From d156a5bf40f16b968152e80f6c9c63fe1f6ff1cc Mon Sep 17 00:00:00 2001
From: Aqua-sama <aqua@iserlohn-fortress.net>
Date: Mon, 15 Mar 2021 17:40:19 +0200
Subject: Enable ThinLTO

---
 linker.ld          | 2 +-
 makefile           | 5 +++--
 toolchain.makefile | 4 ++--
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/linker.ld b/linker.ld
index a9c6ec8..764b78b 100644
--- a/linker.ld
+++ b/linker.ld
@@ -51,7 +51,7 @@ SECTIONS
     .bss ALIGN(4K) : AT(ADDR(.bss) - VADDR_BASE + 4M) {
         begin_bss = .;
         *(.pages)
-        *(.bss)
+        *(.bss*)
         *(.stack)
         end_bss = .;
     }
diff --git a/makefile b/makefile
index 5be61c0..5ebde01 100644
--- a/makefile
+++ b/makefile
@@ -1,6 +1,6 @@
-include toolchain.makefile
 include .config
 OBJ_DIR != echo $(CONFIG_OBJ_DIR)
+include toolchain.makefile
 
 .PHONY: default clean test todo run menuconfig
 default: $(OBJ_DIR)/glitch.elf
@@ -18,7 +18,8 @@ CXX_SYSTEM_INCLUDE := $(addprefix -isystem, $(CXX_SYSTEM_INCLUDE))
 
 $(OBJ_DIR)/glitch.elf: $(autogen) $(AS_OBJ) $(CXX_OBJ) linker.ld
 	@echo "  LD   $@"
-	@$(LD) $(LD_FLAGS) -o $@ $(AS_OBJ) $(CXX_OBJ) -T $(CURDIR)/linker.ld
+	@mkdir -p $(OBJ_DIR)/thinlto_cache
+	@$(LD) $(LD_FLAGS) -o $@ $(AS_OBJ) $(CXX_OBJ)
 
 $(AS_OBJ): $(OBJ_DIR)/%.o: %.S
 	@mkdir -p $(@D)
diff --git a/toolchain.makefile b/toolchain.makefile
index c3ac2d8..d8f09f7 100644
--- a/toolchain.makefile
+++ b/toolchain.makefile
@@ -8,13 +8,13 @@ AS       := clang
 AS_FLAGS :=
 
 LD       := ld.lld
-LD_FLAGS :=
+LD_FLAGS := -T linker.ld --thinlto-cache-dir=$(OBJ_DIR)/thinlto_cache
 
 CXX         := clang++
 TEST_CXX    := clang++
 CXX_FLAGS   := -std=c++20 -g \
 	       -mkernel -ffreestanding -nostdlib -nostdinc -nostdinc++ \
-               -Wall -Wextra -Werror=pedantic -O2 \
+               -Wall -Wextra -Werror=pedantic -O2 -flto=thin \
 	       -Werror=date-time \
 	       -Werror=shadow-all \
 	       -Wold-style-cast -Wconversion \
-- 
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