Re: [PATCH] kbuild: Support clang-$ver builds
From: Masahiro Yamada <masahiroy@kernel.org>
Date: 2021-10-28 14:08:41
Also in:
linux-kbuild, lkml
On Thu, Oct 28, 2021 at 10:44 PM Peter Zijlstra [off-list ref] wrote:
Hi, Debian (and derived) distros ship their compilers as -$ver suffixed binaries. For gcc it is sufficent to use: $ make CC=gcc-12 However, clang builds (esp. clang-lto) need a whole array of tools to be exactly right, leading to unweildy stuff like: $ make CC=clang-13 LD=ld.lld=14 AR=llvm-ar-13 NM=llvm-nm-13 OBJCOPY=llvm-objcopy-13 OBJDUMP=llvm-objdump-13 READELF=llvm-readelf-13 STRIP=llvm-strip-13 LLVM=1 which is, quite franktly, totally insane and unusable. Instead use the already mandatory LLVM variable to convey this, enabling one such as myself to use: $ make LLVM=-13 This also lets one quickly test different clang versions.
Please read the commit log of a0d1c951ef08ed24f35129267e3595d86f57f5d3
quoted hunk ↗ jump to hunk
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- Makefile | 27 +++++++++++++++++---------- tools/scripts/Makefile.include | 23 +++++++++++++++-------- 2 files changed, 32 insertions(+), 18 deletions(-)diff --git a/Makefile b/Makefile index 30c7c81d0437..a38f38f7f190 100644 --- a/Makefile +++ b/Makefile@@ -423,9 +423,16 @@ HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null) HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null) HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null) +# When LLVM=-ver use clang-ver binaries, useful for Debian and other +# multi-version setups +ifeq ($(shell test $(LLVM) -lt 0; echo $$?),0) +LLVM_SFX=$(LLVM) +export LLVM_SFX +endif + ifneq ($(LLVM),) -HOSTCC = clang -HOSTCXX = clang++ +HOSTCC = clang$(LLVM_SFX) +HOSTCXX = clang++$(LLVM_SFX) else HOSTCC = gcc HOSTCXX = g++@@ -443,14 +450,14 @@ KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS) $(HOSTLDLIBS) # Make variables (CC, etc...) CPP = $(CC) -E ifneq ($(LLVM),) -CC = clang -LD = ld.lld -AR = llvm-ar -NM = llvm-nm -OBJCOPY = llvm-objcopy -OBJDUMP = llvm-objdump -READELF = llvm-readelf -STRIP = llvm-strip +CC = clang$(LLVM_SFX) +LD = ld.lld$(LLVM_SFX) +AR = llvm-ar$(LLVM_SFX) +NM = llvm-nm$(LLVM_SFX) +OBJCOPY = llvm-objcopy$(LLVM_SFX) +OBJDUMP = llvm-objdump$(LLVM_SFX) +READELF = llvm-readelf$(LLVM_SFX) +STRIP = llvm-strip$(LLVM_SFX) else CC = $(CROSS_COMPILE)gcc LD = $(CROSS_COMPILE)lddiff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include index 071312f5eb92..a2b53cc91378 100644 --- a/tools/scripts/Makefile.include +++ b/tools/scripts/Makefile.include@@ -51,12 +51,19 @@ define allow-override $(eval $(1) = $(2))) endef +# When LLVM=-ver use clang-ver binaries, useful for Debian and other +# multi-version setups +ifeq ($(shell test $(LLVM) -lt 0; echo $$?),0) +LLVM_SFX=$(LLVM) +export LLVM_SFX +endif + ifneq ($(LLVM),) -$(call allow-override,CC,clang) -$(call allow-override,AR,llvm-ar) -$(call allow-override,LD,ld.lld) -$(call allow-override,CXX,clang++) -$(call allow-override,STRIP,llvm-strip) +$(call allow-override,CC,clang$(LLVM_SFX)) +$(call allow-override,AR,llvm-ar$(LLVM_SFX)) +$(call allow-override,LD,ld.lld$(LLVM_SFX)) +$(call allow-override,CXX,clang++$(LLVM_SFX)) +$(call allow-override,STRIP,llvm-strip$(LLVM_SFX)) else # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix. $(call allow-override,CC,$(CROSS_COMPILE)gcc)@@ -69,9 +76,9 @@ endif CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?) ifneq ($(LLVM),) -HOSTAR ?= llvm-ar -HOSTCC ?= clang -HOSTLD ?= ld.lld +HOSTAR ?= llvm-ar$(LLVM_SFX) +HOSTCC ?= clang$(LLVM_SFX) +HOSTLD ?= ld.lld$(LLVM_SFX) else HOSTAR ?= ar HOSTCC ?= gcc
-- Best Regards Masahiro Yamada