Comparison SEGGER Toolchain and gcc with CMake

General

This article describes the use of the SEGGER toolchain (https://www.segger.com/products/development-tools/embedded-studio/technology/tools/segger-toolchain/) with CMake and showcases the code-size comparisons between the SEGGER toolchain and the ARM GCC toolchain.

We have based our internal testing on 3 different projects:

A FreeRTOS demo that runs on an Atmel/Microchip SAME70_Xplained Ultra board (see below for how to reproduce this on your own)
Our internal embench IOT benchmarking application
Our internal emPower OS demo application

The builds for all 3 demos have been done using the SEGGER compiler as well as the ARM GCC compiler.
A general guide on how to utilize the SEGGER CMake toolchain is available as a README.md file at https://github.com/SEGGERMicro/segger-toolchain-cmake

Build size comparison tables

The following tables summarize the results we have obtained.

A. Results for the FreeRTOS demo application
	Build Configuration	ARM GCC Code + RO Data	SEGGER Code + RO Data	abs. diff*	% diff*
Without LTO	Balanced w/o LTO	42 064	42 294	+230	+0.5%
Without LTO	Size-optimized w/o LTO	42 064	38 894	-3170	-7.5%
With LTO	Balanced with LTO	38 388	38 642	+254	+0.7%
With LTO	Size-optimized with LTO	38 388	34 192	-4196	-10.9%

B. Results for the embench IOT benchmarking application
	Build Configuration	ARM GCC Code + RO Data	SEGGER Code + RO Data	abs. diff*	% diff*
Without LTO	Balanced w/o LTO	102 060	102 137	+77	+0.1%
Without LTO	Size-optimized w/o LTO	102 060	94 687	-7373	-7.2%
With LTO	Balanced with LTO	88 496	88 749	+253	+0.3%
With LTO	Size-optimized with LTO	88 496	81 809	-6687	-7.6%

C. Results for the emPower OS demo application
	Build Configuration	ARM GCC Code + RO Data	SEGGER Code + RO Data	abs. diff*	% diff*
Without LTO	Balanced w/o LTO	658 622	629 956	-28666	-4.4%
Without LTO	Size-optimized w/o LTO	658 622	617 368	-41254	-6.3%
With LTO	Balanced with LTO	643 170	618 051	-25119	-3.9%
With LTO	Size-optimized with LTO	643 170	603 623	-39547	-6.1%

Notes:

(diff*): SEGGER build size minus ARM GCC build size
("Balanced") : using "-Os" optimization switch
("Size-optimized") : using "-Oz" optimization switch

Tool versions for comparison

Following versions have been used for the applications listed above:

SEGGER toolchain: version V8.25 2025070800.59551 - part of SEGGER Embedded Studio, obtainable at https://www.segger.com/downloads/embedded-studio
- Compiler version = 19.1.2

- Linker version = 4.44.2
ARM GCC toolchain: version 14.2.Rel1 - obtainable at https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
- Compiler version = 14.2.1

- Linker version = 2.43.1.20241119
SEGGER CMake toolchain: version 1.2.0 - obtainable at https://github.com/SEGGERMicro/segger-toolchain-cmake
ARM GCC CMake toolchain: version 02dbd14fc6e32aa568eaf8b200cef48b2c6d7b7d (main) - obtainable at https://github.com/vpetrigo/arm-cmake-toolchains.git

Reproducing the results for the FreeRTOS demo

Description of the FreeRTOS demo project

The demo project has been derived from the official FreeRTOS Demo from version 202411.00 and runs on the Atmel/Microchip SAME70_Xplained Ultra board
The original demo description is here http://www.freertos.org/Atmel_SAMV7_Cortex-M7_RTOS_Demo.html.

In comparison with the original demo code, our demo version comes with following changes:

some adaptations for the SEGGER compiler (e.g. for defining __inline__ macros, startup code etc.)
addition of CMakeLists.txt in order to build with both ARM GCC as well as SEGGER on the same code base (with exception of tool specific startup code)
redefinition of the GPIO-port for the blinking LED such that now LED3 is used.
mainCREATE_SIMPLE_BLINKY_DEMO_ONLY is set to 0: this ensures that the more comprehensive test-set is run as described under http://www.freertos.org/Atmel_SAMV7_Cortex-M7_RTOS_Demo.html

1-Stop ZIP package

A complete 1-stop ZIP package for the demo is available that includes the FreeRTOS kernel in addition to the demo project: Media:FreeRTOS_SGR_20250909_1000.zip

Instructions for the demo

Setup

Download the 1-stop ZIP package from Media:FreeRTOS_SGR_20250909_1000.zip
Unzip the package. This will yield a working folder called "FreeRTOS_SGR".
Under "FreeRTOS_SGR" there are following folders/files of interest:
- Source : this contains the FreeRTOS-kernel.
- Demo : this corresponds in function to the Demo folder found in the official FreeRTOS source code repository. In the demo package it contains only 2 subfolders:
  - Common : copy of the Common folder from the official FreeRTOS source code repository. Required for some basic demo functionality.
  
