Some Problems about gcc 4.8.2 on cygwin

Some Problems about gcc 4.8.2 on cygwin

[rexdf Rexdf]

1.the following code:

#include <unistd.h>
#include <curses.h>
int main() {
   initscr();
   move(0, 0);
   addstr("hello, world\n");
   refresh();
   sleep(5);
   endwin();
   return 0;
}

The following is my shell command:

$ pkg-config --libs --cflags ncurses
-I/usr/include/ncurses  -lncurses

$ gcc $(pkg-config --libs --cflags ncurses) curses_test.c -o curses_test
/tmp/cc74H73T.o:curses_test.c:(.text+0xf): undefined reference to `initscr'
/tmp/cc74H73T.o:curses_test.c:(.text+0x14): undefined reference to
`ncwrap_stdscr'
/tmp/cc74H73T.o:curses_test.c:(.text+0x2c): undefined reference to `wmove'
/tmp/cc74H73T.o:curses_test.c:(.text+0x31): undefined reference to
`ncwrap_stdscr'
/tmp/cc74H73T.o:curses_test.c:(.text+0x49): undefined reference to `waddnstr'
/tmp/cc74H73T.o:curses_test.c:(.text+0x4e): undefined reference to
`ncwrap_stdscr'
/tmp/cc74H73T.o:curses_test.c:(.text+0x56): undefined reference to `wrefresh'
/tmp/cc74H73T.o:curses_test.c:(.text+0x67): undefined reference to `endwin'
/usr/lib/gcc/i686-pc-cygwin/4.8.2/../../../../i686-pc-cygwin/bin/ld:
/tmp/cc74H73T.o: bad reloc address 0x20 in section `.eh_frame'
/usr/lib/gcc/i686-pc-cygwin/4.8.2/../../../../i686-pc-cygwin/bin/ld:
final link failed: Invalid operation
collect2: error: ld returned 1 exit status

$ gcc curses_test.c $(pkg-config --libs --cflags ncurses) -o curses_test

$ ./curses_test.exe


Do I have to put the source file before `-I/usr/include/ncurses
-lncurses`? And why?


2.It's about OpenMP
openmp_1.cpp
#include <iostream>
#include <time.h>
void test()
{
    int a = 0;
    for (int i=0;i<100000000;i++)
        a++;
}
int main()
{
    clock_t t1 = clock();
    for (int i=0;i<8;i++)
        test();
    clock_t t2 = clock();
    std::cout<<"time: "<<t2-t1<<std::endl;
}

openmp_2.cpp
#include <iostream>
#include <time.h>
void test()
{
    int a = 0;
    for (int i=0;i<100000000;i++)
        a++;
}
int main()
{
    clock_t t1 = clock();
    #pragma omp parallel for
    for (int i=0;i<8;i++)
        test();
    clock_t t2 = clock();
    std::cout<<"time: "<<t2-t1<<std::endl;
}

On cygwin
g++ openmp_1.cpp -o openmp_1.exe
g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
time 1937
time 2297

On MingW-g++ 4.8.1
g++ openmp_1.cpp -o openmp_1.exe
g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
time 1975
time 492

On Visual Studio 2013
Openmp_2.cpp Project
C/C++ --> Language --> Open MP Support yes(/openmp)
time 1849
time 321

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Re: Some Problems about gcc 4.8.2 on cygwin

[Marco Atzeri]

On 14/03/2014 13:42, rexdf Rexdf wrote:
> 1.the following code:
>
> #include <unistd.h>
> #include <curses.h>
> int main() {
>     initscr();
>     move(0, 0);
>     addstr("hello, world\n");
>     refresh();
>     sleep(5);
>     endwin();
>     return 0;
> }
>
> The following is my shell command:
>
> $ pkg-config --libs --cflags ncurses
> -I/usr/include/ncurses  -lncurses
>
> $ gcc $(pkg-config --libs --cflags ncurses) curses_test.c -o curses_test

try this way

gcc  curses_test.c -o curses_test $(pkg-config --libs --cflags ncurses)


> 2.It's about OpenMP
> openmp_1.cpp
> #include <iostream>
> #include <time.h>
> void test()
> {
>      int a = 0;
>      for (int i=0;i<100000000;i++)
>          a++;
> }
> int main()
> {
>      clock_t t1 = clock();
>      for (int i=0;i<8;i++)
>          test();
>      clock_t t2 = clock();
>      std::cout<<"time: "<<t2-t1<<std::endl;
> }
>
> openmp_2.cpp
> #include <iostream>
> #include <time.h>
> void test()
> {
>      int a = 0;
>      for (int i=0;i<100000000;i++)
>          a++;
> }
> int main()
> {
>      clock_t t1 = clock();
>      #pragma omp parallel for
>      for (int i=0;i<8;i++)
>          test();
>      clock_t t2 = clock();
>      std::cout<<"time: "<<t2-t1<<std::endl;
> }
>
> On cygwin
> g++ openmp_1.cpp -o openmp_1.exe
> g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
> time 1937
> time 2297
>
> On MingW-g++ 4.8.1
> g++ openmp_1.cpp -o openmp_1.exe
> g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
> time 1975
> time 492
>
> On Visual Studio 2013
> Openmp_2.cpp Project
> C/C++ --> Language --> Open MP Support yes(/openmp)
> time 1849
> time 321

and the question is ?

Marco

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Re: Some Problems about gcc 4.8.2 on cygwin

[Tim Prince]

On 3/14/2014 8:42 AM, rexdf Rexdf wrote: 2.It's about OpenMP
<elided stuff which doesn't quote legibly>
Is there a cygwin related question here?  Questions on OpenMP and 
clock() might be tolerated on gcc-help.
Advice on how to make meaningful benchmarks is definitely off topic.

