wip: build: add support for llvm clang

scripts/llext_link_helper.py

@@ -119,6 +119,11 @@ def main():
 
 		if (s_flags & (SH_FLAGS.SHF_WRITE | SH_FLAGS.SHF_ALLOC) ==
                     SH_FLAGS.SHF_WRITE | SH_FLAGS.SHF_ALLOC):
+			# .rodata may be marked writable by the Clang/objcopy LLEXT
+			# pipeline but should still be placed near .text for l32r reach
+			if s_name == '.rodata' or s_name.startswith('.rodata.'):
+				readonly.append(section)
+				continue
 			# .data, .bss or other writable sections
 			writable.append(section)
 			continue
@@ -181,17 +186,30 @@ def main():
 
 		dram_addr += section.header['sh_size']
 
-	start_addr = align_up(text_addr + text_size, 0x1000)
-
+	# Place readonly sections BEFORE .text so that Xtensa l32r instructions
+	# (which can only reach backwards up to 256KB) can access .rodata literals.
+	readonly_size = 0
+	for section in readonly:
+		readonly_size += align_up(section.header['sh_size'], section.header['sh_addralign'])
+	# Reserve space for readonly before .text
+	readonly_start = max_alignment(text_addr, 0x1000, 4)
+	text_addr = align_up(readonly_start + readonly_size, 0x1000)
+	# Now re-place .text at the updated address
+	command = [c for c in command if not c.startswith('-Wl,-Ttext=')]
+	command.append(f'-Wl,-Ttext=0x{text_addr:x}')
+
+	ro_addr = readonly_start
 	for section in readonly:
 		s_alignment = section.header['sh_addralign']
 		s_name = section.name
 
-		start_addr = align_up(start_addr, s_alignment)
+		ro_addr = align_up(ro_addr, s_alignment)
 
-		command.append(f'-Wl,--section-start={s_name}=0x{start_addr:x}')
+		command.append(f'-Wl,--section-start={s_name}=0x{ro_addr:x}')
 
-		start_addr += section.header['sh_size']
+		ro_addr += section.header['sh_size']
+
+	start_addr = align_up(text_addr + text_size, 0x1000)
 
 	start_addr = align_up(start_addr, 0x1000)
 

scripts/xtensa-build-zephyr.py

@@ -429,6 +429,16 @@ def parse_args():
 				help="Build menuconfig for target")
 	parser.add_argument("-z", "--zephyrsdk", required=False, action="store_true",
 				help="Force Build using Zephyr SDK for target")
+	parser.add_argument("--llvm-clang", required=False, type=pathlib.Path, default=None,
+				metavar="LLVM_BUILD_DIR",
+				help="""Use a custom LLVM/Clang build for C/ASM compilation instead of
+xt-clang or GCC. Specify the LLVM build directory containing bin/clang.
+A wrapper script is auto-generated to handle GCC flag translation,
+external assembler usage, and Xtensa target configuration.
+Example: --llvm-clang /home/user/llvm-project/build""")
+	parser.add_argument("--build-dir-suffix", default="",
+				help="Suffix to append to the build directory name (e.g. '-llvm' or '-gcc').\n"
+				     "This is useful for keeping side-by-side build environments.")
 
 	args = parser.parse_args()
 
