Build: add optimization flags.

Compile with the standard -O2 optimization flag and enable Link Time
Optimizations. Fix a uninitialized variable in RawLinkedList implementation.

Testing done: make kernel
qemu -kernel out/kernel/Kernel/Kernel.bin -m 512

build/config.mk

@@ -24,13 +24,17 @@ BUILD_TEST := $(BUILD_ROOT)/build-tests.mk
 BUILD_EXECUTABLE := $(BUILD_ROOT)/build-executable.mk
 
 # Default build flags
-DEFAULT_FLAGS := -m32 -Wall -Wextra -Werror -g -gstabs -pipe
+DEFAULT_FLAGS := -m32 -Wall -Wextra -Werror -g -gstabs -pipe -O2
 DEFAULT_CFLAGS := $(DEFAULT_FLAGS) -std=c99
 DEFAULT_CPPFLAGS := $(DEFAULT_FLAGS)
 DEFAULT_ASFLAGS := $(DEFAULT_FLAGS)
 DEFAULT_LDFLAGS := -melf_i386
 DEFAULT_ARFLAGS := rcs
 
+# Link Time Optimization
+DEFAULT_FLAGS += -flto -flto-compression-level=9 -fuse-linker-plugin
+DEFAULT_LDFLAGS += -flto
+
 # Kernel build flags
 KERNEL_INCLUDES := kernel/ kernel/CUtils/
 KERNEL_CFLAGS := -nostdinc -fno-stack-protector

kernel/Utils/RawLinkedList.h

@@ -176,11 +176,11 @@ void RawLinkedList<T>::removeAt(unsigned i)
         assert(pos == i-1);
         d = n->next;
         n->next = d->next;
-    }
 
-    /* Handle the last element case */
-    if (mLast == d) {
-        mLast = n;
+        /* Handle the last element case */
+        if (mLast == d) {
+           mLast = n;
+        }
     }
 
     /* Handle when the list is empty */