lkml.org 
[lkml]   [2022]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH v2 01/39] kbuild: Fix clang build
    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-13 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 make
    the CC variable DTRT, enabling one such as myself to use:

    $ make CC=clang-13

    This also lets one quickly test different clang versions.
    Additionally, also support path based LLVM suites like:

    $ make CC=/opt/llvm/bin/clang

    This changes the default to LLVM=1 when CC is clang, mixing toolchains
    is still possible by explicitly adding LLVM=0.

    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    ---
    Makefile | 45 +++++++++++++++++++++++++++---------
    tools/scripts/Makefile.include | 50 ++++++++++++++++++++++++++++-------------
    2 files changed, 68 insertions(+), 27 deletions(-)

    --- a/Makefile
    +++ b/Makefile
    @@ -423,9 +423,29 @@ HOST_LFS_CFLAGS := $(shell getconf LFS_C
    HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null)
    HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null)

    -ifneq ($(LLVM),)
    -HOSTCC = clang
    -HOSTCXX = clang++
    +# powerpc and s390 don't yet work with LLVM as a whole
    +ifeq ($(ARCH),powerpc)
    +LLVM = 0
    +endif
    +ifeq ($(ARCH),s390)
    +LLVM = 0
    +endif
    +
    +# otherwise, if CC=clang, default to using LLVM to enable LTO
    +CC_BASE := $(shell echo $(CC) | sed 's/.*\///')
    +CC_NAME := $(shell echo $(CC_BASE) | cut -b "1-5")
    +ifeq ($(shell test "$(CC_NAME)" = "clang"; echo $$?),0)
    +LLVM ?= 1
    +LLVM_PFX := $(shell echo $(CC) | sed 's/\(.*\/\)\?.*/\1/')
    +LLVM_SFX := $(shell echo $(CC_BASE) | cut -b "6-")
    +endif
    +
    +# if not set by now, do not use LLVM
    +LLVM ?= 0
    +
    +ifneq ($(LLVM),0)
    +HOSTCC = $(LLVM_PFX)clang$(LLVM_SFX)
    +HOSTCXX = $(LLVM_PFX)clang++$(LLVM_SFX)
    else
    HOSTCC = gcc
    HOSTCXX = g++
    @@ -442,15 +462,15 @@ KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS)

    # 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
    +ifneq ($(LLVM),0)
    +CC = $(LLVM_PFX)clang$(LLVM_SFX)
    +LD = $(LLVM_PFX)ld.lld$(LLVM_SFX)
    +AR = $(LLVM_PFX)llvm-ar$(LLVM_SFX)
    +NM = $(LLVM_PFX)llvm-nm$(LLVM_SFX)
    +OBJCOPY = $(LLVM_PFX)llvm-objcopy$(LLVM_SFX)
    +OBJDUMP = $(LLVM_PFX)llvm-objdump$(LLVM_SFX)
    +READELF = $(LLVM_PFX)llvm-readelf$(LLVM_SFX)
    +STRIP = $(LLVM_PFX)llvm-strip$(LLVM_SFX)
    else
    CC = $(CROSS_COMPILE)gcc
    LD = $(CROSS_COMPILE)ld
    @@ -461,6 +481,7 @@ OBJDUMP = $(CROSS_COMPILE)objdump
    READELF = $(CROSS_COMPILE)readelf
    STRIP = $(CROSS_COMPILE)strip
    endif
    +
    PAHOLE = pahole
    RESOLVE_BTFIDS = $(objtree)/tools/bpf/resolve_btfids/resolve_btfids
    LEX = flex
    --- a/tools/scripts/Makefile.include
    +++ b/tools/scripts/Makefile.include
    @@ -51,12 +51,32 @@ define allow-override
    $(eval $(1) = $(2)))
    endef

    -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)
    +# powerpc and s390 don't yet work with LLVM as a whole
    +ifeq ($(ARCH),powerpc)
    +LLVM = 0
    +endif
    +ifeq ($(ARCH),s390)
    +LLVM = 0
    +endif
    +
    +# otherwise, if CC=clang, default to using LLVM to enable LTO
    +CC_BASE := $(shell echo $(CC) | sed 's/.*\///')
    +CC_NAME := $(shell echo $(CC_BASE) | cut -b "1-5")
    +ifeq ($(shell test "$(CC_NAME)" = "clang"; echo $$?),0)
    +LLVM ?= 1
    +LLVM_PFX := $(shell echo $(CC) | sed 's/\(.*\/\)\?.*/\1/')
    +LLVM_SFX := $(shell echo $(CC_BASE) | cut -b "6-")
    +endif
    +
    +# if not set by now, do not use LLVM
    +LLVM ?= 0
    +
    +ifneq ($(LLVM),0)
    +$(call allow-override,CC,$(LLVM_PFX)clang$(LLVM_SFX))
    +$(call allow-override,AR,$(LLVM_PFX)llvm-ar$(LLVM_SFX))
    +$(call allow-override,LD,$(LLVM_PFX)ld.lld$(LLVM_SFX))
    +$(call allow-override,CXX,$(LLVM_PFX)clang++$(LLVM_SFX))
    +$(call allow-override,STRIP,$(LLVM_PFX)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)
    @@ -68,10 +88,10 @@ endif

    CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)

    -ifneq ($(LLVM),)
    -HOSTAR ?= llvm-ar
    -HOSTCC ?= clang
    -HOSTLD ?= ld.lld
    +ifneq ($(LLVM),0)
    +HOSTAR ?= $(LLVM_PFX)llvm-ar$(LLVM_SFX)
    +HOSTCC ?= $(LLVM_PFX)clang$(LLVM_SFX)
    +HOSTLD ?= $(LLVM_PFX)ld.lld$(LLVM_SFX)
    else
    HOSTAR ?= ar
    HOSTCC ?= gcc
    @@ -79,11 +99,11 @@ HOSTLD ?= ld
    endif

    # Some tools require Clang, LLC and/or LLVM utils
    -CLANG ?= clang
    -LLC ?= llc
    -LLVM_CONFIG ?= llvm-config
    -LLVM_OBJCOPY ?= llvm-objcopy
    -LLVM_STRIP ?= llvm-strip
    +CLANG ?= $(LLVM_PFX)clang$(LLVM_SFX)
    +LLC ?= $(LLVM_PFX)llc$(LLVM_SFX)
    +LLVM_CONFIG ?= $(LLVM_PFX)llvm-config$(LLVM_SFX)
    +LLVM_OBJCOPY ?= $(LLVM_PFX)llvm-objcopy$(LLVM_SFX)
    +LLVM_STRIP ?= $(LLVM_PFX)llvm-strip$(LLVM_SFX)

    ifeq ($(CC_NO_CLANG), 1)
    EXTRA_WARNINGS += -Wstrict-aliasing=3

    \
     
     \ /
      Last update: 2022-02-24 16:36    [W:4.197 / U:0.076 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site