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How to Generate Map File Using Cmake?

6 minutes read

To generate a map file using CMake, you need to first enable the generation of map files during the compilation process. Map files provide information about the memory usage and function addresses in your compiled binary.


To enable map file generation in CMake, you can add the following lines to your CMakeLists.txt file:

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set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-Map=output.map")


This line adds the flag "-Wl,-Map=output.map" to the linker flags, which instructs the compiler to generate a map file named "output.map".


After adding this line to your CMakeLists.txt file, you can generate the map file by running the following commands in your build directory:

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cmake ..
make


Once the compilation is complete, you will find the generated map file in your build directory. You can analyze this map file to get insights into the memory usage and function addresses in your compiled binary.


How to set options for map file generation in cmake?

To set options for map file generation in CMake, you can use the CMAKE_EXE_LINKER_FLAGS variable to pass options to the linker. Here is an example of how you can set options for map file generation in CMake:

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# Set the linker flags to generate a map file
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-Map=output.map")

# Add your executable target
add_executable(my_executable main.cpp)

# Link your executable to generate the map file
target_link_libraries(my_executable)


In this example, we are setting the linker flags to generate a map file named output.map using the -Wl,-Map option. You can customize the options for map file generation according to your requirements.


How to customize map file generation in cmake?

To customize map file generation in CMake, you can use the CMAKE_MAP_FILE variable. Here is an example of how to specify a custom map file in your CMakeLists.txt file:

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# Set custom map file
set(CMAKE_MAP_FILE "${CMAKE_CURRENT_SOURCE_DIR}/custom_map_file.map")


You can also customize the map file generation further by using the add_custom_command function to run a script or command to generate the map file. Here is an example:

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# Generate map file using a custom command
add_custom_command(
    OUTPUT custom_map_file.map
    COMMAND generate_map_file.sh
    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
)

# Set custom map file
set(CMAKE_MAP_FILE "${CMAKE_CURRENT_SOURCE_DIR}/custom_map_file.map")


You can also customize the content of the map file by setting custom variables in your CMakeLists.txt file and then using them in the map file template. Here is an example:

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# Set custom variables
set(SYMBOL1 "symbol1")
set(SYMBOL2 "symbol2")

# Configure map file template
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/map_file_template.map ${CMAKE_CURRENT_BINARY_DIR}/custom_map_file.map @ONLY)

# Set custom map file
set(CMAKE_MAP_FILE "${CMAKE_CURRENT_BINARY_DIR}/custom_map_file.map")


By following these steps, you can easily customize map file generation in CMake to meet your specific requirements.


How to analyze memory usage with map files in cmake?

To analyze memory usage with map files in CMake, you can follow these steps:

  1. Enable generation of map files in your CMake build system by adding the following compiler flag to your CMakeLists.txt file:
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set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-Map=output.map")


  1. Build your project using CMake to generate the executable and the map file.
  2. Analyze the map file to understand the memory usage of your program. The map file contains information about memory usage, such as the size of each section of the executable, the memory address of each function and variable, and the size of each function and variable.
  3. Use tools like objdump or nm to analyze the map file and extract relevant information about memory usage.
  4. Look for sections of the map file that show high memory consumption and investigate ways to optimize memory usage in your code.


By following these steps, you can effectively analyze memory usage with map files in CMake and identify opportunities to optimize memory usage in your program.


How to extract information from map files in cmake?

To extract information from map files in CMake, you can use the file(STRINGS) command to read the contents of the map file and then process the data as needed. Here's a step-by-step guide on how to do this:

  1. Use the file(STRINGS) command to read the contents of the map file:
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file(STRINGS "path/to/mapfile.map" MAP_CONTENTS)


This command will read each line of the map file and store it in the variable MAP_CONTENTS.

  1. Process the contents of the map file as needed. For example, you can use regular expressions to extract specific information from the map file:
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foreach(line IN LISTS MAP_CONTENTS)
    if(line MATCHES "Symbol:\s+(\w+)")
        set(SYMBOL "${CMAKE_MATCH_1}")
        message("Found symbol: ${SYMBOL}")
    endif()
    # Add more processing logic here as needed
endforeach()


In this example, the regular expression "Symbol:\s+(\w+)" is used to extract symbols from the map file. You can adjust the regular expression based on the specific information you want to extract from the map file.

  1. Run your CMake script to extract and process information from the map file:
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cmake --build .


By following these steps, you can extract information from map files in CMake and process the data as needed in your CMake scripts.


What are common use cases for map files in cmake projects?

Map files in CMake projects are commonly used for the following use cases:

  1. Linker scripts: Map files can be used to customize the memory layout of an embedded system, by specifying the memory sections for different parts of the program (e.g. code, data, stack, etc.) and their corresponding memory addresses.
  2. Code size analysis: Map files provide detailed information about the size of each object file, function, and variable in the compiled executable, allowing developers to optimize code size and identify memory usage bottlenecks.
  3. Debugging: Map files can be used to locate the memory address of specific functions or variables in the compiled executable, enabling developers to debug issues related to memory corruption, stack overflow, or buffer overflows.
  4. Dependency analysis: Map files can be used to track the dependencies between different source files and libraries in a CMake project, helping developers understand the build process and identify circular dependencies or unnecessary dependencies.
  5. Optimization: Map files can be used to analyze the execution time of different functions in the compiled executable and identify performance bottlenecks that can be improved through code optimization or parallelization.


Overall, map files in CMake projects provide a valuable tool for developers to understand the memory layout, code size, and performance characteristics of their applications, and optimize them for better efficiency and reliability.


How to handle map files in cmake project?

In a CMake project, you can handle map files by adding them to your project as sources or resources just like any other file. Here are the steps to include map files in your CMake project:

  1. Create a folder in your project directory to store the map files (e.g., "maps").
  2. Place your map files in the folder.
  3. In your CMakeLists.txt file, use the add_executable or add_library command to add the map files to your project. For example:
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add_executable(my_project main.cpp map.cpp)


  1. If you need to specify the location of the map files, you can use the target_include_directories command to add the folder containing the map files to the include directories. For example:
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target_include_directories(my_project PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/maps)


  1. If the map files are required for the project to build or run, you can use the configure_file command to copy the map files to the build directory. For example:
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configure_file(${CMAKE_CURRENT_SOURCE_DIR}/maps/map1.txt ${CMAKE_CURRENT_BINARY_DIR}/map1.txt COPYONLY)


  1. Finally, you can access the map files in your code using their relative paths. For example, if you copied "map1.txt" to the build directory, you can open and read the file like this:
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#include <iostream>
#include <fstream>

int main() {
    std::ifstream file("map1.txt");
    if (file.is_open()) {
        // Read from the file
    } else {
        std::cout << "Error: Unable to open map file" << std::endl;
    }

    return 0;
}


By following these steps, you can easily handle map files in your CMake project.

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