https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78775
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> --- We're in operand_signed_p, checking whether an SSA_NAME d_4 is signed or not. We look at its SSA_NAME_DEF_STMT which is d_4 = PHI <0(2), d_5(5)> and we walk these phi arguments, and we call operand_signed_p (d_5), but its SSA_NAME_DEF_STMT is d_5 = PHI <d_4(3), d_8(4)> so we call operand_signed_p (d_4) again -> loop.
