Merge branch 'feature/cxx_rtti_preparation_v3_v4.0' into 'release/v4.0'

C++: re-add provisions for optional RTTI support (backport v4.0)

See merge request espressif/esp-idf!6557

components/cxx/CMakeLists.txt

@@ -7,3 +7,7 @@ target_link_libraries(${COMPONENT_LIB} INTERFACE "-u __cxa_guard_dummy")
 if(NOT CONFIG_COMPILER_CXX_EXCEPTIONS)
     target_link_libraries(${COMPONENT_LIB} INTERFACE "-u __cxx_fatal_exception")
 endif()
+
+if(NOT CONFIG_COMPILER_CXX_RTTI)
+    target_link_libraries(${COMPONENT_LIB} PUBLIC -fno-rtti)
+endif()

components/esp32/CMakeLists.txt

@@ -56,11 +56,6 @@ else()
         target_linker_script(${COMPONENT_LIB} INTERFACE "ld/esp32.extram.bss.ld")
     endif()
 
-    if(NOT CONFIG_COMPILER_CXX_RTTI)
-        # This has to be linked before esp32.project.ld
-        target_linker_script(${COMPONENT_LIB} INTERFACE "ld/esp32.discard-rtti.ld")
-    endif()
-
     # Process the template file through the linker script generation mechanism, and use the output for linking the
     # final binary
     target_linker_script(${COMPONENT_LIB} INTERFACE "${CMAKE_CURRENT_LIST_DIR}/ld/esp32.project.ld.in" 

components/esp32/component.mk

@@ -5,23 +5,18 @@
 COMPONENT_SRCDIRS := .
 
 ifdef CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
-	# This linker script must come before esp32.project.ld
+   # This linker script must come before esp32.project.ld
-	LINKER_SCRIPTS += esp32.extram.bss.ld
+   LINKER_SCRIPTS += esp32.extram.bss.ld
 endif
 
-ifndef CONFIG_COMPILER_CXX_RTTI
+#Linker scripts used to link the final application.
-	# This linker script must come before esp32.project.ld
+#Warning: These linker scripts are only used when the normal app is compiled; the bootloader
-	LINKER_SCRIPTS += esp32.discard-rtti.ld
+#specifies its own scripts.
-endif
-
-# Linker scripts used to link the final application.
-# Warning: These linker scripts are only used when the normal app is compiled; the bootloader
-# specifies its own scripts.
 LINKER_SCRIPTS += $(COMPONENT_BUILD_DIR)/esp32.project.ld esp32.peripherals.ld
 
-# ld_include_panic_highint_hdl is added as an undefined symbol because otherwise the
+#ld_include_panic_highint_hdl is added as an undefined symbol because otherwise the
-# linker will ignore panic_highint_hdl.S as it has no other files depending on any
+#linker will ignore panic_highint_hdl.S as it has no other files depending on any
-# symbols in it.
+#symbols in it.
 COMPONENT_ADD_LDFLAGS += -L $(COMPONENT_PATH)/ld \
                          -T esp32_out.ld \
                          -u ld_include_panic_highint_hdl \

components/esp32/ld/esp32.discard-rtti.ld

@@ -1,11 +0,0 @@
-/* This is only included if CONFIG_COMPILER_CXX_RTTI is not set, to
- * move RTTI sections of libstdc++ to an unused non-loadable memory region.
- */
-
-SECTIONS
-{
-  .rodata.discard-rtti (NOLOAD):
-  {
-    *libstdc++.a:(.rodata._ZTI* .rodata._ZTS*)
-  } > discard_seg
-}

components/esp32/ld/esp32.ld

@@ -86,11 +86,6 @@ MEMORY
   /* external memory ,including data and text */
   extern_ram_seg(RWX)  :             org = 0x3F800000,
                                      len = 0x400000
-
-  /* This is not a memory range which can really be accessed; we use it as a "bitbucket"
-     where non-loadable sections, which aren't used at run time, can be discarded.
-   */
-  discard_seg (R) :                  org = 0x00000000, len = 0x10000000
 }
 
 #if defined(CONFIG_ESP32_USE_FIXED_STATIC_RAM_SIZE)

make/project.mk

@@ -468,6 +468,7 @@ ifdef CONFIG_COMPILER_CXX_RTTI
 CXXFLAGS += -frtti
 else
 CXXFLAGS += -fno-rtti
+LDFLAGS += -fno-rtti
 endif
 
 ARFLAGS := cru