LTO for esp32dev_8M

platform 6.6.0 has build-in support for "-flto" (link time optimization)

platformio.ini

@@ -268,7 +268,7 @@ AR_lib_deps = kosme/arduinoFFT @ 2.0.1
 ;;
 ;; please note that you can NOT update existing ESP32 installs with a "V4" build. Also updating by OTA will not work properly.
 ;; You need to completely erase your device (esptool erase_flash) first, then install the "V4" build from VSCode+platformio.
-platform = espressif32@ ~6.3.2
+platform = espressif32@ ~6.6.0                                             ;; supports -flto
 platform_packages = platformio/framework-arduinoespressif32 @ 3.20009.0    ;; select arduino-esp32 v2.0.9 (arduino-esp32 2.0.10 thru 2.0.14 are buggy so avoid them)
 build_flags = -g
   -Wshadow=compatible-local ;; emit warning in case a local variable "shadows" another local one
@@ -281,7 +281,7 @@ lib_deps =
 
 [esp32s2]
 ;; generic definitions for all ESP32-S2 boards
-platform = espressif32@ ~6.3.2
+platform = espressif32@ ~6.6.0                                             ;; supports -flto
 platform_packages = platformio/framework-arduinoespressif32 @ 3.20009.0    ;; select arduino-esp32 v2.0.9 (arduino-esp32 2.0.10 thru 2.0.14 are buggy so avoid them)
 build_flags = -g
   -DARDUINO_ARCH_ESP32
@@ -316,7 +316,7 @@ lib_deps =
 
 [esp32s3]
 ;; generic definitions for all ESP32-S3 boards
-platform = espressif32@ ~6.3.2
+platform = espressif32@ ~6.6.0                                             ;; supports -flto
 platform_packages = platformio/framework-arduinoespressif32 @ 3.20009.0    ;; select arduino-esp32 v2.0.9 (arduino-esp32 2.0.10 thru 2.0.14 are buggy so avoid them)
 build_flags = -g
   -DESP32
@@ -424,7 +424,9 @@ board = esp32dev
 platform = ${esp32_idf_V4.platform}
 platform_packages = ${esp32_idf_V4.platform_packages}
 build_unflags = ${common.build_unflags}
+  -fno-lto
 build_flags = ${common.build_flags} ${esp32_idf_V4.build_flags} -D WLED_RELEASE_NAME=ESP32_8M #-D WLED_DISABLE_BROWNOUT_DET
+  -g3 -ggdb -flto=auto ;; enable size optimization by the linker - comment out when debugging. ("=4" just means "use 4 cores in parallel")
   ${esp32.AR_build_flags}
 lib_deps = ${esp32_idf_V4.lib_deps}
   ${esp32.AR_lib_deps}
@@ -468,7 +470,9 @@ board_build.f_flash = 80000000L
 board_build.flash_mode = qio
 board_build.partitions = ${esp32.extended_partitions}
 build_unflags = ${common.build_unflags}
+  -fno-lto
 build_flags = ${common.build_flags} ${esp32_idf_V4.build_flags} -D WLED_RELEASE_NAME=ESP32_WROVER
+  -g3 -ggdb -flto=4 ;; enable size optimization by the linker - comment out when debugging. ("=4" just means "use 4 cores in parallel")
   -DBOARD_HAS_PSRAM -mfix-esp32-psram-cache-issue ;; Older ESP32 (rev.<3) need a PSRAM fix (increases static RAM used) https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-guides/external-ram.html
   -D DATA_PINS=25
   ${esp32.AR_build_flags}
@@ -540,7 +544,9 @@ platform = ${esp32s3.platform}
 platform_packages = ${esp32s3.platform_packages}
 upload_speed = 921600
 build_unflags = ${common.build_unflags}
+  -fno-lto
 build_flags = ${common.build_flags} ${esp32s3.build_flags} -D WLED_RELEASE_NAME=ESP32-S3_4M_qspi
+  -g3 -ggdb -flto=4 ;; enable size optimization by the linker - comment out when debugging. ("=4" just means "use 4 cores in parallel")
   -DARDUINO_USB_CDC_ON_BOOT=1 -DARDUINO_USB_MODE=1      ;; for boards with USB-OTG connector only (USBCDC or "TinyUSB")
   -DBOARD_HAS_PSRAM
   -DLOLIN_WIFI_FIX ; seems to work much better with this
@@ -561,7 +567,9 @@ board_build.partitions = ${esp32.default_partitions}
 board_build.flash_mode = qio
 board_build.f_flash = 80000000L
 build_unflags = ${common.build_unflags}
+  -fno-lto
 build_flags = ${common.build_flags} ${esp32s2.build_flags} -D WLED_RELEASE_NAME=ESP32-S2
+  -g3 -ggdb -flto=4 ;; enable size optimization by the linker - comment out when debugging. ("=4" just means "use 4 cores in parallel")
   -DARDUINO_USB_CDC_ON_BOOT=1
   -DARDUINO_USB_MSC_ON_BOOT=0
   -DARDUINO_USB_DFU_ON_BOOT=0