https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112415
--- Comment #39 from John David Anglin <danglin at gcc dot gnu.org> --- In the f-m-o pass, the following three insns that set call clobbered registers r20-r22 are pulled from loop: (insn 186 183 190 29 (set (reg/f:SI 22 %r22 [478]) (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]) (const_int 388 [0x184]))) "../Python/compile.c":5964:9 120 {addsi3} (nil)) (insn 190 186 187 29 (set (reg/f:SI 21 %r21 [479]) (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]) (const_int 392 [0x188]))) "../Python/compile.c":5964:9 120 {addsi3} (nil)) (insn 194 191 195 29 (set (reg/f:SI 20 %r20 [480]) (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]) (const_int 396 [0x18c]))) "../Python/compile.c":5964:9 120 {addsi3} (nil)) They are used in the following insns before call to compiler_visit_expr1: (insn 242 238 258 32 (set (mem:SI (reg/f:SI 22 %r22 [478]) [4 MEM[(int *)prephit mp_37 + 388B]+0 S4 A32]) (reg:SI 23 %r23 [orig:173 vect__102.2442 ] [173])) "../Python/compile.c" :5968:22 42 {*pa.md:2193} (expr_list:REG_DEAD (reg:SI 23 %r23 [orig:173 vect__102.2442 ] [173]) (expr_list:REG_DEAD (reg/f:SI 22 %r22 [478]) (nil)))) (insn 258 242 246 32 (set (reg:SI 26 %r26) (reg/v/f:SI 5 %r5 [orig:198 c ] [198])) "../Python/compile.c":5969:15 42 {*pa.md:2193} (nil)) (insn 246 258 250 32 (set (mem:SI (reg/f:SI 21 %r21 [479]) [4 MEM[(int *)prephitmp_37 + 392B]+0 S4 A32]) (reg:SI 29 %r29 [orig:169 vect__102.2443 ] [169])) "../Python/compile.c":5968:22 42 {*pa.md:2193} (expr_list:REG_DEAD (reg:SI 29 %r29 [orig:169 vect__102.2443 ] [169]) (expr_list:REG_DEAD (reg/f:SI 21 %r21 [479]) (nil)))) (insn 250 246 254 32 (set (mem:SI (reg/f:SI 20 %r20 [480]) [4 MEM[(int *)prephitmp_37 + 396B]+0 S4 A32]) (reg:SI 31 %r31 [orig:145 vect__102.2444 ] [145])) "../Python/compile.c":5968:22 42 {*pa.md:2193} (expr_list:REG_DEAD (reg:SI 31 %r31 [orig:145 vect__102.2444 ] [145]) (expr_list:REG_DEAD (reg/f:SI 20 %r20 [480]) (nil)))) After the call, we have: (insn 1241 269 273 30 (set (reg/f:SI 22 %r22 [478]) (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])) "../Python/compile.c":5970:20 -1 (nil)) (insn 273 1241 1242 30 (set (mem:SI (plus:SI (reg/f:SI 22 %r22 [478]) (const_int 388 [0x184])) [4 MEM[(int *)_107 + 388B]+0 S4 A32]) (reg:SI 14 %r14 [orig:167 vect_pretmp_36.2450 ] [167])) "../Python/compile.c":5970:20 42 {*pa.md:2193} (nil)) (insn 1242 273 277 30 (set (reg/f:SI 21 %r21 [479]) (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])) "../Python/compile.c":5970:20 -1 (nil)) (insn 277 1242 1243 30 (set (mem:SI (plus:SI (reg/f:SI 21 %r21 [479]) (const_int 392 [0x188])) [4 MEM[(int *)_107 + 392B]+0 S4 A32]) (reg:SI 13 %r13 [orig:156 vect_pretmp_36.2451 ] [156])) "../Python/compile.c":5970:20 42 {*pa.md:2193} (nil)) (insn 1243 277 281 30 (set (reg/f:SI 20 %r20 [480]) (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])) "../Python/compile.c":5970:20 -1 (nil)) (insn 281 1243 299 30 (set (mem:SI (plus:SI (reg/f:SI 20 %r20 [480]) (const_int 396 [0x18c])) [4 MEM[(int *)_107 + 396B]+0 S4 A32]) (reg:SI 12 %r12 [orig:134 vect_pretmp_36.2452 ] [134])) "../Python/compile.c":5970:20 42 {*pa.md:2193} (nil)) We have lost the offsets that were added initially to r20, r21 and r22. Previous ce3 pass had: (insn 272 269 273 30 (set (reg/f:SI 22 %r22 [478]) (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]) (const_int 388 [0x184]))) "../Python/compile.c":5970:20 120 {addsi3} (nil)) (insn 273 272 276 30 (set (mem:SI (reg/f:SI 22 %r22 [478]) [4 MEM[(int *)_107 + 388B]+0 S4 A32]) (reg:SI 14 %r14 [orig:167 vect_pretmp_36.2450 ] [167])) "../Python/compile.c":5970:20 42 {*pa.md:2193} (nil)) (insn 276 273 277 30 (set (reg/f:SI 21 %r21 [479]) (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]) (const_int 392 [0x188]))) "../Python/compile.c":5970:20 120 {addsi3} (nil)) (insn 277 276 280 30 (set (mem:SI (reg/f:SI 21 %r21 [479]) [4 MEM[(int *)_107 + 392B]+0 S4 A32]) (reg:SI 13 %r13 [orig:156 vect_pretmp_36.2451 ] [156])) "../Python/compile.c":5970:20 42 {*pa.md:2193} (nil)) (insn 280 277 281 30 (set (reg/f:SI 20 %r20 [480]) (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]) (const_int 396 [0x18c]))) "../Python/compile.c":5970:20 120 {addsi3} (nil)) (insn 281 280 284 30 (set (mem:SI (reg/f:SI 20 %r20 [480]) [4 MEM[(int *)_107 + 396B]+0 S4 A32]) (reg:SI 12 %r12 [orig:134 vect_pretmp_36.2452 ] [134])) "../Python/compile.c":5970:20 42 {*pa.md:2193} (nil)) So, this is a f-m-o bug.