LLVM: add built-in lld linker support for x86.

add support to use LLVM built-in lld linker to build
zephyr applications for x86 platforms.

Signed-off-by: Chen Peng1 <peng1.chen@intel.com>

cmake/linker/lld/target.cmake

@@ -107,7 +107,7 @@ endfunction(toolchain_ld_link_elf)
 
 
 # Load toolchain_ld-family macros
-include(${ZEPHYR_BASE}/cmake/linker/ld/target_base.cmake)
+include(${ZEPHYR_BASE}/cmake/linker/${LINKER}/target_base.cmake)
 include(${ZEPHYR_BASE}/cmake/linker/${LINKER}/target_baremetal.cmake)
 include(${ZEPHYR_BASE}/cmake/linker/ld/target_cpp.cmake)
 include(${ZEPHYR_BASE}/cmake/linker/ld/target_relocation.cmake)

cmake/linker/lld/target_baremetal.cmake

@@ -4,7 +4,7 @@
 
 macro(toolchain_ld_baremetal)
 
-  # LINKERFLAGPREFIX comes from linker/ld/target.cmake
+  # LINKERFLAGPREFIX comes from linker/lld/target.cmake
   zephyr_ld_options(
     -nostdlib
     -static
@@ -12,6 +12,13 @@ macro(toolchain_ld_baremetal)
     ${LINKERFLAGPREFIX},-N
   )
 
+  # Force LLVM to use built-in lld linker
+  if(NOT CONFIG_LLVM_USE_LD)
+    zephyr_ld_options(
+      -fuse-ld=lld
+  )
+  endif()
+
   # Funny thing is if this is set to =error, some architectures will
   # skip this flag even though the compiler flag check passes
   # (e.g. ARC and Xtensa). So warning should be the default for now.

cmake/linker/lld/target_base.cmake

@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: Apache-2.0
+
+# See root CMakeLists.txt for description and expectations of these macros
+
+macro(toolchain_ld_base)
+
+  if(NOT PROPERTY_LINKER_SCRIPT_DEFINES)
+    set_property(GLOBAL PROPERTY PROPERTY_LINKER_SCRIPT_DEFINES -D__GCC_LINKER_CMD__)
+  endif()
+
+  # TOOLCHAIN_LD_FLAGS comes from compiler/clang/target.cmake
+  # LINKERFLAGPREFIX comes from linker/lld/target.cmake
+  zephyr_ld_options(
+    ${TOOLCHAIN_LD_FLAGS}
+  )
+
+  zephyr_ld_options(
+    ${LINKERFLAGPREFIX},--gc-sections
+    ${LINKERFLAGPREFIX},--build-id=none
+  )
+
+  # Sort each input section by alignment.
+  zephyr_ld_option_ifdef(
+    CONFIG_LINKER_SORT_BY_ALIGNMENT
+    ${LINKERFLAGPREFIX},--sort-section=alignment
+  )
+
+endmacro()