- clang: C语言编译器，类似于gcc
- clang++: C++编译器，类似于g++。clang++只是clang的一个别名。
- lld: 链接器，类似于ld。但是默认不用它，默认用vc的link.exe。
- clang-format：按照固定的规范格式化C/C++代码，非常智能。文档请见：http://clang.llvm.org/docs/ClangFormat.html
- clang-modernize：把按照C++98标准写的代码，转成C++11标准的。文档请见：http://clang.llvm.org/extra/ModernizerUsage.html
- llvm-as - LLVM 汇编器
- llvm-dis - LLVM 反汇编器
- opt - LLVM 优化器
- llc - LLVM 静态编译器
- lli - LLVM的字节码执行器（某些平台下支持JIT）
- llvm-link - LLVM的字节码链接器
- llvm-ar - LLVM的静态库打包器，类似unix的ar。
- llvm-nm - 类似于unix的nm
Sanitizer
clang有一个王牌功能是sanitizer。它包含三种：AddressSanitizer、MemorySanitizer、ThreadSanitizer。AddressSanitizer和MemorySanitizer最初是google开发的，用于运行时检测C/C++程序中的内存错误。在编译的时候加上-fsanitizer参数，编译器就会在生成的代码中插入一些运行时检查。比如你可以拿下面的这段代码试下：
#include <stdio.h> #include <string.h> int main(int argc,char* argv[]){ char buf[4]; strcpy(buf,argv[1]); printf("%s\n",buf); return 0; }它把命令行的第一个参数复制到一个临时的缓存区中，然后打印出来。
这段代码有两个bug：
- 在访问argv的时候可能会越界。（用户执行时没有加任何参数）
- buf不够长，写入时可能会越界，这将会造成严重的安全漏洞。
来，编译试下：
C:>clang++ -fsanitize=address -o t.exe badcode.cpp -g3 -DDEBUG -D_DEBUG
然后运行：
C:>t 3
3C:>t 355
355C:>t 3554664
=================================================================
==4044==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x0024fd44 at
pc 0x1274038 bp 0xdeadbeef sp 0x24fbf0
WRITE of size 8 at 0x0024fd44 thread T0
#0 0x127404c wrap_strcpy c:\users\cm\documents\os\llvm-3.4\projects\compile
r-rt\lib\asan\asan_interceptors.cc:490
#1 0x12612a7 main+0x0x000002a7
#2 0x1278212 __tmainCRTStartup f:\dd\vctools\crt\crtw32\startup\crt0.c:255
#3 0x772d3369 BaseThreadInitThunk+0x0x00000011
#4 0x77ba9f71 RtlInitializeExceptionChain+0x0x00000062
#5 0x77ba9f44 RtlInitializeExceptionChain+0x0x00000035Address 0x0024fd44 is located in stack of thread T0 at offset 228 in frame
#0 0x126100f main+0x0x0000000fThis frame has 4 object(s):
[32, 36) ”
[96, 100) ”
[160, 164) ”
[224, 228) ‘buf’ <== Memory access at offset 228 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind
mechanism or swapcontext
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow ??:0 ??
Shadow bytes around the buggy address:
0x20049f50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x20049f60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x20049f70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x20049f80: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
0x20049f90: 04 f4 f4 f4 f2 f2 f2 f2 04 f4 f4 f4 f2 f2 f2 f2
=>0x20049fa0: 04 f4 f4 f4 f2 f2 f2 f2[04]f4 f4 f4 f3 f3 f3 f3
0x20049fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x20049fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x20049fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x20049fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x20049ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
ASan internal: fe
==4044==ABORTING它会提前把错误检测出来，并终止程序。
但是memory sanitizer目前在windows下还不能用。