[Bug target/88308] ICE in maybe_record_trace_start, at dwarf2cfi.c:2309

[acsawdey at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88308

--- Comment #3 from acsawdey at gcc dot gnu.org ---
One difference between compiling this -m32 and -m64 is that the label for the
jump table is marked /s in the 64-bit version:

(code_label/s 22 21 23 4 (nil) [4 uses])
(jump_table_data 23 22 24 (addr_diff_vec:SI (label_ref:DI 22)
         [
            (label_ref:DI 25)
            (label_ref:DI 54)
            (label_ref:DI 83)

In the 32-bit version it is not, and that label plus the jump_table_data insn
that follows are not present in the dumps after split2:

(code_label 23 22 24 4 (nil) [4 uses])
;; Insn is not within a basic block
(jump_table_data 24 23 25 (addr_diff_vec:SI (label_ref:SI 23)
         [
            (label_ref:SI 26)
            (label_ref:SI 64)
            (label_ref:SI 102)
            (label_ref:SI 140)
            (label_ref:SI 178)

The significance of this is that tablejump_p() looks at the next insn to
determine if it is in fact a tablejump:

bool
tablejump_p (const rtx_insn *insn, rtx_insn **labelp,
             rtx_jump_table_data **tablep)
{
  if (!JUMP_P (insn))
    return false;

  rtx target = JUMP_LABEL (insn);
  if (target == NULL_RTX || ANY_RETURN_P (target))
    return false;

  rtx_insn *label = as_a<rtx_insn *> (target);
  rtx_insn *table = next_insn (label);
  if (table == NULL_RTX || !JUMP_TABLE_DATA_P (table))
    return false;

Since the label insn and jump table insn seem to be gone, this return false.

Then in create_trace_edges() we end up in the final stanza of the if
(JUMP_P(insn):

      else
        {
          rtx_insn *lab = JUMP_LABEL_AS_INSN (insn);
          gcc_assert (lab != NULL);
          maybe_record_trace_start (lab, insn);
        }

And so we try to create a trace for the jump table label which leads to the
ICE.