If the toolchain will only be executed on the system where it is built (or a
system with the exact same CPU), this will squeeze out the last few (single
digit) percent of performance.

Signed-off-by: Rui Salvaterra <[email protected]>
---
 rules.mk            | 2 +-
 toolchain/Config.in | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/rules.mk b/rules.mk
index 3214395e1f..e416126030 100644
--- a/rules.mk
+++ b/rules.mk
@@ -249,7 +249,7 @@ export PKG_CONFIG
 HOSTCC:=gcc
 HOSTCXX:=g++
 HOST_CPPFLAGS:=-I$(STAGING_DIR_HOST)/include $(if 
$(IS_PACKAGE_BUILD),-I$(STAGING_DIR_HOSTPKG)/include 
-I$(STAGING_DIR)/host/include)
-HOST_CFLAGS:=-O2 $(HOST_CPPFLAGS)
+HOST_CFLAGS:=$(if $(CONFIG_BUILD_NATIVE_ARCH),-march=native) -O2 
$(HOST_CPPFLAGS)
 HOST_LDFLAGS:=-L$(STAGING_DIR_HOST)/lib $(if 
$(IS_PACKAGE_BUILD),-L$(STAGING_DIR_HOSTPKG)/lib -L$(STAGING_DIR)/host/lib)
 
 ifeq ($(CONFIG_EXTERNAL_TOOLCHAIN),)
diff --git a/toolchain/Config.in b/toolchain/Config.in
index cb557d4ad3..3149d7bc66 100644
--- a/toolchain/Config.in
+++ b/toolchain/Config.in
@@ -164,6 +164,14 @@ menuconfig TOOLCHAINOPTS
        bool "Toolchain Options"  if DEVEL
        depends on NEED_TOOLCHAIN
 
+config BUILD_NATIVE_ARCH
+       def_bool n
+       prompt "Build the toolchain with -march=native" if TOOLCHAINOPTS
+       help
+         When building the toolchain, optimize for the CPU in this specific 
machine.
+         Only choose Y if you're not going to run the compiled toolchain on 
any other
+         system.
+
 menuconfig EXTRA_TARGET_ARCH
        bool
        prompt "Enable an extra toolchain target architecture" if TOOLCHAINOPTS
-- 
2.29.2


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