scripts: add new SOF_CC_BASE={xcc,clang,gcc} variable

This is required to allow building XTOS with newer, clang-based, Cadence
toolchains as just submitted for ACP_7_0 in thesofproject#9351

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

scripts/cmake/xtensa-toolchain.cmake

@@ -49,11 +49,14 @@ set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
 # xt toolchain only partially follows gcc convention
 if(TOOLCHAIN STREQUAL "xt")
 	set(XCC 1)
-	set(CMAKE_C_COMPILER ${CROSS_COMPILE}xcc)
-else()
-	set(CMAKE_C_COMPILER ${CROSS_COMPILE}gcc)
 endif()
 
+if(NOT DEFINED SOF_CC_BASE)
+set(SOF_CC_BASE "gcc")
+endif()
+# e.g.: "xt-" + "xcc"
+set(CMAKE_C_COMPILER ${CROSS_COMPILE}${SOF_CC_BASE})
+
 find_program(CMAKE_LD NAMES "${CROSS_COMPILE}ld" PATHS ENV PATH NO_DEFAULT_PATH)
 find_program(CMAKE_AR NAMES "${CROSS_COMPILE}ar" PATHS ENV PATH NO_DEFAULT_PATH)
 find_program(CMAKE_RANLIB NAMES "${CROSS_COMPILE}ranlib" PATHS ENV PATH NO_DEFAULT_PATH)

scripts/set_xtensa_params.sh

@@ -145,6 +145,15 @@ case "$platform" in
 	;;
 esac
 
+# Pre-zephyr "XTOS" build
+case "$platform" in
+    none_yet)
+	SOF_CC_BASE='clang';;
+    *)
+	SOF_CC_BASE='xcc';;
+esac
+
+# For Zephyr unit tests, testbench,...
 case "$platform" in
     imx8*|mtl|lnl)
         ZEPHYR_TOOLCHAIN_VARIANT='xt-clang';;

scripts/xtensa-build-all.sh

@@ -231,6 +231,8 @@ do
 		PATH=$XTENSA_TOOLS_DIR/XtensaTools/bin:$OLDPATH
 		build_dir_suffix='xcc'
 	else
+		# Override SOF_CC_BASE from set_xtensa_params.sh
+		SOF_CC_BASE='gcc'
 		TOOLCHAIN=$HOST
 		PATH=$SOF_TOP/../$HOST/bin:$OLDPATH
 		build_dir_suffix='gcc'
@@ -248,6 +250,7 @@ do
 	printf 'PATH=%s\n' "$PATH"
 	( set -x # log the main commands and their parameters
 	cmake -DTOOLCHAIN="$TOOLCHAIN" \
+		-DSOF_CC_BASE="$SOF_CC_BASE" \
 		-DROOT_DIR="$ROOT" \
 		-DMEU_OPENSSL="${MEU_OPENSSL}" \
 		"${MEU_PATH_OPTION}" \