[Bug target/107183] [10/11/12/13 Regression] -fcompare-debug failure (length) with -fsanitize=float-cast-overflow since r7-5708-gcfd719e7769fd43f

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107183

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Seems the bug is in swap_rtx_condition.
It is called on:
(insn 10023 10021 10024 4 (set (reg:CCFP 17 flags)
        (unspec:CCFP [
                (compare:CCFP (reg:XF 9 st(1) [orig:84 _3 ] [84])
                    (reg:XF 8 st [107]))
            ] UNSPEC_NOTRAP)) "pr107183.c":6:18 discrim 1 45 {*cmpiuxf_i387}
     (expr_list:REG_DEAD (reg:XF 9 st(1) [orig:84 _3 ] [84])
        (expr_list:REG_DEAD (reg:XF 8 st [107])
            (nil))))
on the first next_flags_user call in the function it sets insn to:
(insn 10110 10024 10111 4 (set (reg:QI 3 bx [105])
        (unordered:QI (reg:CCFP 17 flags)
            (const_int 0 [0]))) "pr107183.c":6:18 discrim 1 949 {*setcc_qi}
     (nil))
(still the same between -g and -g0, but already that one could differ),
but then next_flags_user (the 3rd one in the function) finds
(debug_insn 4 10029 10030 4 (var_location:SI D#1 (if_then_else:SI (uneq
(reg:CCFP 17 flags)
            (const_int 0 [0]))
        (reg:SI 3 bx [105])
        (reg:SI 0 ax [111]))) -1
     (nil))
with -g and
(insn 10030 10029 10032 4 (set (reg:SI 3 bx [orig:90 iftmp.0_9 ] [90])
        (if_then_else:SI (uneq (reg:CCFP 17 flags)
                (const_int 0 [0]))
            (reg:SI 3 bx [105])
            (reg:SI 0 ax [111]))) "pr107183.c":6:18 discrim 1 1269
{*movsicc_noc}
     (expr_list:REG_DEAD (reg:CCFP 17 flags)
        (expr_list:REG_DEAD (reg:SI 0 ax [111])
            (expr_list:REG_EQUAL (if_then_else:SI (uneq (reg:CCFP 17 flags)
                        (const_int 0 [0]))
                    (reg:SI 3 bx [105])
                    (const_int 1 [0x1]))
                (nil)))))
with -g0.