linux/scripts/Makefile.compiler

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# SPDX-License-Identifier: GPL-2.0-only
# cc-cross-prefix
# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
# Return first <prefix> where a <prefix>gcc is found in PATH.
# If no gcc found in PATH with listed prefixes return nothing
#
# Note: '2>/dev/null' is here to force Make to invoke a shell. Otherwise, it
# would try to directly execute the shell builtin 'command'. This workaround
# should be kept for a long time since this issue was fixed only after the
# GNU Make 4.2.1 release.
cc-cross-prefix = $(firstword $(foreach c, $(1), \
$(if $(shell command -v -- $(c)gcc 2>/dev/null), $(c))))
# output directory for tests below
TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$
# try-run
# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
# Exit code chooses option. "$$TMP" serves as a temporary file and is
# automatically cleaned up.
try-run = $(shell set -e; \
TMP=$(TMPOUT)/tmp; \
trap "rm -rf $(TMPOUT)" EXIT; \
mkdir -p $(TMPOUT); \
if ($(1)) >/dev/null 2>&1; \
then echo "$(2)"; \
else echo "$(3)"; \
fi)
# as-option
kbuild: Update assembler calls to use proper flags and language target as-instr uses KBUILD_AFLAGS, but as-option uses KBUILD_CFLAGS. This can cause as-option to fail unexpectedly when CONFIG_WERROR is set, because clang will emit -Werror,-Wunused-command-line-argument for various -m and -f flags in KBUILD_CFLAGS for assembler sources. Callers of as-option and as-instr should be adding flags to KBUILD_AFLAGS / aflags-y, not KBUILD_CFLAGS / cflags-y. Use KBUILD_AFLAGS in all macros to clear up the initial problem. Unfortunately, -Wunused-command-line-argument can still be triggered with clang by the presence of warning flags or macro definitions because '-x assembler' is used, instead of '-x assembler-with-cpp', which will consume these flags. Switch to '-x assembler-with-cpp' in places where '-x assembler' is used, as the compiler is always used as the driver for out of line assembler sources in the kernel. Finally, add -Werror to these macros so that they behave consistently whether or not CONFIG_WERROR is set. [nathan: Reworded and expanded on problems in commit message Use '-x assembler-with-cpp' in a couple more places] Link: https://github.com/ClangBuiltLinux/linux/issues/1699 Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Tested-by: Anders Roxell <anders.roxell@linaro.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-01-12 03:05:01 +00:00
# Usage: aflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
as-option = $(call try-run,\
kbuild: Add KBUILD_CPPFLAGS to as-option invocation After commit feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS"), there is an error while building certain PowerPC assembly files with clang: arch/powerpc/lib/copypage_power7.S: Assembler messages: arch/powerpc/lib/copypage_power7.S:34: Error: junk at end of line: `0b01000' arch/powerpc/lib/copypage_power7.S:35: Error: junk at end of line: `0b01010' arch/powerpc/lib/copypage_power7.S:37: Error: junk at end of line: `0b01000' arch/powerpc/lib/copypage_power7.S:38: Error: junk at end of line: `0b01010' arch/powerpc/lib/copypage_power7.S:40: Error: junk at end of line: `0b01010' clang: error: assembler command failed with exit code 1 (use -v to see invocation) as-option only uses KBUILD_AFLAGS, so after removing CLANG_FLAGS from KBUILD_AFLAGS, there is no more '--target=' or '--prefix=' flags. As a result of those missing flags, the host target will be tested during as-option calls and likely fail, meaning necessary flags may not get added when building assembly files, resulting in errors like seen above. Add KBUILD_CPPFLAGS to as-option invocations to clear up the errors. This should have been done in commit d5c8d6e0fa61 ("kbuild: Update assembler calls to use proper flags and language target"), which switched from using the assembler target to the assembler-with-cpp target, so flags that affect preprocessing are passed along in all relevant tests. as-option now mirrors cc-option. Fixes: feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS") Reported-by: Linux Kernel Functional Testing <lkft@linaro.org> Closes: https://lore.kernel.org/CA+G9fYs=koW9WardsTtora+nMgLR3raHz-LSLr58tgX4T5Mxag@mail.gmail.com/ Signed-off-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-06 22:40:35 +00:00
$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(1) -c -x assembler-with-cpp /dev/null -o "$$TMP",$(1),$(2))
# as-instr
kbuild: Update assembler calls to use proper flags and language target as-instr uses KBUILD_AFLAGS, but as-option uses KBUILD_CFLAGS. This can cause as-option to fail unexpectedly when CONFIG_WERROR is set, because clang will emit -Werror,-Wunused-command-line-argument for various -m and -f flags in KBUILD_CFLAGS for assembler sources. Callers of as-option and as-instr should be adding flags to KBUILD_AFLAGS / aflags-y, not KBUILD_CFLAGS / cflags-y. Use KBUILD_AFLAGS in all macros to clear up the initial problem. Unfortunately, -Wunused-command-line-argument can still be triggered with clang by the presence of warning flags or macro definitions because '-x assembler' is used, instead of '-x assembler-with-cpp', which will consume these flags. Switch to '-x assembler-with-cpp' in places where '-x assembler' is used, as the compiler is always used as the driver for out of line assembler sources in the kernel. Finally, add -Werror to these macros so that they behave consistently whether or not CONFIG_WERROR is set. [nathan: Reworded and expanded on problems in commit message Use '-x assembler-with-cpp' in a couple more places] Link: https://github.com/ClangBuiltLinux/linux/issues/1699 Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Tested-by: Anders Roxell <anders.roxell@linaro.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-01-12 03:05:01 +00:00
# Usage: aflags-y += $(call as-instr,instr,option1,option2)
as-instr = $(call try-run,\
printf "%b\n" "$(1)" | $(CC) -Werror $(CLANG_FLAGS) $(KBUILD_AFLAGS) -Wa$(comma)--fatal-warnings -c -x assembler-with-cpp -o "$$TMP" -,$(2),$(3))
# __cc-option
# Usage: MY_CFLAGS += $(call __cc-option,$(CC),$(MY_CFLAGS),-march=winchip-c6,-march=i586)
__cc-option = $(call try-run,\
$(1) -Werror $(2) $(3) -c -x c /dev/null -o "$$TMP",$(3),$(4))
# cc-option
# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
cc-option = $(call __cc-option, $(CC),\
$(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS),$(1),$(2))
# cc-option-yn
# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
cc-option-yn = $(call try-run,\
$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
# cc-disable-warning
# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
cc-disable-warning = $(call try-run,\
$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
# gcc-min-version
# Usage: cflags-$(call gcc-min-version, 70100) += -foo
gcc-min-version = $(call test-ge, $(CONFIG_GCC_VERSION), $1)
# clang-min-version
# Usage: cflags-$(call clang-min-version, 110000) += -foo
clang-min-version = $(call test-ge, $(CONFIG_CLANG_VERSION), $1)
# ld-option
# Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))