Download newer Clang toolchain and add it to PATH

Author: gsingh93

Makefile

@@ -2,6 +2,9 @@ ROOT_DIR := $(CURDIR)
 OUT_DIR := $(ROOT_DIR)/out
 SCRIPT_DIR := $(ROOT_DIR)/scripts
 CONFIG_DIR := $(ROOT_DIR)/config
+CLANG_DIR ?= $(ROOT_DIR)/toolchain/clang
+
+CLANG_URL := https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.6/clang+llvm-15.0.6-x86_64-linux-gnu-ubuntu-18.04.tar.xz
 
 SHARED_DIR := $(ROOT_DIR)/shared
 
@@ -138,6 +141,7 @@ else ifeq ($(ARCH),arm64)
 endif
 
 LINUX_MAKE := \
+  PATH=$(CLANG_DIR)/bin:$(PATH) \
   $(MAKE) \
   -C $(LINUX_SRC) \
   ARCH=$(ARCH) \
@@ -146,6 +150,12 @@ LINUX_MAKE := \
   V=$(VERBOSE) \
   O=$(LINUX_OUT)
 
+$(CLANG_DIR):
+	$(warning $(YELLOW)Clang directory $(CLANG_DIR) does not exist, downloading prebuilt binaries $(NC))
+	wget --no-verbose --show-progress $(CLANG_URL) -O clang.tar.xz
+	mkdir -p $(CLANG_DIR)
+	tar -xf clang.tar.xz -C $(CLANG_DIR) --strip-components=1
+
 .PHONY: linux_defconfig
 linux_defconfig $(LINUX_CONFIG): $(LINUX_CONFIG_FRAGMENT)
 	+ $(LINUX_MAKE) $(LINUX_DEFCONFIG)
@@ -158,7 +168,7 @@ linux_defconfig $(LINUX_CONFIG): $(LINUX_CONFIG_FRAGMENT)
 	$(SCRIPT_DIR)/check_merged_config.sh $(LINUX_CONFIG) $(LINUX_CONFIG_FRAGMENT)
 
 .PHONY: linux
-linux $(KERNEL_IMAGE): $(LINUX_CONFIG)
+linux $(KERNEL_IMAGE): $(LINUX_CONFIG) | $(CLANG_DIR)
 	+ $(LINUX_MAKE)
 	$(LINUX_SRC)/scripts/clang-tools/gen_compile_commands.py -d $(LINUX_OUT)
 

scripts/download_linux.sh

@@ -39,7 +39,7 @@ if [ $ACK -eq 0 ]; then
     echo "Downloading kernel version $VERSION"
 
     if [ $first_char -ge $MIN_VERSION ] && [ $first_char -le $MAX_VERSION ]; then
-        wget $LINUX_URL/v${first_char}.x/linux-$VERSION.tar.xz
+        wget --no-verbose --show-progress $LINUX_URL/v${first_char}.x/linux-$VERSION.tar.xz
         tar -xf linux-$VERSION.tar.xz
     else
         echo "$first_char is not a valid kernel major version number"