@@ -822,6 +832,166 @@ def rimage_options(platform_dict):
 	return opts
 
 
+def generate_clang_wrapper(llvm_build_dir, platform, plat_config, top_dir):
+	"""Generate a clang wrapper script that translates GCC-only flags and
+	configures the external assembler for Xtensa targets.
+
+	The Zephyr build system passes several GCC-specific flags that clang
+	does not support. This wrapper filters those out, ensures the external
+	GCC assembler is used (clang's integrated asm doesn't support the full
+	Xtensa ISA), and adds the necessary -B/-I paths.
+
+	Returns the path to the generated wrapper script.
+	"""
+	llvm_build_dir = pathlib.Path(llvm_build_dir).resolve()
+	clang_bin = llvm_build_dir / "bin" / "clang"
+	if not clang_bin.exists():
+		raise FileNotFoundError(f"Clang not found at {clang_bin}")
+
+	# Derive the Zephyr SDK cross-compiler name from the board config
+	# e.g. "intel_adsp/ace30/ptl" -> "xtensa-intel_ace30_ptl_zephyr-elf"
+	# The Zephyr SDK naming uses the SoC name with underscores
+	board_parts = plat_config.replace("/", "_")
+	# Try to find the actual SDK cross-compiler directory
+	sdk_dir = os.environ.get("ZEPHYR_SDK_INSTALL_DIR", "")
+	cross_prefix = f"xtensa-{platform_configs[platform].XTENSA_CORE.split('_')[0]}"
+
+	# Find the GNU toolchain directory in the Zephyr SDK
+	gnu_dir = None
+	if sdk_dir:
+		sdk_path = pathlib.Path(sdk_dir)
+		# Look for the xtensa-*_zephyr-elf directory
+		for d in sdk_path.glob("gnu/xtensa-*_zephyr-elf"):
+			# Match based on platform name in the directory
+			if platform in str(d) or board_parts.split("_")[2] in str(d):
+				gnu_dir = d
+				break
+		# Fallback: try exact board-based name
+		if gnu_dir is None:
+			# Convert board config to SDK name
+			# intel_adsp/ace30/ptl -> intel_ace30_ptl
+			parts = plat_config.split("/")
+			if len(parts) >= 3:
+				sdk_name = f"{parts[1]}_{parts[2]}"
+			else:
+				sdk_name = parts[-1]
+			for d in sdk_path.glob(f"gnu/xtensa-*{sdk_name}*"):
+				gnu_dir = d
+				break
+
+	# Find the HAL SoC directory for core-isa.h
+	hal_soc_dir = None
+	modules_hal = top_dir / "modules" / "hal" / "xtensa"
+	if modules_hal.exists():
+		parts = plat_config.split("/")
+		if len(parts) >= 3:
+			soc_name = f"{parts[0].replace('intel_adsp', 'intel')}_{parts[1]}_{parts[2]}"
+		else:
+			soc_name = parts[-1]
+		for d in modules_hal.glob(f"zephyr/soc/*{parts[1]}*{parts[-1]}*"):
+			hal_soc_dir = d
+			break
+		# Fallback: try matching just the last part
+		if hal_soc_dir is None:
+			for d in modules_hal.glob(f"zephyr/soc/*{parts[-1]}*"):
+				hal_soc_dir = d
+				break
+
+	# Build the wrapper script
+	wrapper_dir = llvm_build_dir / "bin"
+	wrapper_path = wrapper_dir / f"clang-sof-wrapper-{platform}.sh"
+
+	# Determine target triple from GNU dir name
+	target_triple = ""
+	if gnu_dir:
+		# e.g. "xtensa-intel_ace30_ptl_zephyr-elf" from the dir name
+		target_triple = gnu_dir.name
+
+	# GCC compatibility queries must come before arg processing
+	gcc_compat = ""
+	if gnu_dir:
+		gcc_bin = gnu_dir / "bin" / f"{target_triple}-gcc"
+		gcc_compat = f"""
+# GCC compatibility: forward GCC-specific queries to the real GCC.
+# Zephyr's cmake toolchain detection calls -dumpfullversion,
+# --print-file-name, --print-multi-directory etc. which clang doesn't support.
+case "$1" in
+  -dumpversion|-dumpfullversion|-dumpmachine|\
+  --print-file-name=*|--print-multi-directory|--print-multi-lib|\
+  --print-libgcc-file-name|--print-search-dirs|-print-search-dirs|\
+  -print-multi-directory)
+    exec {gcc_bin} "$@"
+    ;;
+esac
+"""
+
+	wrapper_content = f"""#!/bin/bash
+# Auto-generated clang wrapper for SOF/{platform} builds
+# Generated by xtensa-build-zephyr.py --llvm-clang
+# Clang: {clang_bin}
+# Target: {target_triple}
+{gcc_compat}
+ARGS=()
+HAS_NO_INTEGRATED_AS=0
+HAS_TARGET=0
+for arg in "$@"; do
+  case "$arg" in
+    -fno-reorder-functions) ;;  # GCC only
+    -fno-defer-pop) ;;          # GCC only
+    --param=*) ;;               # GCC only
+    -fstrict-overflow) ;;       # deprecated GCC flag
+    -mlongcalls) ARGS+=("-mlong-calls") ;;  # translate
+    -fno-integrated-as) HAS_NO_INTEGRATED_AS=1; ARGS+=("$arg") ;;
+    --target=*) HAS_TARGET=1; ARGS+=("$arg") ;;
+    *) ARGS+=("$arg") ;;
+  esac
+done
+
+# Always use external assembler (clang integrated asm lacks full Xtensa ISA)
+if [ "$HAS_NO_INTEGRATED_AS" -eq 0 ]; then
+  ARGS+=("-fno-integrated-as")
+fi
+"""
+
+	if target_triple:
+		wrapper_content += f"""
+# Set Xtensa target if not already specified
+if [ "$HAS_TARGET" -eq 0 ]; then
+  ARGS+=("--target={target_triple}")
+fi
+"""
+
+	if hal_soc_dir:
+		core_isa_dir = hal_soc_dir / "xtensa" / "config"
+		if core_isa_dir.exists():
+			wrapper_content += f"""
+# core-isa.h lives in the SoC-specific HAL overlay, not alongside core.h
+ARGS+=("-I{core_isa_dir}")
+"""
+
+	if gnu_dir:
+		sysroot_bin = gnu_dir / target_triple / "bin"
+		gnu_bin = gnu_dir / "bin"
+		wrapper_content += f"""
+# Paths so clang can find the GCC external assembler and linker
+ARGS+=("-B{sysroot_bin}")
+ARGS+=("-B{gnu_bin}")
+"""
+
+	wrapper_content += f"""
+# Enable FLIX VLIW instruction bundling
+ARGS+=("-Xclang" "-target-feature" "-Xclang" "+flix")
+
+exec {clang_bin} "${{ARGS[@]}}"
+"""
+
+	with open(wrapper_path, "w") as f:
+		f.write(wrapper_content)
+	os.chmod(wrapper_path, 0o755)
+	print(f"Generated clang wrapper: {wrapper_path}")
+	return str(wrapper_path)
+
+
 STAGING_DIR = None
 def build_platforms():
 	global west_top, SOF_TOP
@@ -871,7 +1041,33 @@ def build_platforms():
 		_dict = dataclasses.asdict(platform_configs[platform])
 		platform_dict = { k:v for (k,v) in _dict.items() if _dict[k] is not None }
 
