[Bug rtl-optimization/96865] New: ICE in hash_rtx_cb, at cse.c:2548

[Bug rtl-optimization/96865] New: ICE in hash_rtx_cb, at cse.c:2548

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96865

            Bug ID: 96865
           Summary: ICE in hash_rtx_cb, at cse.c:2548
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---
            Target: powerpc-*-linux-gnu

gcc-11.0.0-alpha20200830 snapshot (g:6ccadc4c0486ff011a32c74de1a31148acb3cbe2)
ICEs when compiling the following testcase, reduced from
gcc/testsuite/gcc.target/sparc/tls-ld-uint16.c, w/ -m32 -O2 -fPIC
-fselective-scheduling:

__thread int ky __attribute__ ((tls_model ("local-dynamic")));

void
y9 (int cw)
{
  ky = cw;
}

% powerpc-e300c3-linux-gnu-gcc-11.0.0 -m32 -O2 -fPIC -fselective-scheduling -c
ggkraci7.c
during RTL pass: sched1
ggkraci7.c: In function 'y9':
ggkraci7.c:7:1: internal compiler error: in hash_rtx_cb, at cse.c:2548
    7 | }
      | ^
0x75e4f1 hash_rtx_cb(rtx_def const*, machine_mode, int*, int*, bool, int
(*)(rtx_def const*, machine_mode, rtx_def**, machine_mode*))
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/cse.c:2548
0x159e1fc hash_rtx_cb(rtx_def const*, machine_mode, int*, int*, bool, int
(*)(rtx_def const*, machine_mode, rtx_def**, machine_mode*))
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/cse.c:2526
0xd3eff8 vinsn_init
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched-ir.c:1199
0xd4243f vinsn_create
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched-ir.c:1231
0xd4243f init_global_and_expr_for_insn
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched-ir.c:3028
0xd352db sched_scan
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched-ir.c:2818
0xd3804a sel_init_global_and_expr(vec<basic_block_def*, va_heap, vl_ptr>)
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched-ir.c:3050
0xd52743 sel_region_init
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched.c:6901
0xd52743 sel_sched_region(int)
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched.c:7624
0xd53c59 run_selective_scheduling()
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sel-sched.c:7720
0xd33904 rest_of_handle_sched
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sched-rgn.c:3724
0xd33904 execute
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-11.0.0_alpha20200830/work/gcc-11-20200830/gcc/sched-rgn.c:3834

[Bug rtl-optimization/96865] ICE in hash_rtx_cb, at cse.c:2548

[jeevitha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96865

Jeevitha <jeevitha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jeevitha at gcc dot gnu.org

--- Comment #1 from Jeevitha <jeevitha at gcc dot gnu.org> ---
The issue was in the following RTL,
(insn 6 2 21 2 (parallel [
            (set (reg:SI 96 lr)
                (unspec:SI [
                        (symbol_ref:SI ("_GLOBAL_OFFSET_TABLE_") [flags 0x42])
                        (label_ref 0)
                    ] UNSPEC_TOCPTR))
            (code_label 0 0 0 2 (nil) [2 uses])
        ]) "test.c":6:6 798 {load_toc_v4_PIC_1b_normal}

The above RTL will generate the following assembly:

        bcl 20,31,$+8

There is no need for 'label_ref 0' and 'code_label' in the RTL instruction, as
the assembly does not require them. Is my understanding correct?

Currently, we are encountering an ICE due to the following reason: In the
'hash_rtx' function [cse.cc], handling for 'LABEL_REF' is present but not for
'code_label', causing it to not return a hash directly. Instead, it searches
for the format corresponding to '(code_label 0 0 0 4 (nil))', which is
"uuB00is". In the provided code snippet below, 'B' and 'u' do not have case
handling, leading to a 'gcc_unreachable'. This is the reason for the ICE
currently.


fmt = GET_RTX_FORMAT (code);  //code -> code_label
  for (; i >= 0; i--)
    {
      switch (fmt[i])
        {
        case 'e':
          /* If we are about to do the last recursive call
             needed at this level, change it into iteration.
             This function  is called enough to be worth it.  */
          if (i == 0)
            {
              x = XEXP (x, i);
              goto repeat;
            }

          hash += hash_rtx (XEXP (x, i), VOIDmode, do_not_record_p,
                            hash_arg_in_memory_p,
                            have_reg_qty, cb);
          break;

        case 'E':
          for (j = 0; j < XVECLEN (x, i); j++)
            hash += hash_rtx (XVECEXP (x, i, j), VOIDmode, do_not_record_p,
                              hash_arg_in_memory_p,
                              have_reg_qty, cb);
          break;

        case 's':
          hash += hash_rtx_string (XSTR (x, i));
          break;

        case 'i':
          hash += (unsigned int) XINT (x, i);
          break;

        case 'p':
          hash += constant_lower_bound (SUBREG_BYTE (x));
          break;

        case '0': case 't':
          /* Unused.  */
          break;

        default:
          gcc_unreachable ();
        }
    }

To address this, I've removed 'operand1' and adjusted the respective
'match_dup' to 'operand0' in the below pattern.

(define_insn "load_toc_v4_PIC_1b_normal"
  [(set (reg:SI LR_REGNO)
        (unspec:SI [(match_operand:SI 0 "immediate_operand" "s")
                    (label_ref (match_operand 1 "" ""))]
                UNSPEC_TOCPTR))
   (match_dup 1)]

After implementing the mentioned change, there were no ICEs or regressions. Is
this approach correct?

[Bug rtl-optimization/96865] ICE in hash_rtx_cb, at cse.c:2548

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96865

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

[Bug rtl-optimization/96865] ICE in hash_rtx_cb, at cse.c:2548

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96865

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |12.0, 13.0, 14.0

--- Comment #2 from Peter Bergner <bergner at gcc dot gnu.org> ---
Fails on trunk and basically all earlier versions.

[Bug rtl-optimization/96865] ICE in hash_rtx_cb, at cse.c:2548

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96865

Segher Boessenkool <segher at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |abel at ispras dot ru

--- Comment #3 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Yup.  I thought there would be missing options needed for this to fail (-mcpu=
for example), but it fails with plain trunk.

Something with sel-sched.  It works fine without that.

Putting the maintainers of selective scheduling on Cc:.

[Bug rtl-optimization/96865] ICE in hash_rtx_cb, at cse.c:2548

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96865

--- Comment #4 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Well, I wanted to add Alex as well, but BZ does not allow that?  Says he does
not exist?

Is there some other mail address than that mentioned in MAINTAINERS, the one he
usually uses, that works, maybe @gcc.gnu.org?