From: Andre Heider <a.heider@gmail.com>
Date: Sat, 28 Jan 2023 14:24:37 +0000 (+0100)
Subject: build: add a config knob to enable LTO for all packages
X-Git-Tag: v23.05.0-rc1~713
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=9ea7019ffd60ab3ef5a5654116fbc339f856482c;p=openwrt%2Fopenwrt.git

build: add a config knob to enable LTO for all packages

This enables LTO for all packages which haven't opted-out.

Signed-off-by: Andre Heider <a.heider@gmail.com>
---

diff --git a/config/Config-build.in b/config/Config-build.in
index f93ad37586..df2d9101ca 100644
--- a/config/Config-build.in
+++ b/config/Config-build.in
@@ -152,6 +152,13 @@ menu "Global build settings"
 		  garbage collection capabilites.
 		  Packages can choose to opt-out via setting PKG_BUILD_FLAGS:=no-gc-sections
 
+	config USE_LTO
+		bool
+		prompt "Use the link-time optimizer for all packages (EXPERIMENTAL)"
+		help
+		  Adds LTO flags to the CFLAGS and LDFLAGS.
+		  Packages can choose to opt-out via setting PKG_BUILD_FLAGS:=no-lto
+
 	config IPV6
 		def_bool y
 
diff --git a/include/package.mk b/include/package.mk
index 687f74edc1..d80f3bce49 100644
--- a/include/package.mk
+++ b/include/package.mk
@@ -56,7 +56,7 @@ ifeq ($(call pkg_build_flag,gc-sections,$(if $(CONFIG_USE_GC_SECTIONS),1,0)),1)
   TARGET_CXXFLAGS+= -ffunction-sections -fdata-sections
   TARGET_LDFLAGS+= -Wl,--gc-sections
 endif
-ifeq ($(call pkg_build_flag,lto,0),1)
+ifeq ($(call pkg_build_flag,lto,$(if $(CONFIG_USE_LTO),1,0)),1)
   TARGET_CFLAGS+= -flto=auto -fno-fat-lto-objects
   TARGET_CXXFLAGS+= -flto=auto -fno-fat-lto-objects
   TARGET_LDFLAGS+= -flto=auto -fuse-linker-plugin