[Bug c/54894] New: internal compiler error: in vect_get_vec_def_for_operand, at tree-vect-stmts.c:1286

[kuszmaul at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54894

             Bug #: 54894
           Summary: internal compiler error: in
                    vect_get_vec_def_for_operand, at
                    tree-vect-stmts.c:1286
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: kuszmaul@gmail.com


Created attachment 28415
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28415
preprocessed code for matrix multiply

I'm having trouble getting gcc to remember alignment information the attached
matrix multiplication code.  So I introduced a temporary variable that is a
pointer to a 16-byte aligned double, and ended up with this error:


$ gcc -O3 -std=c99 mm_tile.c -Wcast-align -o mm_tile
mm_tile.c: In function ‘main’:
mm_tile.c:46:5: internal compiler error: in vect_get_vec_def_for_operand, at
tree-vect-stmts.c:1286
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://bugzilla.redhat.com/bugzilla> for instructions.
Preprocessed source stored into /tmp/ccvYpDPi.out file, please attach this to
your bugreport.
$ gcc --version
gcc (GCC) 4.7.2 20120921 (Red Hat 4.7.2-2)
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ cat mm_tile.c
/** BEGIN HIDDEN **/
#include <stdlib.h>
#include <stdio.h>
#include <sys/time.h>

typedef unsigned long long uint64_t;

/* Allow us to change n on the compiler command line with for example -Dn=1024
*/
#ifndef n
#define n 4096
#endif
double A[n][n] __attribute__((aligned(16)));
double B[n][n] __attribute__((aligned(16)));
double C[n][n] __attribute__((aligned(16)));

static float tdiff (struct timeval *start,
            struct timeval *end) {
  return (end->tv_sec-start->tv_sec)
    +1e-6*(end->tv_usec-start->tv_usec);
}

#include "verify.h"

#define tilesize 128

/* void mmbase (double *restrict C, double *restrict A, double *restrict B) {
*/
/*   for (int kh = 0; kh < n; kh += tilesize) { */
/*     for (int il = 0; il < tilesize; il++) { */
/*       for (int kl = 0; kl < tilesize; ++kl) { */
/*         for (int jl = 0; jl < tilesize; jl++) { */
/*           C[il*n+jl] += A[il*n+kh+kl]*B[(kh+kl)*n+jl]; */
/*         } */
/*       } */
/*     } */
/*   } */
/* } */

/* void mm_js(double *restrict C, double *restrict A, double *restrict B) { */
/*   for (int jh = 0; jh < n; jh += tilesize) { */
/*     mmbase(&C[jh], &A[0], &B[jh]); */
/*   } */
/* } */

typedef double adouble __attribute__((__aligned__(16)));

int main(int argc, const char *argv[]) {
  parse_args(argc, argv);
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      A[i][j] = (double)rand() / (double)RAND_MAX;
      B[i][j] = (double)rand() / (double)RAND_MAX;
      C[i][j] = 0;
    } }

  struct timeval start, end;
  gettimeofday(&start, NULL);
  /** END HIDDEN **/
  for (int ih = 0; ih < n; ih += tilesize) {                  
///\lilabel{block_loop_i}
    for (int jh = 0; jh < n; jh += tilesize) {                
///\lilabel{block_loop_k}
      for (int kh = 0; kh < n; kh += tilesize) {                     
///\lilabel{block_loop_j}
        for (int il = 0; il < tilesize; ++il) {                      
///\lilabel{base_loop_i}
          adouble *Ap = (adouble *)&A[ih+il][kh];
          for (int kl = 0; kl < tilesize; ++kl) {              
///\lilabel{base_loop_k}
            for (int jl = 0; jl < tilesize; ++jl) {                    
///\lilabel{base_loop_j}
              C[ih+il][jh+jl] += Ap[kl] * B[kh+kl][jh+jl];
///\lilabel{base_multiply}
        } } }
      }
      /* mmbase(&C[ih][jh],&A[ih][0],&B[0][jh]); */
    }
    /* mm_js(&C[ih][0], &A[ih][0], &B[0][0]); */
  }
  /** BEGIN HIDDEN **/
  gettimeofday(&end, NULL);
  printf("%0.6f\n", tdiff(&start, &end));
  if (need_to_verify) verify();
  return 0;
}
/** END HIDDEN **/