[PATCH v2 28/28] x86, build: allow LTO_CLANG and THINLTO to be selected

Sami Tolvanen
2020-09-03T20:34:02Z

Allow CONFIG_LTO_CLANG and CONFIG_THINLTO to be enabled.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
arch/x86/Kconfig | 2 ++
arch/x86/Makefile | 5 +++++
2 files changed, 7 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6de2e5c0bdba..0a49008c2363 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -92,6 +92,8 @@ config X86
select ARCH_SUPPORTS_ACPI
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
+ select ARCH_SUPPORTS_LTO_CLANG if X86_64
+ select ARCH_SUPPORTS_THINLTO if X86_64
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_USE_QUEUED_SPINLOCKS
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 4346ffb2e39f..49e3b8674eb5 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -173,6 +173,11 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
endif

+ifdef CONFIG_LTO_CLANG
+KBUILD_LDFLAGS += -plugin-opt=-code-model=kernel \
+ -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8)
+endif
+
# Workaround for a gcc prelease that unfortunately was shipped in a suse release
KBUILD_CFLAGS += -Wno-sign-compare
#
--
2.28.0.402.g5ffc5be6b7-goog