https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109093
--- Comment #19 from H.J. Lu <hjl.tools at gmail dot com> --- .DEFERRED_INIT has insn 259 261 297 4 (set (reg/f:DI 144) (plus:DI (reg/f:DI 19 frame) (const_int -32 [0xffffffffffffffe0]))) 241 {*leadi} (expr_list:REG_EQUAL (plus:DI (reg/f:DI 19 frame) (const_int -32 [0xffffffffffffffe0])) (nil))) vs explicit __builtin_memset insn 264 149 153 34 (set (reg/f:DI 144) (plus:DI (reg/f:DI 19 frame) (const_int -32 [0xffffffffffffffe0]))) 241 {*leadi} (expr_list:REG_EQUIV (plus:DI (reg/f:DI 19 frame) (const_int -32 [0xffffffffffffffe0])) (nil))) LRA can eliminate (reg/f:DI 144) with REG_EQUIV, but not with REG_EQUAL.