linux/arch/mips/loongson2ef/Platform
Nathan Chancellor d49fc69293 MIPS: Loongson{2ef,64}: Wrap -mno-branch-likely with cc-option
This flag is not supported by clang, which results in a warning:

  clang-14: warning: argument unused during compilation: '-mno-branch-likely' [-Wunused-command-line-argument]

This breaks cc-option, which adds -Werror to make this warning fatal and
catch flags that are not supported.

Wrap this flag in cc-option so that it does not cause cc-option to fail,
which can cause randconfigs to be really noisy, due to warnings not
getting disabled that should be.

Additionally, move the cc-option check to Kconfig so that the check is
done at configuration time, rather than build time, as builds with no
configuration change will be quicker because the cc-option call will not
need to happen in those instances.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2022-02-07 18:30:12 +01:00

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#
# Loongson Processors' Support
#
cflags-$(CONFIG_CPU_LOONGSON2EF) += -Wa,--trap
cflags-$(CONFIG_CPU_LOONGSON2E) += -march=loongson2e
cflags-$(CONFIG_CPU_LOONGSON2F) += -march=loongson2f
#
# Some versions of binutils, not currently mainline as of 2019/02/04, support
# an -mfix-loongson3-llsc flag which emits a sync prior to each ll instruction
# to work around a CPU bug (see __SYNC_loongson3_war in asm/sync.h for a
# description).
#
# We disable this in order to prevent the assembler meddling with the
# instruction that labels refer to, ie. if we label an ll instruction:
#
# 1: ll v0, 0(a0)
#
# ...then with the assembler fix applied the label may actually point at a sync
# instruction inserted by the assembler, and if we were using the label in an
# exception table the table would no longer contain the address of the ll
# instruction.
#
# Avoid this by explicitly disabling that assembler behaviour. If upstream
# binutils does not merge support for the flag then we can revisit & remove
# this later - for now it ensures vendor toolchains don't cause problems.
#
cflags-$(CONFIG_CPU_LOONGSON2EF) += $(call as-option,-Wa$(comma)-mno-fix-loongson3-llsc,)
# Enable the workarounds for Loongson2f
ifdef CONFIG_CPU_LOONGSON2F_WORKAROUNDS
cflags-$(CONFIG_CPU_NOP_WORKAROUNDS) += -Wa,-mfix-loongson2f-nop
cflags-$(CONFIG_CPU_JUMP_WORKAROUNDS) += -Wa,-mfix-loongson2f-jump
endif
# Some -march= flags enable MMI instructions, and GCC complains about that
# support being enabled alongside -msoft-float. Thus explicitly disable MMI.
cflags-y += $(call cc-option,-mno-loongson-mmi)
#
# Loongson Machines' Support
#
cflags-$(CONFIG_MACH_LOONGSON2EF) += -I$(srctree)/arch/mips/include/asm/mach-loongson2ef
cflags-$(CONFIG_CC_HAS_MNO_BRANCH_LIKELY) += -mno-branch-likely
load-$(CONFIG_LEMOTE_FULOONG2E) += 0xffffffff80100000
load-$(CONFIG_LEMOTE_MACH2F) += 0xffffffff80200000