diff --git a/CMakeLists.txt b/CMakeLists.txt index b381db8484..6cedae7de3 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -136,6 +136,10 @@ if(CONFIG_COMPILER_OPTIMIZATION_ASSERTIONS_DISABLE) list(APPEND compile_definitions "-DNDEBUG") endif() +if(CONFIG_COMPILER_NO_MERGE_CONSTANTS) + list(APPEND compile_options "-fno-merge-constants") +endif() + if(CONFIG_COMPILER_STACK_CHECK_MODE_NORM) list(APPEND compile_options "-fstack-protector") elseif(CONFIG_COMPILER_STACK_CHECK_MODE_STRONG) diff --git a/Kconfig b/Kconfig index f12b6a704c..06e6a970d1 100644 --- a/Kconfig +++ b/Kconfig @@ -510,6 +510,15 @@ mainmenu "Espressif IoT Development Framework Configuration" help Stack smashing protection. + config COMPILER_NO_MERGE_CONSTANTS + bool "Disable merging const sections" + depends on IDF_TOOLCHAIN_GCC + help + Disable merging identical constants (string/floating-point) across compilation units. + This helps in better size analysis of the application binary as the rodata section + distribution is more uniform across libraries. On downside, it may increase + the binary size and hence should be used during development phase only. + config COMPILER_WARN_WRITE_STRINGS bool "Enable -Wwrite-strings warning flag" default "n" diff --git a/docs/en/api-guides/tools/idf-size.rst b/docs/en/api-guides/tools/idf-size.rst index d456f5392e..0d5741621f 100644 --- a/docs/en/api-guides/tools/idf-size.rst +++ b/docs/en/api-guides/tools/idf-size.rst @@ -136,7 +136,7 @@ The table is sorted in descending order of the total contribution of the static .. note:: - The size of the ``.rodata`` section in the ``Flash Data`` memory type may appear very large for a single archive. This occurs due to linker relaxations. The linker may attempt to combine object file sections with ``MERGE`` and ``STRINGS`` flags from all archives into one to perform tail string optimization. Consequently, one archive may end up with a very large ``.rodata`` section, containing string literals from other archives. This is evident in the ``.rodata`` section of the ``libesp_app_format.a`` archive. + The size of the ``.rodata`` section in the ``Flash Data`` memory type may appear very large for a single archive. This occurs due to linker relaxations. The linker may attempt to combine object file sections with ``MERGE`` and ``STRINGS`` flags from all archives into one to perform tail string optimization. Consequently, one archive may end up with a very large ``.rodata`` section, containing string literals from other archives. This is evident in the ``.rodata`` section of the ``libesp_app_format.a`` archive. The specific compiler behavior here can be turned off by enabling :ref:`CONFIG_COMPILER_NO_MERGE_CONSTANTS` option (only for GCC toolchain), please read help for more details. Source File Usage Summary ``idf.py size-files`` diff --git a/tools/test_apps/system/build_test/sdkconfig.ci.no_merge_constants b/tools/test_apps/system/build_test/sdkconfig.ci.no_merge_constants new file mode 100644 index 0000000000..d30e4da72b --- /dev/null +++ b/tools/test_apps/system/build_test/sdkconfig.ci.no_merge_constants @@ -0,0 +1 @@ +CONFIG_COMPILER_NO_MERGE_CONSTANTS=y