e5e7f488e2
{
struct st {
int aa:16;
int bb:16;
} s;
s.aa = 1;
s.bb = 2;
return 0;
}
objdump -d:
elf64-x86-64
Disassembly of section .text:
0000000000000000 <main>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: 48 81 ec 10 00 00 00 sub $0x10,%rsp
b: b8 01 00 00 00 mov $0x1,%eax
10: 48 89 c1 mov %rax,%rcx
13: 81 e1 ff ff 00 00 and $0xffff,%ecx
19: 8b 55 fc mov -0x4(%rbp),%edx
1c: 81 e2 00 00 ff ff and $0xffff0000,%edx
22: 09 d1 or %edx,%ecx
24: 89 4d fc mov %ecx,-0x4(%rbp)
27: b8 02 00 00 00 mov $0x2,%eax
2c: 48 89 c1 mov %rax,%rcx
2f: 81 e1 ff ff 00 00 and $0xffff,%ecx
35: c1 e1 10 shl $0x10,%ecx
38: 8b 55 fc mov -0x4(%rbp),%edx
3b: 81 e2 ff ff 00 00 and $0xffff,%edx
41: 09 d1 or %edx,%ecx
43: 89 4d fc mov %ecx,-0x4(%rbp)
46: b8 00 00 00 00 mov $0x0,%eax
4b: e9 00 00 00 00 jmpq 50 <main+0x50>
50: c9 leaveq
51: c3 retq
After the patch
Disassembly of section .text:
0000000000000000 <main>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: 48 81 ec 10 00 00 00 sub $0x10,%rsp
b: 8b 45 fc mov -0x4(%rbp),%eax
e: 81 e0 00 00 ff ff and $0xffff0000,%eax
14: 83 c8 01 or $0x1,%eax
17: 89 45 fc mov %eax,-0x4(%rbp)
1a: 8b 45 fc mov -0x4(%rbp),%eax
1d: 81 e0 ff ff 00 00 and $0xffff,%eax
23: 81 c8 00 00 02 00 or $0x20000,%eax
29: 89 45 fc mov %eax,-0x4(%rbp)
2c: b8 00 00 00 00 mov $0x0,%eax
31: e9 00 00 00 00 jmpq 36 <main+0x36>
36: c9 leaveq
37: c3 retq
Tiny C Compiler - C Scripting Everywhere - The Smallest ANSI C compiler ----------------------------------------------------------------------- Features: -------- - SMALL! You can compile and execute C code everywhere, for example on rescue disks. - FAST! tcc generates optimized x86 code. No byte code overhead. Compile, assemble and link about 7 times faster than 'gcc -O0'. - UNLIMITED! Any C dynamic library can be used directly. TCC is heading torward full ISOC99 compliance. TCC can of course compile itself. - SAFE! tcc includes an optional memory and bound checker. Bound checked code can be mixed freely with standard code. - Compile and execute C source directly. No linking or assembly necessary. Full C preprocessor included. - C script supported : just add '#!/usr/local/bin/tcc -run' at the first line of your C source, and execute it directly from the command line. Documentation: ------------- 1) Installation on a i386/x86_64/arm Linux/OSX/FreeBSD host (for Windows read tcc-win32.txt) Note: For OSX and FreeBSD, gmake should be used instead of make. ./configure make make test make install Alternatively, out-of-tree builds are supported: you may use different directories to hold build objects, kept separate from your source tree: mkdir _build cd _build ../configure make make test make install Texi2html must be installed to compile the doc. By default, tcc is installed in /usr/local/bin. ./configure --help shows configuration options. 2) Introduction We assume here that you know ANSI C. Look at the example ex1.c to know what the programs look like. The include file <tcclib.h> can be used if you want a small basic libc include support (especially useful for floppy disks). Of course, you can also use standard headers, although they are slower to compile. You can begin your C script with '#!/usr/local/bin/tcc -run' on the first line and set its execute bits (chmod a+x your_script). Then, you can launch the C code as a shell or perl script :-) The command line arguments are put in 'argc' and 'argv' of the main functions, as in ANSI C. 3) Examples ex1.c: simplest example (hello world). Can also be launched directly as a script: './ex1.c'. ex2.c: more complicated example: find a number with the four operations given a list of numbers (benchmark). ex3.c: compute fibonacci numbers (benchmark). ex4.c: more complicated: X11 program. Very complicated test in fact because standard headers are being used ! As for ex1.c, can also be launched directly as a script: './ex4.c'. ex5.c: 'hello world' with standard glibc headers. tcc.c: TCC can of course compile itself. Used to check the code generator. tcctest.c: auto test for TCC which tests many subtle possible bugs. Used when doing 'make test'. 4) Full Documentation Please read tcc-doc.html to have all the features of TCC. Additional information is available for the Windows port in tcc-win32.txt. License: ------- TCC is distributed under the GNU Lesser General Public License (see COPYING file). Fabrice Bellard.