https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106153
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|1 |0 Status|WAITING |UNCONFIRMED --- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- saved_stack.50_2 = __builtin_stack_save (); _ll_buf.24_379 = __builtin_alloca_with_align (/*size=*/32, /*align(bits)=*/64); _pbuf_381 = &MEM[(struct log_msg *)_ll_buf.24_379].data; MEM[(const void * *)_ll_buf.24_379 + 24B] = "Error message example."; MEM[(union cbprintf_package_hdr *)&hdr] = 4; MEM[(union cbprintf_package_hdr *)_ll_buf.24_379 + 16B] = hdr; hdr ={v} {CLOBBER}; MEM[(struct log_msg_desc *)&_desc] = 8256; z_log_msg_static_create (&log_const_syst, _desc, _pbuf_381, 0B); __builtin_stack_restore (saved_stack.50_2); The alloca gets expanded as: (insn 15 14 16 (set (reg/f:DI 31 sp) (plus:DI (reg/f:DI 31 sp) (const_int -32 [0xffffffffffffffe0]))) "/home/andyross/z/zephyr/samples/subsys/logging/syst/src/main.c":47:49 -1 (nil)) (insn 16 15 17 (set (reg:DI 214) (reg/f:DI 88 virtual-stack-dynamic)) "/home/andyross/z/zephyr/samples/subsys/logging/syst/src/main.c":47:49 -1 (nil)) (insn 17 16 18 (set (reg:DI 215) (plus:DI (reg:DI 214) (const_int 7 [0x7]))) "/home/andyross/z/zephyr/samples/subsys/logging/syst/src/main.c":47:49 -1 (nil)) (insn 18 17 19 (set (reg:DI 216) (lshiftrt:DI (reg:DI 215) (const_int 3 [0x3]))) "/home/andyross/z/zephyr/samples/subsys/logging/syst/src/main.c":47:49 -1 (expr_list:REG_EQUAL (udiv:DI (reg:DI 215) (const_int 8 [0x8])) (nil))) (insn 19 18 20 (set (reg/f:DI 217) (ashift:DI (reg:DI 216) (const_int 3 [0x3]))) "/home/andyross/z/zephyr/samples/subsys/logging/syst/src/main.c":47:49 -1 (nil)) (insn 20 19 0 (set (reg/f:DI 117 [ _ll_buf.24 ]) (reg/f:DI 217)) "/home/andyross/z/zephyr/samples/subsys/logging/syst/src/main.c":47:49 -1 (nil)) Which looks correct (64 bit aligned is 8 byte aligned).