https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126931
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Last reconfirmed| |2026-08-18
Priority|P3 |P4
Target Milestone|--- |17.0
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
this_iter = duplicate_insn_chain (head_insn, tail_insn, NULL, &id);
but tail_insn (65) is before head_insn (20):
(note 7 1 81 2 [bb 2] NOTE_INSN_BASIC_BLOCK)
...
(insn 65 13 15 2 (cond_exec (ne (reg:SI 1 A1)
(const_int 0 [0]))
(set (reg:QI 3 A3 [orig:76 a_lsm_flag.12 ] [76])
(const_int 1 [0x1])))
"/space/rguenther/src/gcc-clean/gcc/testsuite/gcc.c-torture/execute/pr64682.c":16:17
discrim 2 349 {*p movqi_insn}
(expr_list:REG_DEAD (reg:SI 1 A1)
(expr_list:REG_EQUAL (const_int 1 [0x1])
(nil))))
(code_label 15 65 16 3 8 (nil) [2 uses])
(note 16 15 17 3 [bb 3] NOTE_INSN_BASIC_BLOCK)
(note 17 16 20 3 NOTE_INSN_DELETED)
(jump_insn:TI 20 17 21 3 (parallel [
(set (pc)
(if_then_else (ne (reg:SI 0 A0 [orig:75 ivtmp_15 ] [75])
(const_int 1 [0x1]))
(label_ref:SI 15)
(pc)))
(set (reg:SI 0 A0 [orig:75 ivtmp_15 ] [75])
(plus:SI (reg:SI 0 A0 [orig:75 ivtmp_15 ] [75])
(const_int -1 [0xffffffffffffffff])))
(clobber (scratch:SI))
])
"/space/rguenther/src/gcc-clean/gcc/testsuite/gcc.c-torture/execute/pr64682.c":16:17
discrim 2 80 {loop_end}
(int_list:REG_BR_PROB 1054616657 (nil))
-> 15)
bb is loop->head (BB3),
tail_insn = prev_real_insn (BB_END (bb));
ends up before the loop. "oops"
