5. 请问如何在C++中使用SIMD？

请问如何在C++中使用SIMD？

  • 老

    使用sw5CC编译使用了带SIMD的程序

    #ifdef __cplusplus
    extern "C" {
    #endif
    #include <simd.h>
    #ifdef __cplusplus
    }
    #endif

    int main()
    {
    doublev4 a;
    double *p = (double *)&a;
    p[0] = 1.0;
    p[1] = 2.0;
    p[2] = 2.5;
    p[3] = 3.0;
    simd_print_doublev4(a);
    doublev4 b = -1.0;
    simd_print_doublev4(b);
    simd_print_doublev4(simd_vmuld(a, b));
    return 0;
    }
    这样编译会报错：
    simd.cpp: In function 'int main()':
    simd.cpp:21: error: cannot convert 'double' to 'double vector' in initialization
    simd.cpp:24: error: '__builtin_sw64_dlum' was not declared in this scope
    请问如何在C++中使用SIMD？

    0
    P
     1 条回复
  • P

    @老泽征尔 在 请问如何在C++中使用SIMD？ 中说：

    simd.cpp:24: error: '__builtin_sw64_dlum' was not declared in this scope

    目测是因为c++里面类型检查更为严格，再加上神威自己的c++编译器识别不了神威的simd builtin。
    嵌汇编就好了。。。T_T。

    #ifdef __cplusplus
extern "C" {
#endif
#include <simd.h>
#ifdef __cplusplus
}
#endif
extern doublev4 __builtin_sw64_dlum(doublev4 a, doublev4 b);
int main()
{
  doublev4 a;
  double *p = (double *)&a;
  p[0] = 1.0;
  p[1] = 2.0;
  p[2] = 2.5;
  p[3] = 3.0;
  simd_print_doublev4(a);
  doublev4 b = simd_set_doublev4(-1.0, -1.0, -1.0, -1.0);
  doublev4 c;
  asm ("vmuld %1, %2, %0\n\t": "=f"(c) : "f"(a), "f"(b));
  simd_print_doublev4(b);
  simd_print_doublev4(c);
  return 0;
}
    0
  • 老

    感谢您的回复

    如何在sw5CC编译的函数中使用向量作为返回值呢？
    例如函数

    static inline doublev4 myset1(double a, double b, double c, double d)
{
	doublev4 r;
	r = simd_set_doublev4(a, b, c, d);
	return r;
}

    编译就会报错

    [cpcXXX@psn004 Athread]$ sw5CC -host -msimd simd.cpp 

### Assertion failure at line 5510 of ../../wgen/wgen_decl.cxx:
### Compiler Error during Writing WHIRL file phase:
### WGEN_Handle_Named_Return_Value: nrv type not in mem
CC INTERNAL ERROR: /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/wgen42 returned non-zero status 1

    @popo

    另，在编译修改后的Gromacs中的pme-spread.cpp文件会报错

    Signal: Segmentation fault in Code_Expansion phase.
Error: Signal Segmentation fault in phase Code_Expansion -- processing aborted
*** Internal stack backtrace:
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be.so(+0x32a1f2) [0x2b88dafa11f2]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be.so(+0x32a280) [0x2b88dafa1280]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be.so(+0x32b963) [0x2b88dafa2963]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be.so(+0x32ba57) [0x2b88dafa2a57]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be.so(ErrMsgLine+0xce) [0x2b88dafa2c26]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be.so(+0x32995b) [0x2b88dafa095b]
    /lib64/libc.so.6() [0x306ec326a0]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(_Z32REGISTER_CLASS_OP_Update_MappingP2op+0x10e) [0x2b88dbae334f]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(+0x2b8218) [0x2b88dbb3e218]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(_Z13BB_Append_OpsP2bbP3ops+0x7b) [0x2b88dbb3ec9c]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(+0x260d09) [0x2b88dbae6d09]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(+0x26202a) [0x2b88dbae802a]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(+0x266b09) [0x2b88dbaecb09]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(+0x26c086) [0x2b88dbaf2086]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(+0x26c8a7) [0x2b88dbaf28a7]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(+0x26c5eb) [0x2b88dbaf25eb]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(_Z20Convert_WHIRL_To_OPsP2WN+0x2dc) [0x2b88dbaf2baa]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/cg.so(CG_Generate_Code+0x1dc) [0x2b88dba41415]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be() [0x40dff2]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be() [0x40e862]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be() [0x40f599]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be(main+0x6a8) [0x4100f9]
    /lib64/libc.so.6(__libc_start_main+0xfd) [0x306ec1ed5d]
    /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be() [0x40b9e9]
CC INTERNAL ERROR: /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be died due to signal 4
CC ERROR: core dumped

    或者

    ### Assertion failure at line 421 of ../../be/cg/alpha/exp_loadstore.cxx:
### Compiler Error in file /home/export/online1/cpc124/sunjun/projects/final/src/gromacs/ewald/pme-spread.cpp during Code_Expansion phase:
### NYI: Pick_Load_Instruction mtype
cc INTERNAL ERROR: /usr/sw-mpp/swcc/lib/gcc-lib/sw_64-swcc-linux/5.421-sw-500/be returned non-zero status 1

    其余cpp文件编译没问题，就这个文件有问题

    0
  • P

    @老泽征尔 doublev4这个类型sw5CC应该没有定义，你需要自己定义一个doublev4类型

    0
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