https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81825
--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
BTW, GCC 8 -O2 generates
.file "foo.i"
.text
.p2align 4,,15
.globl func
.type func, @function
func:
.LFB0:
.cfi_startproc
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset 6, -16
movq %rsp, %rbp
.cfi_def_cfa_register 6
andq $-32, %rsp
leave
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE0:
.size func, .-func
.ident "GCC: (GNU) 8.0.0 20170810 (experimental)"
.section .note.GNU-stack,"",@progbits
