}.hex"
 tools.micronucleus.upload.pattern="{cmd.path}" -cdigispark --timeout 60 -Uflash:w:{build.path}/{build.project_name}.hex:i
+
+tools.avrdude.path={runtime.tools.avrdude.path}
+tools.avrdude.cmd.path={path}/bin/avrdude
+tools.avrdude.config.path={runtime.platform.path}/avrdude.conf
+
+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 -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"
+
 
 # USB Default Flags
 # Default blank usb manufacturer will be filled it at compile time