[Bug debug/67355] [5 Regression] ICE compiling LTP testcase, endless cselib recursion from var-tracking

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67355

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |i?86-*-*
   Target Milestone|---                         |5.3
            Summary|[5 Regression] ICE          |[5 Regression] ICE
                   |compiling LTP testcase      |compiling LTP testcase,
                   |                            |endless cselib recursion
                   |                            |from var-tracking

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Delta-reduced (w/ includes):

#include <stdio.h>
double pi;
FILE *temp;
static int checkbuf(char *, int, int);
int main(int argc, char *argv[])
{
  register int i, j;
  char buf[100];
  for (i = 0; i < 30; i++)
    for (j = 0; j < 30; j++)
      {
        sprintf(buf, "%*.*f", i, j, pi);
        if (checkbuf(buf, i, j)) {
        }
      }
}
static int checkbuf(char *str, int n1, int n2)
{
  register int bd;
  /* before decimal point */    register int ad;
  /* after decimal point */     register int tw;
  /* total width */     register int dp;
  /* decimal point */   char *buf;
  bd = ad = dp = 0;
  while (*str && *str != '.') {
      bd++;
      str++;
  }
  if (*str == '.') {
      dp++;
      str++;
      if (*str) {
          while (*str) {
              ad++;
              str++;
          }
      }
  }
  tw = bd + dp + ad;
  if (tw < n1) {
      fprintf(temp, "\tWidth too small.\n");
      return (-1);
  }
  if (ad != n2) {
      fprintf(temp, "\tn1 = %d, n2 = %d, buf= '%s'\n", n1, n2, buf);
  }
  return (0);
}


Program received signal SIGSEGV, Segmentation fault.
0x00000000008a1732 in rtx_equal_for_cselib_1 (x=0x7ffff687c810, 
    y=0x7ffff687c7f8, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:1022
1022                  && targetm.commutative_p (x, UNKNOWN)
Missing separate debuginfos, use: zypper install
libgmp10-debuginfo-6.0.0-71.1.x86_64 libisl13-debuginfo-0.14-25.2.x86_64
libmpc3-debuginfo-1.0.2-38.2.x86_64 libmpfr4-debuginfo-3.1.2-3.1.2.x86_64
(gdb) bt
#0  0x00000000008a1732 in rtx_equal_for_cselib_1 (x=0x7ffff687c810, 
    y=0x7ffff687c7f8, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:1022
#1  0x00000000008a12bf in rtx_equal_for_cselib_1 (x=0x7ffff687c810, 
    y=0x235e920, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:924
#2  0x00000000008a17dd in rtx_equal_for_cselib_1 (x=0x7ffff687c7f8, 
    y=0x7ffff687c810, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:1026
#3  0x00000000008a1206 in rtx_equal_for_cselib_1 (x=0x235e920, 
    y=0x7ffff687c810, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:907
... (endless recursion)

entered via

#59 0x00000000008a1206 in rtx_equal_for_cselib_1 (x=0x235e938, 
    y=0x7ffff687c978, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:907
#60 0x00000000008a5b82 in cselib_hasher::equal (v=0x2294170, 
    x_arg=0x7fffffffbef0)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:150
#61 0x00000000008a5d42 in hash_table<cselib_hasher, xcallocator,
false>::find_slot_with_hash (this=0x22d53e0, comparable=0x7fffffffbef0,
hash=13065, 
    insert=INSERT)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/hash-table.h:999
#62 0x00000000008a0761 in cselib_find_slot (mode=SImode, x=0x7ffff687c978, 
    hash=13065, insert=INSERT, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:600
#63 0x00000000008a3b5f in cselib_lookup_1 (x=0x7ffff687c978, mode=SImode, 
    create=1, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:2082
#64 0x00000000008a3c71 in cselib_lookup (x=0x7ffff687c978, mode=SImode, 
    create=1, memmode=VOIDmode)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:2125
#65 0x00000000008a478f in cselib_add_permanent_equiv (elt=0x2328960, 
    x=0x7ffff687c978, insn=0x7ffff68196c0)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:2427
#66 0x0000000001099612 in reverse_op (val=0x235e938, expr=0x7ffff681a6a8, 
    insn=0x7ffff68196c0)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/var-tracking.c:5846
#67 0x000000000109a4b6 in add_stores (loc=0x7ffff687c960, expr=0x7ffff681a6a8, 
    cuip=0x7fffffffc250)
---Type <return> to continue, or q <return> to quit---
    at /space/rguenther/src/svn/gcc-5-branch/gcc/var-tracking.c:6114
#68 0x0000000000cfb3b0 in note_stores (x=0x7ffff681a6a8, 
    fun=0x1099617 <add_stores(rtx, const_rtx, void*)>, data=0x7fffffffc250)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/rtlanal.c:1652
#69 0x0000000000cfb3f7 in note_stores (x=0x7ffff680b680, 
    fun=0x1099617 <add_stores(rtx, const_rtx, void*)>, data=0x7fffffffc250)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/rtlanal.c:1657
#70 0x000000000109c929 in add_with_sets (insn=0x7ffff68196c0, 
    sets=0x7fffffffc350, n_sets=1)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/var-tracking.c:6559
#71 0x00000000008a4cf6 in cselib_record_sets (insn=0x7ffff68196c0)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:2574
#72 0x00000000008a52e6 in cselib_process_insn (insn=0x7ffff68196c0)
    at /space/rguenther/src/svn/gcc-5-branch/gcc/cselib.c:2686
#73 0x00000000010a7a79 in vt_initialize ()
    at /space/rguenther/src/svn/gcc-5-branch/gcc/var-tracking.c:10132
#74 0x00000000010a82de in variable_tracking_main_1 ()
    at /space/rguenther/src/svn/gcc-5-branch/gcc/var-tracking.c:10331
#75 0x00000000010a8408 in variable_tracking_main ()
    at /space/rguenther/src/svn/gcc-5-branch/gcc/var-tracking.c:10384

Can't reproduce on trunk.