-		if args.zephyrsdk:
+		if args.llvm_clang:
+			print(f"Using LLVM/Clang from {args.llvm_clang}")
+			xtensa_tools_root_dir = None
+			# Use llvm toolchain variant for native Clang support with GCC assembler/linker
+			platf_build_environ["ZEPHYR_TOOLCHAIN_VARIANT"] = "llvm"
+			platf_build_environ["LLVM_TOOLCHAIN_PATH"] = str(pathlib.Path(args.llvm_clang).resolve())
+			# The llvm toolchain variant uses the Zephyr SDK's GNU Xtensa
+			# assembler/linker/sysroot. Zephyr's FindZephyr-sdk.cmake skips
+			# auto-discovery when ZEPHYR_TOOLCHAIN_VARIANT=llvm, so locate
+			# the SDK ourselves and export ZEPHYR_SDK_INSTALL_DIR if unset.
+			if not platf_build_environ.get("ZEPHYR_SDK_INSTALL_DIR"):
+				sdk_search = [pathlib.Path.home(), pathlib.Path("/opt"), pathlib.Path("/usr/local")]
+				sdks = []
+				for base in sdk_search:
+					if base.is_dir():
+						sdks.extend(base.glob("zephyr-sdk-*"))
+				# Prefer highest version (natural sort)
+				sdks = sorted((d for d in sdks if d.is_dir()),
+					      key=lambda p: p.name, reverse=True)
+				if sdks:
+					platf_build_environ["ZEPHYR_SDK_INSTALL_DIR"] = str(sdks[0])
+					print(f"Auto-detected ZEPHYR_SDK_INSTALL_DIR={sdks[0]}")
+				else:
+					print("WARNING: ZEPHYR_SDK_INSTALL_DIR not set and no zephyr-sdk-* "
+					      "directory found in $HOME, /opt, or /usr/local. "
+					      "LLVM Xtensa builds need the Zephyr SDK for binutils/sysroot.")
+		elif args.zephyrsdk:
 			print("Using Zephyr SDK for building")
 			xtensa_tools_root_dir = None
 		else:
@@ -915,7 +1111,7 @@ def build_platforms():
 			XTENSA_SYSTEM = str(builds_toolchainver / platform_dict["XTENSA_CORE"] / "config")
 			platf_build_environ["XTENSA_SYSTEM"] = XTENSA_SYSTEM
 
