CODEWITHSUNDEEP
c
elemein
elemein

Reputation: 207

SIMD programming: "mode 'V4SF' applied to inappropriate type" error

I am trying to use SIMD instructions in my C program. I am using CodeBlocks to write in.

I tried following this tutorial: https://www.kernel.org/pub/linux/kernel/people/geoff/cell/ps3-linux-docs/CellProgrammingTutorial/BasicsOfSIMDProgramming.html

I am trying to do both integer and floating point SIMD addition, subtraction, etc.

However, the code explained in the page does not work in CodeBlocks/C. How do I use SIMD here?

#include <stdio.h>
typedef int v4sf __attribute__ ((mode(V4SF))); // vector of four single floats

union f4vector
{
  v4sf v;
  float f[4];
};
int main()
{
  union f4vector a, b, c;

  a.f[0] = 1; a.f[1] = 2; a.f[2] = 3; a.f[3] = 4;
  b.f[0] = 5; b.f[1] = 6; b.f[2] = 7; b.f[3] = 8;

  c.v = a.v + b.v;

  printf("%f, %f, %f, %f\n", c.f[0], c.f[1], c.f[2], c.f[3]);
}

C:\Things\New Text Document.c|2|warning: specifying vector types with __attribute__ ((mode)) is deprecated [-Wattributes]|
C:\Things\New Text Document.c|2|warning: use __attribute__ ((vector_size)) instead [-Wattributes]|
C:\Things\New Text Document.c|2|error: mode 'V4SF' applied to inappropriate type|
||=== Build failed: 1 error(s), 2 warning(s) (0 minute(s), 0 second(s)) ===|

Upvotes: 0

Views: 807

Answers (3)

Harvee
Harvee

Reputation: 11

the tuition has something wrong that the typedef origin date type should be the float.

For a compile through example is as follow

#include <stdio.h>
typedef float v4sf __attribute__((vector_size(16)));

union f4vector
{
    v4sf v;
    float f[4];
};

int main()
{
    union f4vector a, b, c;

    a.f[0] = 1; a.f[1] = 2; a.f[2] = 3; a.f[3] = 4;
    b.f[0] = 5; b.f[1] = 6; b.f[2] = 7; b.f[3] = 8;

    c.v = a.v + b.v;

    printf("%f, %f, %f, %f\n", c.f[0], c.f[1], c.f[2], c.f[3]);
}

Upvotes: 1

Jason
Jason

Reputation: 3917

You need to make sure your CPU supports the vector type intrinsics and vector instructions you want to use before you compile and/or execute.

I'm guessing your CPU is x86, but Windows should have a way to verify that. With Linux you can run something like grep avx2 /proc/cpuinfo.

Upvotes: 1

user149341
user149341

Reputation:

The tutorial you are trying to use is for SIMD programming for the Cell CPU (i.e, in the Playstation 3). It is not applicable to x86 programming.

Use a tutorial that is applicable to the compiler you are using (GCC, Clang, or Visual C++).

Upvotes: 2

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