With cygwin g++ 4.9 at -O or -O3 on win8.1 I get
time: 0
as evidently the compiler can shortcut your test loop (is that what you 
wished?).

For the -O0 -fopenmp build,
time: 2484    (1 thread)
time: 2547    (2 threads)
time: 2828    (3 t)
time: 3187    (4 t)
Much as would be expected, as you are asking for the total time spent 
among all threads (usual interpretation of clock()).
The bash time command shows real time decreasing with number of threads 
(close to total clock time divided by number of threads). OpenMP 
provides the function omp_get_wtime() for performance measurement 
(possibly a wrapper for gettimeofday()).
The cygwin library evidently doesn't treat clock() as equivalent to 
omp_get_wtime().  Speculation on how you could find a non-cygwin library 
which treats them as equivalent is probably off topic here.
Anyway, I think your problem is not with the cygwin gcc, unless you are 
looking for the more aggressive optimization of version 4.9.

-- 
Tim Prince


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Re: Some Problems about gcc 4.8.2 on cygwin

[rexdf Rexdf]

If you use -O3 or -O2, then the loop is optimed to nothing. Because
the a++ never is used.

My question is :
1. On archlinux gcc 4.8.2, `gcc curses_test.c $(pkg-config --libs
--cflags ncurses) -o curses_test` and `gcc $(pkg-config --libs
--cflags ncurses) curses_test.c -o curses_test` works.
On cygwin it doesn't work, why?

2. what is wrong in openmp on cygwin? How can I fix it?

2014-03-14 20:42 GMT+08:00 rexdf Rexdf <weiyong.mao@gmail.com>:
> 1.the following code:
>
> #include <unistd.h>
> #include <curses.h>
> int main() {
>    initscr();
>    move(0, 0);
>    addstr("hello, world\n");
>    refresh();
>    sleep(5);
>    endwin();
>    return 0;
> }
>
> The following is my shell command:
>
> $ pkg-config --libs --cflags ncurses
> -I/usr/include/ncurses  -lncurses
>
> $ gcc $(pkg-config --libs --cflags ncurses) curses_test.c -o curses_test
> /tmp/cc74H73T.o:curses_test.c:(.text+0xf): undefined reference to `initscr'
> /tmp/cc74H73T.o:curses_test.c:(.text+0x14): undefined reference to
> `ncwrap_stdscr'
> /tmp/cc74H73T.o:curses_test.c:(.text+0x2c): undefined reference to `wmove'
> /tmp/cc74H73T.o:curses_test.c:(.text+0x31): undefined reference to
> `ncwrap_stdscr'
> /tmp/cc74H73T.o:curses_test.c:(.text+0x49): undefined reference to `waddnstr'
> /tmp/cc74H73T.o:curses_test.c:(.text+0x4e): undefined reference to
> `ncwrap_stdscr'
> /tmp/cc74H73T.o:curses_test.c:(.text+0x56): undefined reference to `wrefresh'
> /tmp/cc74H73T.o:curses_test.c:(.text+0x67): undefined reference to `endwin'
> /usr/lib/gcc/i686-pc-cygwin/4.8.2/../../../../i686-pc-cygwin/bin/ld:
> /tmp/cc74H73T.o: bad reloc address 0x20 in section `.eh_frame'
> /usr/lib/gcc/i686-pc-cygwin/4.8.2/../../../../i686-pc-cygwin/bin/ld:
> final link failed: Invalid operation
> collect2: error: ld returned 1 exit status
>
> $ gcc curses_test.c $(pkg-config --libs --cflags ncurses) -o curses_test
>
> $ ./curses_test.exe
>
>
> Do I have to put the source file before `-I/usr/include/ncurses
> -lncurses`? And why?
>
>
> 2.It's about OpenMP
> openmp_1.cpp
> #include <iostream>
> #include <time.h>
> void test()
> {
>     int a = 0;
>     for (int i=0;i<100000000;i++)
>         a++;
> }
> int main()
> {
>     clock_t t1 = clock();
>     for (int i=0;i<8;i++)
>         test();
>     clock_t t2 = clock();
>     std::cout<<"time: "<<t2-t1<<std::endl;
> }
>
> openmp_2.cpp
> #include <iostream>
> #include <time.h>
> void test()
> {
>     int a = 0;
>     for (int i=0;i<100000000;i++)
>         a++;
> }
> int main()
> {
>     clock_t t1 = clock();
>     #pragma omp parallel for
>     for (int i=0;i<8;i++)
>         test();
>     clock_t t2 = clock();
>     std::cout<<"time: "<<t2-t1<<std::endl;
> }
>
> On cygwin
> g++ openmp_1.cpp -o openmp_1.exe
> g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
> time 1937
> time 2297
>
> On MingW-g++ 4.8.1
> g++ openmp_1.cpp -o openmp_1.exe
> g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
> time 1975
> time 492
>
> On Visual Studio 2013
> Openmp_2.cpp Project
> C/C++ --> Language --> Open MP Support yes(/openmp)
> time 1849
> time 321

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Re: Some Problems about gcc 4.8.2 on cygwin

[Marco Atzeri]

On 14/03/2014 15:00, rexdf Rexdf wrote:

please read
    http://en.wikipedia.org/wiki/Posting_style
in this mailing list we use "Bottom-posting" and "Trimming"

> My question is :
> 1. On archlinux gcc 4.8.2, `gcc curses_test.c $(pkg-config --libs
> --cflags ncurses) -o curses_test` and `gcc $(pkg-config --libs
> --cflags ncurses) curses_test.c -o curses_test` works.
> On cygwin it doesn't work, why?
>

because Windows works differently and the order matters.

> 2. what is wrong in openmp on cygwin? How can I fix it?

I doubt something is wrong, likely you have wrong expectation


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