[Bug target/125609] [17 Regression] internal compiler error: in single_pred_edge, at basic-block.h:337 bootstrapping GCC on LoongArch

[xry111 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125609

--- Comment #1 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
An interesting aspect: if I set STAGE1_CFLAGS=-O2 it fails building stage 2,
but if I don't set that it fails building stage 3.