-		platform_build_dir_name = f"build-{platform}"
+		platform_build_dir_name = f"build-{platform}{args.build_dir_suffix}"
 
 		PLAT_CONFIG = platform_dict["PLAT_CONFIG"]
 
@@ -937,16 +1133,47 @@ def build_platforms():
 		if args.cmake_args:
 			build_cmd += args.cmake_args
 
+		# When using LLVM/Clang, the llvm toolchain variant handles:
+		# - Compiler detection via LLVM_TOOLCHAIN_PATH
+		# - GCC assembler/linker integration via CROSS_COMPILE
+		# - FLIX VLIW bundling via TOOLCHAIN_C_FLAGS
+		# - LLEXT shared library link wrapper
+		# No wrapper script or CMAKE_C_COMPILER override needed.
+		if args.llvm_clang:
+			# Set XTENSA_CORE_ID so cmake/toolchain/llvm/target.cmake
+			# selects the correct -mcpu for the LLVM backend.
+			# Platforms that share an SDK toolchain (e.g. NVL uses PTL's
+			# assembler) need an explicit CPU override for HiFi5 support.
+			parts = PLAT_CONFIG.split("/")
+			if len(parts) >= 3:
+				core_id = f"{parts[1]}_{parts[2]}"  # e.g. "ace40_nvl" -> "intel_ace40_adsp"
+				# Map board-level names to LLVM processor names
+				core_id_map = {
+					"ace30_ptl": "intel_ace30_adsp",
+					"ace40_nvl": "intel_ace40_adsp",
+					"ace40_nvls": "intel_ace40_adsp",
+				}
+				platf_build_environ["XTENSA_CORE_ID"] = core_id_map.get(core_id, "intel_ace30_adsp")
+
+				# Map board-level names to Zephyr SDK toolchain names
+				sdk_target_map = {
+					"ace30_ptl": "intel_ace30_ptl",
+					"ace40_nvl": "intel_ace30_ptl",
+					"ace40_nvls": "intel_ace30_ptl",
+				}
+				platf_build_environ["XTENSA_TOOLCHAIN_TARGET"] = sdk_target_map.get(core_id, f"intel_{core_id}")
+
 		extra_conf_files = [str(item.resolve(True)) for item in args.overlay]
 		# The '-d' option is a shortcut for '-o path_to_debug_overlay', we are good
 		# if both are provided, because it's no harm to merge the same overlay twice.
 		if args.debug:
 			extra_conf_files.append(str(pathlib.Path(SOF_TOP, "app", "debug_overlay.conf")))
 
