https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87238
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |missed-optimization Target| |aarch64-*-* Version|unknown |7.3.0 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- >$ g++ -O3 -arch arm64 test.cpp -S -o - That command line is seems wrong. So does the output of the assembly code too. Anyways confirmed. mov x1, x2 mov x2, 256 add x29, sp, 0 .cfi_def_cfa_register 29 add x0, x29, 16 bl memcpy add x0, x29, 16 bl _Z13structByValue9BigStruct ldp x29, x30, [sp], 272