This is a pristine r353733 kernel, where *only* uma_core.c was compiled with "-O0":

(kgdb) disassemble uma_vm_zone_stats
Dump of assembler code for function uma_vm_zone_stats:
0xffffffff80f13060 <uma_vm_zone_stats+0>:       push   %rbp
0xffffffff80f13061 <uma_vm_zone_stats+1>:       mov    %rsp,%rbp
0xffffffff80f13064 <uma_vm_zone_stats+4>:       sub    $0x40,%rsp
0xffffffff80f13068 <uma_vm_zone_stats+8>:       mov    %r8b,%al
0xffffffff80f1306b <uma_vm_zone_stats+11>:      mov    %rdi,-0x8(%rbp)
0xffffffff80f1306f <uma_vm_zone_stats+15>:      mov    %rsi,-0x10(%rbp)
0xffffffff80f13073 <uma_vm_zone_stats+19>:      mov    %rdx,-0x18(%rbp)
0xffffffff80f13077 <uma_vm_zone_stats+23>:      mov    %rcx,-0x20(%rbp)
0xffffffff80f1307b <uma_vm_zone_stats+27>:      and    $0x1,%al
0xffffffff80f1307d <uma_vm_zone_stats+29>:      mov    %al,-0x21(%rbp)
0xffffffff80f13080 <uma_vm_zone_stats+32>:      movl   $0x0,-0x3c(%rbp)
0xffffffff80f13087 <uma_vm_zone_stats+39>:      mov    -0x3c(%rbp),%eax
0xffffffff80f1308a <uma_vm_zone_stats+42>:      mov    0xffffffff818018f0,%ecx
0xffffffff80f13091 <uma_vm_zone_stats+49>:      cmp    %ecx,%eax
0xffffffff80f13093 <uma_vm_zone_stats+51>:      jge    0xffffffff80f130d7 <uma_vm_zone_stats+119>
0xffffffff80f13099 <uma_vm_zone_stats+57>:      mov    -0x10(%rbp),%rax
0xffffffff80f1309d <uma_vm_zone_stats+61>:      mov    0x8(%rax),%rax
0xffffffff80f130a1 <uma_vm_zone_stats+65>:      movslq -0x3c(%rbp),%rcx
0xffffffff80f130a5 <uma_vm_zone_stats+69>:      imul   $0x30,%rcx,%rcx
0xffffffff80f130a9 <uma_vm_zone_stats+73>:      add    %rcx,%rax
0xffffffff80f130ac <uma_vm_zone_stats+76>:      mov    %rax,-0x30(%rbp)
0xffffffff80f130b0 <uma_vm_zone_stats+80>:      mov    -0x30(%rbp),%rax
0xffffffff80f130b4 <uma_vm_zone_stats+84>:      mov    0x10(%rax),%rax
0xffffffff80f130b8 <uma_vm_zone_stats+88>:      mov    -0x8(%rbp),%rcx
0xffffffff80f130bc <uma_vm_zone_stats+92>:      mov    0x3c(%rcx),%edx
0xffffffff80f130bf <uma_vm_zone_stats+95>:      mov    %edx,%esi
0xffffffff80f130c1 <uma_vm_zone_stats+97>:      add    %rax,%rsi
0xffffffff80f130c4 <uma_vm_zone_stats+100>:     mov    %esi,%edx
0xffffffff80f130c6 <uma_vm_zone_stats+102>:     mov    %edx,0x3c(%rcx)
0xffffffff80f130c9 <uma_vm_zone_stats+105>:     mov    -0x3c(%rbp),%eax
0xffffffff80f130cc <uma_vm_zone_stats+108>:     add    $0x1,%eax
0xffffffff80f130cf <uma_vm_zone_stats+111>:     mov    %eax,-0x3c(%rbp)
0xffffffff80f130d2 <uma_vm_zone_stats+114>:     jmpq   0xffffffff80f13087 <uma_vm_zone_stats+39>
0xffffffff80f130d7 <uma_vm_zone_stats+119>:     mov    -0x10(%rbp),%rax
0xffffffff80f130db <uma_vm_zone_stats+123>:     mov    0xf8(%rax),%rdi
0xffffffff80f130e2 <uma_vm_zone_stats+130>:     callq  0xffffffff80c13f20 <counter_u64_fetch>
0xffffffff80f130e7 <uma_vm_zone_stats+135>:     mov    -0x8(%rbp),%rdi
0xffffffff80f130eb <uma_vm_zone_stats+139>:     mov    %rax,0x48(%rdi)
0xffffffff80f130ef <uma_vm_zone_stats+143>:     mov    -0x10(%rbp),%rax
0xffffffff80f130f3 <uma_vm_zone_stats+147>:     mov    0x100(%rax),%rdi
0xffffffff80f130fa <uma_vm_zone_stats+154>:     callq  0xffffffff80c13f20 <counter_u64_fetch>
