1  /* PR rtl-optimization/28982.  Function foo() does the equivalent of:
       2  
       3       float tmp_results[NVARS];
       4       for (int i = 0; i < NVARS; i++)
       5         {
       6  	 int inc = incs[i];
       7  	 float *ptr = ptrs[i], result = 0;
       8  	 for (int j = 0; j < n; j++)
       9  	   result += *ptr, ptr += inc;
      10  	 tmp_results[i] = result;
      11         }
      12       memcpy (results, tmp_results, sizeof (results));
      13  
      14     but without the outermost loop.  The idea is to create high register
      15     pressure and ensure that some INC and PTR variables are spilled.
      16  
      17     On ARM targets, sequences like "result += *ptr, ptr += inc" can
      18     usually be implemented using (mem (post_modify ...)), and we do
      19     indeed create such MEMs before reload for this testcase.  However,
      20     (post_modify ...) is not a valid address for coprocessor loads, so
      21     for -mfloat-abi=softfp, reload reloads the POST_MODIFY into a base
      22     register.  GCC did not deal correctly with cases where the base and
      23     index of the POST_MODIFY are themselves reloaded.  */
      24  #define NITER 4
      25  #define NVARS 20
      26  #define MULTI(X) \
      27    X( 0), X( 1), X( 2), X( 3), X( 4), X( 5), X( 6), X( 7), X( 8), X( 9), \
      28    X(10), X(11), X(12), X(13), X(14), X(15), X(16), X(17), X(18), X(19)
      29  
      30  #define DECLAREI(INDEX) inc##INDEX = incs[INDEX]
      31  #define DECLAREF(INDEX) *ptr##INDEX = ptrs[INDEX], result##INDEX = 0
      32  #define LOOP(INDEX) result##INDEX += *ptr##INDEX, ptr##INDEX += inc##INDEX
      33  #define COPYOUT(INDEX) results[INDEX] = result##INDEX
      34  
      35  float *ptrs[NVARS];
      36  float results[NVARS];
      37  int incs[NVARS];
      38  
      39  void __attribute__((noinline))
      40  foo (int n)
      41  {
      42    int MULTI (DECLAREI);
      43    float MULTI (DECLAREF);
      44    while (n--)
      45      MULTI (LOOP);
      46    MULTI (COPYOUT);
      47  }
      48  
      49  float input[NITER * NVARS];
      50  
      51  int
      52  main (void)
      53  {
      54    int i;
      55  
      56    for (i = 0; i < NVARS; i++)
      57      ptrs[i] = input + i, incs[i] = i;
      58    for (i = 0; i < NITER * NVARS; i++)
      59      input[i] = i;
      60    foo (NITER);
      61    for (i = 0; i < NVARS; i++)
      62      if (results[i] != i * NITER * (NITER + 1) / 2)
      63        return 1;
      64    return 0;
      65  }