gcc优化和如何使用-O2编译内核...

study/problem/build/no_optimize/1-dead_code.c

@@ -0,0 +1,41 @@
+// http://blog.csdn.net/liyuanbhu/article/details/42470577
+/*
+	mm/memory.o: In function `insert_pfn':
+	/home/gatieme/Work/Kernel/linux/linux/mm/memory.c:1813: undefined reference to `pte_mkdevmap'
+*/
+#include <stdlib.h>
+#include <stdio.h>
+
+//#define CONFIG_TARGET_X86_64
+
+#ifdef CONFIG_TARGET_X86_64
+static void A( )
+{
+	printf("A\n");
+}
+#else
+void A( ) __attribute__ ((weak));;
+#endif
+
+static void B( )
+{
+	printf("B\n");
+}
+
+
+static int xx( )
+{
+#ifdef CONFIG_TARGET_X86_64
+  return 1;
+#else
+  return 0;
+#endif
+}
+
+int main(void)
+{
+  if (xx( ))   /* define CONFIG_TARGET_X86_64 */
+    A( );
+  else
+    B( );
+}

study/problem/build/no_optimize/1.c

@@ -0,0 +1,34 @@
+/*************************************************************************
+    > File Name: 1.c
+    > Author: GatieMe
+    > Mail: gatieme@163.com
+    > Created Time: Sun 26 Nov 2017 11:47:59 AM CST
+ ************************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+
+static void A( );
+
+
+#ifdef CONFIG_TEST_MACRO
+static void A( )
+{
+	printf("A\n");
+}
+#endif
+
+static void xx( )
+{
+	A( );
+}
+
+int main(int argc, char *argv[])
+{
+	xx( );
+
+	return EXIT_SUCCESS;
+}
+
+

study/problem/build/no_optimize/2-dead_code.c

@@ -0,0 +1,44 @@
+// http://blog.csdn.net/liyuanbhu/article/details/42470577
+/*
+	mm/memory.o: In function `insert_pfn':
+	/home/gatieme/Work/Kernel/linux/linux/mm/memory.c:1813: undefined reference to `pte_mkdevmap'
+*/
+#include <stdlib.h>
+#include <stdio.h>
+
+//#define CONFIG_TARGET_X86_64
+
+#ifdef CONFIG_TARGET_X86_64
+static int xx( )
+{
+	return 1;
+}
+
+static void A( )
+{
+	printf("A\n");
+}
+#else
+static int xx( )
+{
+	return 0;
+}
+
+//void A( ) __attribute__ ((weak));;
+void A( );// __attribute__ ((weak));;
+#endif
+
+static void B( )
+{
+	printf("B\n");
+}
+
+
+
+int main(void)
+{
+  if (xx( ))   /* define CONFIG_TARGET_X86_64 */
+    A( );
+  else
+    B( );
+}

study/problem/build/no_optimize/3-dead_code.c

@@ -0,0 +1,48 @@
+// http://blog.csdn.net/liyuanbhu/article/details/42470577
+/*
+	mm/memory.o: In function `insert_pfn':
+	/home/gatieme/Work/Kernel/linux/linux/mm/memory.c:1813: undefined reference to `pte_mkdevmap'
+*/
+#include <stdlib.h>
+#include <stdio.h>
+
+//#define CONFIG_TARGET_X86_64
+
+#ifdef CONFIG_TARGET_X86_64
+static int xx( )
+{
+	return 1;
+}
+
+void A( )
+{
+	printf("A\n");
+}
+#else
+static int xx( )
+{
+	return 0;
+}
+
+//void A( ) __attribute__ ((weak));;
+void A( );// __attribute__ ((weak));;
+#endif
+
+static void B( )
+{
+	printf("B\n");
+}
+
+static void AA( )
+{
+	A( );
+}
+
+int main(void)
+{
+  if (xx( ))   /* define CONFIG_TARGET_X86_64 */
+    A( );
+  else
+    B( );
+  AA( );
+}

study/problem/build/no_optimize/Makefile

@@ -0,0 +1,54 @@
+#
+#http://blog.sina.com.cn/s/blog_694f2ae70101amh6.html
+#
+target=test
+
+CURRENT_BIN_DIR=ptrace_bug
+INSTALL_ROOT_DIR=~/Work/Kernel/runninglinuxkernel/filesystem
+INSTALL_HOME_DIR=home/chengjian
+
+ifeq ($(ARCH), arm64)
+	CROSS_COMPILE=/opt/arm/toolschain/linaro/gcc-linaro-7.1.1-2017.08-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu-
+	ARCH_FILE_DIR=_install_arm64
+else ifeq ($(ARCH), arm32)
+	CROSS_COMPILE=arm-linux-gnueabi-
+	ARCH_FILE_DIR=_install_arm32
+else	# ifeq ($(ARCH), x86_64)
+	ARCH_FILE_DIR=_install_x86
+endif
+
+INSTALL_BIN_DIR=$(INSTALL_ROOT_DIR)/$(ARCH_FILE_DIR)/$(INSTALL_HOME_DIR)/ #$(CURRENT_BIN_DIR)
+
+CFLAGS+= -finline-small-functions  		\
+	 -findirect-inlining       		\
+	 -fpartial-inlining 			\
+         -finline-functions			\
+	 -finline-functions-called-once
+
+CC=${CROSS_COMPILE}gcc
+AS=${CROSS_COMPILE}as
+LD=${CROSS_COMPILE}ld
+LDFLAGS+=-static
+
+
+all : $(target)
+
+test:test.c
+	$(CC) $^ -o $@ $(LDFLAGS) $(CFLAGS)
+	@echo "ptrace singlestep..."
+
+%.o : %.c
+	$(CC) -c $^ -o $@  $(CFLAGS) $(DEFINES)
+
+%.o	: %.cpp
+	$(CXX) -c $^ -o $@  $(CFLAGS) $(DEFINES)
+
+clean :
+	rm -rf *.o
+	rm -rf $(target)
+
+install	:
+	mkdir -p $(CURRENT_BIN_DIR)
+	cp $(target) $(CURRENT_BIN_DIR)
+	#echo $(INSTALL_BIN_DIR)
+	cp -rf $(CURRENT_BIN_DIR) $(INSTALL_BIN_DIR) 

study/problem/build/no_optimize/test.c

@@ -0,0 +1,45 @@
+// http://blog.csdn.net/liyuanbhu/article/details/42470577
+/*
+	mm/memory.o: In function `insert_pfn':
+	/home/gatieme/Work/Kernel/linux/linux/mm/memory.c:1813: undefined reference to `pte_mkdevmap'
+*/
+#include <stdlib.h>
+#include <stdio.h>
+
+//#define CONFIG_TARGET_X86_64
+
+#ifdef CONFIG_TARGET_X86_64
+static void A( )
+{
+	printf("A\n");
+}
+#else
+static void A( )
+{
+}
+#endif
+
+static void B( )
+{
+	printf("B\n");
+}
+
+
+inline int xx( )
+//static inline int xx( ) /* right */
+//int xx( ) /* right */
+{
+#ifdef CONFIG_TARGET_X86_64
+  return 1;
+#else
+  return 0;
+#endif
+}
+
+int main(void)
+{
+	if (xx( ))
+		A( );
+	else
+		B( );
+}