Guide to Advanced Programming in C

Table of Contents

1 Integer Overflows and Promotions

2 Memory Allocation and Management

Many operating systems provide interface to control access over memory regions to protect memory against unintended read/write operations such as Posix mprotect . These mechanisms usually apply to whole memory pages. (mprotect以page为单位) 给出了每个平台默认stack大小以及修改方法

Stack Overflow Problems
This file gives some hints on addressing this problem on different platforms.

Under Unix-like systems, programs may throw a "Segmentation Fault"
error.  This can be due to stack overflow, especially from recursive
function calls or huge data sets.  In our demo program "Pi"
(see "$(CORE_PATH)/progs/pi"), we compute Pi to any number of desired
bits or digits.  Here are some test results on when stack overflows
will occur on different platforms, using their default stack sizes.

	platform	default size	# bits	# digits
	SunOS/Solaris	8172K bytes	<=39875	<=12003	(Shared Version)
	Linux 		8172K bytes	<=62407	<=18786
	Windows		1024K bytes	<=10581	<=3185	(Release Version)
	cygwin		2048K bytes	<=3630	<=1092

If we now change their stack size to their maximum, our Pi program can
compute more bits.

	platform	stack size	# bits		# digits
	SunOS/Solaris	unlimited	>=100,000	30102
	Linux		8172K bytes	<=33,219,282	<=10,000,000(?)
	Windows		32768K bytes	<=343077	<=12041

How to change the default stack size on different platforms:
In general, under Unix-like platforms, the stack size is controlled
by environment variable, not the program itself.
So you cannot pass any flags to the
compilers, like gcc, to setup stack size.  Under Windows platforms, the
stack size information is contained in the executable files.  It can be set
during compilation in Visual C++, but this is not available in gcc.
Alternatively, Microsoft provides a program "editbin.exe" which can change the
executable files directly.  Here are more details:

	> limit			 # shows the current stack size
	> unlimit		 # changes the stack size to unlimited
	> setenv STACKSIZE 32768 # limits the stack size to 32M bytes

	> ulimit -a		# shows the current stack size
	> ulimit -s 32768	# sets the stack size to 32M bytes

Windows (during compilation):
	1. Select "Project->Setting".
	2. Select "Link" page.
	3. Select "Category" to "Output".
	4. Type your preferred stack size in "Reserve:" field under "Stack
	   allocations". eg, 32768 in decimal or 0x20000 in hexadecimal.

Windows (to modify the executable file):
There are two programs included in Microsoft Visual Studio, "dumpbin.exe"
 and "editbin.exe".  Run "dumpbin /headers executable_file", and you can see
the "size of stack reserve" information in "optional header values".  Run
"editbin /STACK:size" to change the default stack size.

3 Pointers and Arrays

4 Interpositioning

__attribute__ ((visibility (<value>))) 可以用来控制符号可见域,其中value可以指定为

  • "default" # 对其他单元可见
  • "hidden" # 仅对本单元可见


5 Explicit Inlining

inline __attribute__((always _inline)) 可以强制inline.

6 Vector Extensions


  • x86: x86intrin.h
  • MMX: mmintrin.h
  • SSE: xmmintrin.h
  • SSE2: emmintrin.h
  • SSE3: mm3dnow.h
  • 3dnow: tmmintrin.h
  • AVX: immintrin.h


/* SSE2 */
typedef double __v2df __attribute__ ((__vector_size__ (16)));
typedef long long __v2di __attribute__ ((__vector_size__ (16)));
typedef int __v4si __attribute__ ((__vector_size__ (16)));
typedef short __v8hi __attribute__ ((__vector_size__ (16)));
typedef char __v16qi __attribute__ ((__vector_size__ (16)));