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authorNick Desaulniers <ndesaulniers@google.com>2021-08-16 13:25:01 -0700
committerMasahiro Yamada <masahiroy@kernel.org>2021-09-03 08:12:38 +0900
commit7d73c3e9c51400d3e0e755488050804e4d44737a (patch)
tree3bbf3a455d7e601f08f7b552f2949b54ef4dbe11 /Makefile
parent36f1386d341209bf5ec792938fbc0786b914f8dd (diff)
Makefile: remove stale cc-option checks
cc-option, cc-option-yn, and cc-disable-warning all invoke the compiler during build time, and can slow down the build when these checks become stale for our supported compilers, whose minimally supported versions increases over time. See Documentation/process/changes.rst for the current supported minimal versions (GCC 4.9+, clang 10.0.1+). Compiler version support for these flags may be verified on godbolt.org. The following flags are GCC only and supported since at least GCC 4.9. Remove cc-option and cc-disable-warning tests. * -fno-tree-loop-im * -Wno-maybe-uninitialized * -fno-reorder-blocks * -fno-ipa-cp-clone * -fno-partial-inlining * -femit-struct-debug-baseonly * -fno-inline-functions-called-once * -fconserve-stack The following flags are supported by all supported versions of GCC and Clang. Remove their cc-option, cc-option-yn, and cc-disable-warning tests. * -fno-delete-null-pointer-checks * -fno-var-tracking * -Wno-array-bounds The following configs are made dependent on GCC, since they use GCC specific flags. * READABLE_ASM * DEBUG_SECTION_MISMATCH -mfentry was not supported by s390-linux-gnu-gcc until gcc-9+, add a comment. --param=allow-store-data-races=0 was renamed to -fno-allow-store-data-races in the GCC 10 release; add a comment. -Wmaybe-uninitialized (GCC specific) was being added for CONFIG_GCOV, then again unconditionally; add it only once. Also, base RETPOLINE_CFLAGS and RETPOLINE_VDSO_CFLAGS on CONFIC_CC_IS_* then remove cc-option tests for Clang. Link: https://github.com/ClangBuiltLinux/linux/issues/1436 Acked-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile50
1 files changed, 31 insertions, 19 deletions
diff --git a/Makefile b/Makefile
index 891866af0787..ce5a297ecd7c 100644
--- a/Makefile
+++ b/Makefile
@@ -669,9 +669,10 @@ endif # KBUILD_EXTMOD
# Defaults to vmlinux, but the arch makefile usually adds further targets
all: vmlinux
-CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \
- $(call cc-option,-fno-tree-loop-im) \
- $(call cc-disable-warning,maybe-uninitialized,)
+CFLAGS_GCOV := -fprofile-arcs -ftest-coverage
+ifdef CONFIG_CC_IS_GCC
+CFLAGS_GCOV += -fno-tree-loop-im
+endif
export CFLAGS_GCOV
# The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.
@@ -679,12 +680,14 @@ ifdef CONFIG_FUNCTION_TRACER
CC_FLAGS_FTRACE := -pg
endif
-RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
-RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register
-RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
-RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline
-RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
-RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))
+ifdef CONFIG_CC_IS_GCC
+RETPOLINE_CFLAGS := $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
+RETPOLINE_VDSO_CFLAGS := $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register)
+endif
+ifdef CONFIG_CC_IS_CLANG
+RETPOLINE_CFLAGS := -mretpoline-external-thunk
+RETPOLINE_VDSO_CFLAGS := -mretpoline
+endif
export RETPOLINE_CFLAGS
export RETPOLINE_VDSO_CFLAGS
@@ -737,7 +740,7 @@ include/config/auto.conf:
endif # may-sync-config
endif # need-config
-KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
+KBUILD_CFLAGS += -fno-delete-null-pointer-checks
KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
@@ -752,17 +755,19 @@ KBUILD_CFLAGS += -Os
endif
# Tell gcc to never replace conditional load with a non-conditional one
+ifdef CONFIG_CC_IS_GCC
+# gcc-10 renamed --param=allow-store-data-races=0 to
+# -fno-allow-store-data-races.
KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)
KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races)
+endif
ifdef CONFIG_READABLE_ASM
# Disable optimizations that make assembler listings hard to read.
# reorder blocks reorders the control in the function
# ipa clone creates specialized cloned functions
# partial inlining inlines only parts of functions
-KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \
- $(call cc-option,-fno-ipa-cp-clone,) \
- $(call cc-option,-fno-partial-inlining)
+KBUILD_CFLAGS += -fno-reorder-blocks -fno-ipa-cp-clone -fno-partial-inlining
endif
ifneq ($(CONFIG_FRAME_WARN),0)
@@ -854,8 +859,10 @@ DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y)
endif
ifdef CONFIG_DEBUG_INFO_REDUCED
-DEBUG_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \
- $(call cc-option,-fno-var-tracking)
+DEBUG_CFLAGS += -fno-var-tracking
+ifdef CONFIG_CC_IS_GCC
+DEBUG_CFLAGS += -femit-struct-debug-baseonly
+endif
endif
ifdef CONFIG_DEBUG_INFO_COMPRESSED
@@ -889,6 +896,7 @@ ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
endif
endif
ifdef CONFIG_HAVE_FENTRY
+ # s390-linux-gnu-gcc did not support -mfentry until gcc-9.
ifeq ($(call cc-option-yn, -mfentry),y)
CC_FLAGS_FTRACE += -mfentry
CC_FLAGS_USING += -DCC_USING_FENTRY
@@ -901,7 +909,7 @@ endif
# We trigger additional mismatches with less inlining
ifdef CONFIG_DEBUG_SECTION_MISMATCH
-KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
+KBUILD_CFLAGS += -fno-inline-functions-called-once
endif
ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
@@ -980,14 +988,16 @@ KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
# We'll want to enable this eventually, but it's not going away for 5.7 at least
KBUILD_CFLAGS += $(call cc-disable-warning, zero-length-bounds)
-KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds)
+KBUILD_CFLAGS += -Wno-array-bounds
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow)
# Another good warning that we'll want to enable eventually
KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
# Enabled with W=2, disabled by default as noisy
-KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
+ifdef CONFIG_CC_IS_GCC
+KBUILD_CFLAGS += -Wno-maybe-uninitialized
+endif
# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS += -fno-strict-overflow
@@ -996,7 +1006,9 @@ KBUILD_CFLAGS += -fno-strict-overflow
KBUILD_CFLAGS += -fno-stack-check
# conserve stack if available
-KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
+ifdef CONFIG_CC_IS_GCC
+KBUILD_CFLAGS += -fconserve-stack
+endif
# Prohibit date/time macros, which would make the build non-deterministic
KBUILD_CFLAGS += -Werror=date-time