cmake: Pass OPTIMIZATION_FLAG to linker too

The compiler may want to know the desired optimization level during
linking, as when the compiler multilib configuration includes -Os as a
selector.

Do this by adding a new (optional) linker function,
toolchain_linker_add_compiler_options, which maps compiler options to
equivalent linker options, discarding any that aren't applicable.

Linker configurations which use the compiler driver (ld, lld, and xt-ld)
apply all provided compiler options. Linkers which don't provide this
function fall back to an implementation which simply discards all options.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

CMakeLists.txt

@@ -242,6 +242,7 @@ endif()
 # Apply the final optimization flag(s)
 zephyr_compile_options($<$<COMPILE_LANGUAGE:C>:${OPTIMIZATION_FLAG}>)
 zephyr_compile_options($<$<COMPILE_LANGUAGE:CXX>:${OPTIMIZATION_FLAG}>)
+toolchain_linker_add_compiler_options(${OPTIMIZATION_FLAG})
 
 if(CONFIG_LTO)
   zephyr_compile_options($<TARGET_PROPERTY:compiler,optimization_lto>)

cmake/linker/ld/target.cmake

@@ -168,6 +168,14 @@ macro(toolchain_linker_finalize)
   set(CMAKE_CXX_LINK_EXECUTABLE "<CMAKE_CXX_COMPILER> <FLAGS> <CMAKE_CXX_LINK_FLAGS> ${cpp_link}")
 endmacro()
 
+# Function to map compiler flags into suitable linker flags
+# When using the compiler driver to run the linker, just pass
+# them all through
+
+function(toolchain_linker_add_compiler_options)
+  add_link_options(${ARGV})
+endfunction()
+
 # Load toolchain_ld-family macros
 include(${ZEPHYR_BASE}/cmake/linker/${LINKER}/target_relocation.cmake)
 include(${ZEPHYR_BASE}/cmake/linker/${LINKER}/target_configure.cmake)

cmake/linker/lld/target.cmake

@@ -128,6 +128,14 @@ macro(toolchain_linker_finalize)
  set(CMAKE_CXX_LINK_EXECUTABLE "<CMAKE_CXX_COMPILER> <FLAGS> <CMAKE_CXX_LINK_FLAGS> ${common_link}")
 endmacro()
 
+# Function to map compiler flags into suitable linker flags
+# When using the compiler driver to run the linker, just pass
+# them all through
+
+function(toolchain_linker_add_compiler_options)
+  add_link_options(${ARGV})
+endfunction()
+
 # Load toolchain_ld-family macros
 include(${ZEPHYR_BASE}/cmake/linker/ld/target_relocation.cmake)
 include(${ZEPHYR_BASE}/cmake/linker/ld/target_configure.cmake)

cmake/linker/target_template.cmake

@@ -11,3 +11,14 @@ if(NOT COMMAND toolchain_linker_finalize)
   macro(toolchain_linker_finalize)
   endmacro()
 endif()
+
+if(NOT COMMAND toolchain_linker_add_compiler_options)
+
+  # If the linker doesn't provide a method for mapping compiler options
+  # to linker options, then assume we can't. This matters when the linker
+  # is using additional compiler flags (like OPTIMIZATION_FLAG) when
+  # computing toolchain library paths.
+
+  function(toolchain_linker_add_compiler_options)
+  endfunction()
+endif()

cmake/linker/xt-ld/target.cmake

@@ -156,6 +156,14 @@ macro(toolchain_linker_finalize)
  set(CMAKE_CXX_LINK_EXECUTABLE "<CMAKE_CXX_COMPILER> <FLAGS> <CMAKE_CXX_LINK_FLAGS> ${common_link}")
 endmacro()
 
+# Function to map compiler flags into suitable linker flags
+# When using the compiler driver to run the linker, just pass
+# them all through
+
+function(toolchain_linker_add_compiler_options)
+  add_link_options(${ARGV})
+endfunction()
+
 # xt-ld is Xtensa's own version of binutils' ld.
 # So we can reuse most of the ld configurations.
 include(${ZEPHYR_BASE}/cmake/linker/ld/target_relocation.cmake)