From bfd037e87e56c7d308835e462b2cc2aca66dfacf Mon Sep 17 00:00:00 2001 From: Mahavir Jain Date: Fri, 12 Jul 2024 11:50:17 +0530 Subject: [PATCH] feat: add compiler config for not merging const sections Probably GCC-13.x and on-wards uses "-fmerge-constants" to merge the const section (string/floating-point) across compilation units. This makes it difficult to properly analyze the size output of rodata section across libraries, the merged section (big in size) is showed across a single library. The config option added here can help to disable this compiler behavior and help to provide better size analysis. It can be used during development phase only as it increases rodata section size. --- CMakeLists.txt | 4 ++++ Kconfig | 9 +++++++++ .../system/build_test/sdkconfig.ci.no_merge_constants | 1 + 3 files changed, 14 insertions(+) create mode 100644 tools/test_apps/system/build_test/sdkconfig.ci.no_merge_constants diff --git a/CMakeLists.txt b/CMakeLists.txt index cf7e42c8b7..2a78f92205 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 8768a086f2..1d9e813748 100644 --- a/Kconfig +++ b/Kconfig @@ -529,6 +529,15 @@ 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/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