Show how ThinLTO can be supported

Makefile

@@ -16,9 +16,16 @@ CPP_FILES += ext/EASTL/source/allocator_eastl.cpp ext/EASTL/source/assert.cpp \
 							ext/EASTL/source/intrusive_list.cpp ext/EASTL/source/numeric_limits.cpp \
 							ext/EASTL/source/red_black_tree.cpp ext/EASTL/source/string.cpp
 
-GDEFS = -DEASTL_SIZE_T_32BIT=1
+GDEFS =
+OPTIMIZE = -O2
 
-OPTIONS=-m32 -msse3 $(INCLUDE) $(GDEFS)
+## to enable ThinLTO use these ##
+#CC=.../clang-trunk/bin/clang-5.0
+#CXX=.../clang-trunk/bin/clang++-5.0
+#LD=ld.lld-5.0
+#LTO_DEFS=-flto=thin
+
+OPTIONS=-m32 -msse3 $(INCLUDE) $(GDEFS) $(OPTIMIZE) $(LTO_DEFS)
 WARNS=-Wall -Wextra -pedantic
 COMMON=-ffreestanding -nostdlib -MMD -fstack-protector-strong $(OPTIONS) $(WARNS)
 LDFLAGS=-static -nostdlib -melf_i386 --strip-all --script=src/linker.ld

README.md

@@ -16,6 +16,8 @@
 - Stack protector support
 - EASTL C++ support, which has many useful containers
 - Entire machine image is 32kb (8k without EASTL)
+- ThinLTO support if you build your own clang toolchain from trunk
+    - Machine image goes from 32kb to 11kb with LTO
 
 ## Goal
 

src/crt/c_abi.c

@@ -30,6 +30,7 @@ void __stack_chk_fail_local()
   panic("Stack protector: Canary modified");
   __builtin_unreachable();
 }
+__attribute__((used))
 void __stack_chk_fail()
 {
   panic("Stack protector: Canary modified");
@@ -65,6 +66,7 @@ void panic(const char* why)
   __builtin_unreachable();
 }
 
+__attribute__((used))
 void* memset(char* dest, int ch, size_t size)
 {
   for (size_t i = 0; i < size; i++)