[Bug middle-end/106495] [13 Regression] Build fails gcc/tree-ssa-threadbackward.cc:22: gcc/vec.h:890:19: error: array subscript 4294967294 is above array bounds of 'basic_block_def* [1]' [-Werror=array-bounds]

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106495

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, so it's indeed an isolated path we warn on:

<bb 111> [local count: 2735590]:
_46 = global_options.x_param_max_fsm_thread_path_insns;
if (_46 <= n_insns_157)
  goto <bb 113>; [34.00%]
else
  goto <bb 116>; [66.00%]

<bb 116> [local count: 1805491]:
n_insns_346 = ASSERT_EXPR <n_insns_157, n_insns_157 < _46>;
_233 = m_path_340->m_vec;
if (_233 != 0B)
  goto <bb 119>; [70.00%]
else
  goto <bb 175>; [30.00%]

<bb 175> [local count: 541647]:
_379 = ASSERT_EXPR <_233, _233 == 0B>;

<bb 117> [local count: 541647]:
_286 = MEM[(struct vec *)0B].m_vecpfx.m_num;
_381 = ASSERT_EXPR <0B, 0B != 0B>;
if (_286 != 4294967295)
  goto <bb 120>; [0.00%]
else
  goto <bb 118>; [100.00%]

<bb 118> [local count: 541647]:
_391 = ASSERT_EXPR <4294967294, 4294967294 < _286>;
_290 = MEM <struct vec> [(struct basic_block_def * const
&)_381].m_vecdata[4294967294];
goto <bb 122>; [100.00%]