[Bug target/112483] [14 Regression] gfortran.dg/ieee/ieee_2.f90 fails on loongarch64-linux-gnu at -O1 or above

[xry111 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112483

--- Comment #4 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
In 268r.cse1:

(insn 26 25 27 2 (set (reg:SF 93)
        (mem/u/c:SF (reg/f:DI 94) [0  S4 A32])) "ieee_2.f90":13:6 discrim 4 146
{*movsf_hardfloat}
     (expr_list:REG_EQUAL (const_double:SF -1.0e+0 [-0x0.8p+1])
        (nil)))
(insn 27 26 28 2 (set (reg:SF 81 [ _8 ])
        (copysign:SF (reg/v:SF 80 [ sx1 ])
            (reg:SF 93))) "ieee_2.f90":13:6 discrim 4 63 {copysignsf3}
     (nil))

But in 269r.fwprop1:

(insn 27 24 28 2 (set (reg:SF 81 [ _8 ])
        (neg:SF (reg/v:SF 80 [ sx1 ]))) "ieee_2.f90":13:6 discrim 4 89 {negsf2}
     (expr_list:REG_DEAD (reg:SF 93)
        (nil)))

???