[PATCH] D36621: [test-suite]: Adding SimpleMOC proxy-app.

[Hal Finkel via Phabricator via llvm-commits]

hfinkel added a comment.

In https://reviews.llvm.org/D36621#842247, @hfinkel wrote:

> This test does not have a numerical verification output, but nevertheless, I'd prefer that we not depend explicitly on libc's rand. Different libc implementations have different implementations of rand, and I'd rather not have that be a cause of any latter difficultly tracking down performance differences between systems/configurations.
>
> The easiest way to deal with this is probably to substitute our own rand implementation. I wrote one of these for the original XSBench patch (see glibc_compat_rand.{c.h} in https://reviews.llvm.org/D27311). Can you grab those files from there


As it turns out, those files were pretty broken. Here's a working source file:

  /*===------------ glibc_compat_rand.c - glibc rand emulation --------------===*\
   *
   *                     The LLVM Compiler Infrastructure
   *
   * This file is distributed under the University of Illinois Open Source
   * License. See LICENSE.TXT for details.
   *
  \*===----------------------------------------------------------------------===*/
  
  #include "glibc_compat_rand.h"
  
  /**
   * This rand implementation is designed to emulate the implementation of
   * rand/srand in recent versions of glibc. This is used for programs which
   * require this specific rand implementation in order to pass verification
   * tests.
   *
   * For more information, see: http://www.mathstat.dal.ca/~selinger/random/
   **/
  
  #define TABLE_SIZE 344
  static unsigned int table[TABLE_SIZE];
  static int next;
  
  int glibc_compat_rand(void) {
    /* Calculate the indices i-3 and i-31 in the circular vector. */
    int i3 = (next < 3) ? (TABLE_SIZE + next - 3) : (next - 3);
    int i31 = (next < 31) ? (TABLE_SIZE + next - 31) : (next - 31);
  
    table[next] = table[i3] + table[i31];
    unsigned int r = table[next] >> 1;
  
    ++next;
    if (next >= TABLE_SIZE)
      next = 0;
  
    return r;
  }
  
  void glibc_compat_srand(unsigned int seed) {
    if (seed == 0)
      seed = 1;
  
    table[0] = seed;
  
    for (int i = 1; i < 31; i++) {
      int r = (16807ll * table[i - 1]) % 2147483647;
      if (r < 0)
        r += 2147483647;
  
      table[i] = r;
    }
  
    for (int i = 31; i < 34; i++)
      table[i] = table[i - 31];
    for (int i = 34; i < TABLE_SIZE; i++)
      table[i] = table[i - 31] + table[i - 3];
  
    next = 0;
  }


Please use that instead.

> and add them to this patch and then, in SimpleMOC_header.h, add something like:
> 
>   #ifndef NO_GLIBC_COMPAT_RAND
>   #define rand glibc_compat_rand
>   #define srand glibc_compat_srand
>   #endif




https://reviews.llvm.org/D36621