  - CORTEX_M7_SAME70_Xplained_AtmelStudio : the actuall demo application.
Install required compiler toolchains and other prerequisites:
- Install Ninja: https://ninja-build.org/
- Install CMake: version 3.24 or later: https://cmake.org/download
- Install SEGGER Embedded Studio V8.25: https://www.segger.com/downloads/embedded-studio
- For ARM GCC builds, install ARM GCC version 14.2.Rel1: https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Make sure the PATH environment variable contains the paths to the following:
- cmake executable (at least version 3.24)
- ninjaexecutable
- arm-none-eabi-gcc executable etc. (from your ARM GCC distribution)

Command-line usage

NOTE: issue these commands from within the FreeRTOS_SGR/Demo/CORTEX_M7_SAME70_Xplained_AtmelStudio subfolder!

Check which configuration-presets are available:

$ cmake --list-presets
Available configure presets:

  "sgr_flat_noipo"    - sgr_flat_noipo
  "sgr_flat_ipo"      - sgr_flat_ipo
  "armgcc_flat_noipo" - armgcc_flat_noipo
  "armgcc_flat_ipo"   - armgcc_flat_ipo

Check which build-presets are available (their name-endings indicate which kind of build-configurations they perform):

$ cmake --build --list-presets
Available build presets:

  "sgr_flat_noipo_dbg"
  "sgr_flat_noipo_rel"
  "sgr_flat_noipo_minsizerel"
  "sgr_flat_ipo_dbg"
  "sgr_flat_ipo_rel"
  "sgr_flat_ipo_minsizerel"
  "armgcc_flat_noipo_dbg"
  "armgcc_flat_noipo_rel"
  "armgcc_flat_noipo_minsizerel"
  "armgcc_flat_ipo_dbg"
  "armgcc_flat_ipo_rel"
  "armgcc_flat_ipo_minsizerel"

First execute the configuration step with

cmake --preset <config-preset-name>

Example:

$ cmake --preset sgr_flat_ipo
Preset CMake variables:

  CMAKE_CONFIGURATION_TYPES="MinSizeRel;Debug;Release"
  CMAKE_MAKE_PROGRAM="ninja"
  CMAKE_SYSTEM_PROCESSOR="arm-cortex-m7"
  CMAKE_TOOLCHAIN_FILE:FILEPATH="C:/WORK/DEV/PRJ/CMAKE/WRKSPC/FreeRTOS/FreeRTOS_SGR/Demo/CORTEX_M7_SAME70_Xplained_AtmelStudio/cmake_toolchains/segger-toolchain-cmake/segger-toolchain.cmake"
  PROJECT_ENABLE_IPO="1"
  PROJECT_FLAT_SOURCE_LIST="1"

-- CMAKE_MODULE_PATH extended by C:/WORK/DEV/PRJ/CMAKE/WRKSPC/FreeRTOS/FreeRTOS_SGR/Demo/CORTEX_M7_SAME70_Xplained_AtmelStudio/cmake_modules
-- The C compiler identification is SEGGERClang 19.1.2
-- Found binutils: arm-none-eabi
-- The CXX compiler identification is SEGGERClang 19.1.2
-- Found binutils: arm-none-eabi
-- The ASM compiler identification is SEGGERClang
-- Found binutils: arm-none-eabi
-- Found assembler: C:/Program Files/SEGGER/SEGGER Embedded Studio 8.25/bin/cc.exe
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Program Files/SEGGER/SEGGER Embedded Studio 8.25/bin/cc.exe - skipped
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files/SEGGER/SEGGER Embedded Studio 8.25/bin/cc++.exe - skipped
--
================================================================================================================
SEGGER_CMAKE_TOOLCHAIN_VERSION = 1.2.0
SEGGER_TOOLCHAIN_PKG_ROOT = C:/Program Files/SEGGER/SEGGER Embedded Studio 8.25
SEGGER_CMAKE_HAS_BUILTIN_COMPILER_ID = TRUE
CMAKE_SYSTEM_NAME = Generic
CMAKE_SYSTEM_PROCESSOR = arm-cortex-m7
Available build configuration types = MinSizeRel, Debug, Release
================================================================================================================

Then execute the build step with

cmake --build <build-preset-name>

Example:

$ cmake --build --preset sgr_flat_ipo_minsizerel
[22/47] Building C object CMakeFiles/CORTEX_M7_SAME70-FreeRTOS-Demo.dir/MinSizeRel/src/ASF/common/services/serial/usart_serial.o

Visual Studio Code (VS Code) usage

NOTE: open the FreeRTOS_SGR/Demo/CORTEX_M7_SAME70_Xplained_AtmelStudio subfolder as the workspace folder withing VS Code!

When opening the project folder in VS Code for the first time, the CMake extension pops up a drop-down list of configuration-presets to choose from.
The selected configuration-preset is shown in the extensions page. You may also choose another configuration-preset by clicking on the pencil icon.
The currently effective build-preset is shown in the extensions page. You may also choose another build-preset by clicking on the pencil icon.
Click on the build-icon on the "Build" section in order to build the associated artefacts.

Comparison SEGGER Toolchain and gcc with CMake

Contents

General

Build size comparison tables

Tool versions for comparison

Reproducing the results for the FreeRTOS demo

Description of the FreeRTOS demo project

1-Stop ZIP package

Instructions for the demo

Setup

Command-line usage

Visual Studio Code (VS Code) usage

Navigation menu

Comparison SEGGER Toolchain and gcc with CMake

General

Build size comparison tables

Tool versions for comparison

Reproducing the results for the FreeRTOS demo

Description of the FreeRTOS demo project

1-Stop ZIP package

Instructions for the demo

Setup

Command-line usage

Visual Studio Code (VS Code) usage

Navigation menu

Search