-		# The xt-cland Cadence toolchain currently cannot link shared
+		# The xt-clang Cadence toolchain currently cannot link shared
 		# libraries for Xtensa. Therefore when it's used we switch to
-		# building relocatable ELF objects.
-		if platf_build_environ.get("ZEPHYR_TOOLCHAIN_VARIANT") == 'xt-clang':
+		# building relocatable ELF objects. We do the same for LLVM/Clang
+		# to match the xt-clang LLEXT format and avoid GOT/PLT overhead.
+		if platf_build_environ.get("ZEPHYR_TOOLCHAIN_VARIANT") == 'xt-clang' or args.llvm_clang:
 			extra_conf_files.append(str(pathlib.Path(SOF_TOP, "app", "llext_relocatable.conf")))
 
 		if extra_conf_files:
@@ -1173,7 +1400,7 @@ def install_lib(platform, sof_output_dir, abs_build_dir, platform_wconfig):
 def install_platform(platform, sof_output_dir, platf_build_environ, platform_wconfig):
 
 	# Keep in sync with caller
-	platform_build_dir_name = f"build-{platform}"
+	platform_build_dir_name = f"build-{platform}{args.build_dir_suffix}"
 
 	# Install to STAGING_DIR
 	abs_build_dir = pathlib.Path(west_top) / platform_build_dir_name / "zephyr"

src/audio/aria/aria_hifi3.c

@@ -5,7 +5,7 @@
 #include "aria.h"
 
 #if SOF_USE_HIFI(3, ARIA) || SOF_USE_HIFI(4, ARIA)
-#include <xtensa/config/defs.h>
+#include <xtensa/config/core-isa.h>
 #include <xtensa/tie/xt_hifi3.h>
 
 extern const int32_t sof_aria_index_tab[];

src/audio/aria/aria_hifi5.c

@@ -5,7 +5,7 @@
 #include "aria.h"
 
 #if SOF_USE_HIFI(5, ARIA)
-#include <xtensa/config/defs.h>
+#include <xtensa/config/core-isa.h>
 #include <xtensa/tie/xt_hifi5.h>
 
 extern const int32_t sof_aria_index_tab[];

src/audio/eq_fir/eq_fir_hifi2ep.c

@@ -13,7 +13,7 @@
 #include <sof/audio/buffer.h>
 #include <sof/audio/format.h>
 #include <sof/math/fir_hifi2ep.h>
-#include <xtensa/config/defs.h>
+#include <xtensa/config/core-isa.h>
 #include <xtensa/tie/xt_hifi2.h>
 #include <errno.h>
 #include <stddef.h>

src/audio/eq_fir/eq_fir_hifi3.c

@@ -12,7 +12,7 @@
 #include <sof/audio/module_adapter/module/generic.h>
 #include <sof/math/fir_hifi3.h>
 #include <user/fir.h>
-#include <xtensa/config/defs.h>
+#include <xtensa/config/core-isa.h>
 #include <xtensa/tie/xt_hifi3.h>
 #include <errno.h>
 #include <stddef.h>

src/audio/src/src_hifi2ep.c

@@ -12,7 +12,7 @@
 
 #include "src_common.h"
 
-#include <xtensa/config/defs.h>
+#include <xtensa/config/core-isa.h>
 #include <xtensa/tie/xt_hifi2.h>
 #include <stddef.h>
 #include <stdint.h>

src/audio/src/src_hifi3.c

@@ -12,7 +12,7 @@
 
 #include "src_common.h"
 
-#include <xtensa/config/defs.h>
+#include <xtensa/config/core-isa.h>
 #include <xtensa/tie/xt_hifi3.h>
 #include <stddef.h>
 #include <stdint.h>

src/audio/src/src_hifi4.c

@@ -14,7 +14,7 @@
 #include "src_common.h"
 
 #include <sof/math/numbers.h>
-#include <xtensa/config/defs.h>
+#include <xtensa/config/core-isa.h>
 #include <xtensa/tie/xt_hifi4.h>
 #include <stddef.h>
 #include <stdint.h>