From 0e00c3da5c27845fd7d8ebdf39ac2d30da7c19fb Mon Sep 17 00:00:00 2001
From: Daniel Leung <daniel.leung@intel.com>
Date: Fri, 24 Feb 2023 17:11:18 -0800
Subject: [PATCH] linker: ld: see if compiler has a preferred linker

This asks the compiler if it has its own preference for ld.bfd.
This is useful for LLVM (when CONFIG_LLVM_USE_LD=y) so we know
which linker clang is using.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
---
 cmake/modules/FindGnuLd.cmake | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/cmake/modules/FindGnuLd.cmake b/cmake/modules/FindGnuLd.cmake
index c6c17471ed7..d698cc44246 100644
--- a/cmake/modules/FindGnuLd.cmake
+++ b/cmake/modules/FindGnuLd.cmake
@@ -20,16 +20,26 @@
 # Note that this will use CROSS_COMPILE, if defined,
 # as a prefix to the linker executable.
 
-if(DEFINED TOOLCHAIN_HOME)
-  # Search for linker under TOOLCHAIN_HOME if it is defined
-  # to limit which linker to use, or else we would be using
-  # host tools.
-  set(LD_SEARCH_PATH PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
-endif()
+# See if the compiler has a preferred linker
+execute_process(COMMAND ${CMAKE_C_COMPILER} --print-prog-name=ld.bfd
+                OUTPUT_VARIABLE GNULD_LINKER
+                OUTPUT_STRIP_TRAILING_WHITESPACE)
 
-find_program(GNULD_LINKER ${CROSS_COMPILE}ld.bfd ${LD_SEARCH_PATH})
-if(NOT GNULD_LINKER)
-  find_program(GNULD_LINKER ${CROSS_COMPILE}ld ${LD_SEARCH_PATH})
+if(NOT EXISTS "${GNULD_LINKER}")
+  # Need to clear it or else find_program() won't replace the value.
+  set(GNULD_LINKER)
+
+  if(DEFINED TOOLCHAIN_HOME)
+    # Search for linker under TOOLCHAIN_HOME if it is defined
+    # to limit which linker to use, or else we would be using
+    # host tools.
+    set(LD_SEARCH_PATH PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
+  endif()
+
+  find_program(GNULD_LINKER ${CROSS_COMPILE}ld.bfd ${LD_SEARCH_PATH})
+  if(NOT GNULD_LINKER)
+    find_program(GNULD_LINKER ${CROSS_COMPILE}ld ${LD_SEARCH_PATH})
+  endif()
 endif()
 
 if(GNULD_LINKER)