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authorMasahiro Yamada <masahiroy@kernel.org>2020-06-14 23:43:41 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2020-06-17 10:38:42 +0900
commit4d0831e8a029c03f49f434f28b8faef9f0bd403f (patch)
treee092627794e9b75423b84dbf66b0221f862b6340 /scripts/Kconfig.include
parentf2f02ebd8f3833626642688b2d2c6a7b3c141fa9 (diff)
kconfig: unify cc-option and as-option
cc-option and as-option are almost the same; both pass the flag to $(CC). The main difference is the cc-option stops before the assemble stage (-S option) whereas as-option stops after (-c option). I chose -S because it is slightly faster, but $(cc-option,-gz=zlib) returns a wrong result (https://lkml.org/lkml/2020/6/9/1529). It has been fixed by commit 7b16994437c7 ("Makefile: Improve compressed debug info support detection"), but the assembler should always be invoked for more reliable compiler option tests. However, you cannot simply replace -S with -c because the following code in lib/Kconfig.debug would break: depends on $(cc-option,-gsplit-dwarf) The combination of -c and -gsplit-dwarf does not accept /dev/null as output. $ cat /dev/null | gcc -gsplit-dwarf -S -x c - -o /dev/null $ echo $? 0 $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o /dev/null objcopy: Warning: '/dev/null' is not an ordinary file $ echo $? 1 $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o tmp.o $ echo $? 0 There is another flag that creates an separate file based on the object file path: $ cat /dev/null | gcc -ftest-coverage -c -x c - -o /dev/null <stdin>:1: error: cannot open /dev/null.gcno So, we cannot use /dev/null to sink the output. Align the cc-option implementation with scripts/Kbuild.include. With -c option used in cc-option, as-option is unneeded. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'scripts/Kconfig.include')
-rw-r--r--scripts/Kconfig.include8
1 files changed, 1 insertions, 7 deletions
diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index c264da2b9b30..a5fe72c504ff 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -25,18 +25,12 @@ failure = $(if-success,$(1),n,y)
# $(cc-option,<flag>)
# Return y if the compiler supports <flag>, n otherwise
-cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -S -x c /dev/null -o /dev/null)
+cc-option = $(success,mkdir .tmp_$$$$; trap "rm -rf .tmp_$$$$" EXIT; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$$$/tmp.o)
# $(ld-option,<flag>)
# Return y if the linker supports <flag>, n otherwise
ld-option = $(success,$(LD) -v $(1))
-# $(as-option,<flag>)
-# /dev/zero is used as output instead of /dev/null as some assembler cribs when
-# both input and output are same. Also both of them have same write behaviour so
-# can be easily substituted.
-as-option = $(success, $(CC) $(CLANG_FLAGS) $(1) -c -x assembler /dev/null -o /dev/zero)
-
# $(as-instr,<instr>)
# Return y if the assembler supports <instr>, n otherwise
as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler -o /dev/null -)