0xffffffff80f130ff <uma_vm_zone_stats+159>:     mov    -0x8(%rbp),%rdi
0xffffffff80f13103 <uma_vm_zone_stats+163>:     mov    %rax,0x50(%rdi)
0xffffffff80f13107 <uma_vm_zone_stats+167>:     mov    -0x10(%rbp),%rax
0xffffffff80f1310b <uma_vm_zone_stats+171>:     mov    0x108(%rax),%rdi
0xffffffff80f13112 <uma_vm_zone_stats+178>:     callq  0xffffffff80c13f20 <counter_u64_fetch>
0xffffffff80f13117 <uma_vm_zone_stats+183>:     mov    -0x8(%rbp),%rdi
0xffffffff80f1311b <uma_vm_zone_stats+187>:     mov    %rax,0x58(%rdi)
0xffffffff80f1311f <uma_vm_zone_stats+191>:     mov    -0x10(%rbp),%rax
0xffffffff80f13123 <uma_vm_zone_stats+195>:     mov    0x110(%rax),%rax
0xffffffff80f1312a <uma_vm_zone_stats+202>:     mov    -0x8(%rbp),%rdi
0xffffffff80f1312e <uma_vm_zone_stats+206>:     mov    %rax,0x60(%rdi)
0xffffffff80f13132 <uma_vm_zone_stats+210>:     mov    -0x10(%rbp),%rax
0xffffffff80f13136 <uma_vm_zone_stats+214>:     mov    0x118(%rax),%rax
0xffffffff80f1313d <uma_vm_zone_stats+221>:     mov    -0x8(%rbp),%rdi
0xffffffff80f13141 <uma_vm_zone_stats+225>:     mov    %rax,0x68(%rdi)
0xffffffff80f13145 <uma_vm_zone_stats+229>:     movl   $0x0,-0x3c(%rbp)
0xffffffff80f1314c <uma_vm_zone_stats+236>:     mov    -0x3c(%rbp),%eax
0xffffffff80f1314f <uma_vm_zone_stats+239>:     mov    0xffffffff81dd6218,%ecx
0xffffffff80f13156 <uma_vm_zone_stats+246>:     add    $0x1,%ecx
0xffffffff80f13159 <uma_vm_zone_stats+249>:     cmp    %ecx,%eax
0xffffffff80f1315b <uma_vm_zone_stats+251>:     jae    0xffffffff80f132e6 <uma_vm_zone_stats+646>
0xffffffff80f13161 <uma_vm_zone_stats+257>:     xor    %eax,%eax
0xffffffff80f13163 <uma_vm_zone_stats+259>:     mov    -0x20(%rbp),%rcx
0xffffffff80f13167 <uma_vm_zone_stats+263>:     movslq -0x3c(%rbp),%rdx
0xffffffff80f1316b <uma_vm_zone_stats+267>:     shl    $0x6,%rdx
0xffffffff80f1316f <uma_vm_zone_stats+271>:     add    %rdx,%rcx
0xffffffff80f13172 <uma_vm_zone_stats+274>:     movq   $0x0,0x38(%rcx)
0xffffffff80f1317a <uma_vm_zone_stats+282>:     movq   $0x0,0x30(%rcx)
0xffffffff80f13182 <uma_vm_zone_stats+290>:     movq   $0x0,0x28(%rcx)
0xffffffff80f1318a <uma_vm_zone_stats+298>:     movq   $0x0,0x20(%rcx)
0xffffffff80f13192 <uma_vm_zone_stats+306>:     movq   $0x0,0x18(%rcx)
0xffffffff80f1319a <uma_vm_zone_stats+314>:     movq   $0x0,0x10(%rcx)
0xffffffff80f131a2 <uma_vm_zone_stats+322>:     movq   $0x0,0x8(%rcx)
0xffffffff80f131aa <uma_vm_zone_stats+330>:     movq   $0x0,(%rcx)
0xffffffff80f131b1 <uma_vm_zone_stats+337>:     testb  $0x1,-0x21(%rbp)
0xffffffff80f131b5 <uma_vm_zone_stats+341>:     mov    %eax,-0x40(%rbp)
0xffffffff80f131b8 <uma_vm_zone_stats+344>:     jne    0xffffffff80f131ee <uma_vm_zone_stats+398>
0xffffffff80f131be <uma_vm_zone_stats+350>:     movslq -0x3c(%rbp),%rax
0xffffffff80f131c2 <uma_vm_zone_stats+354>:     shr    $0x6,%rax
0xffffffff80f131c6 <uma_vm_zone_stats+358>:     lea    -0x7e229e50(,%rax,8),%rax
0xffffffff80f131ce <uma_vm_zone_stats+366>:     mov    (%rax),%rax
0xffffffff80f131d1 <uma_vm_zone_stats+369>:     movslq -0x3c(%rbp),%rcx
0xffffffff80f131d5 <uma_vm_zone_stats+373>:     and    $0x3f,%rcx
0xffffffff80f131d9 <uma_vm_zone_stats+377>:     mov    $0x1,%edx
0xffffffff80f131de <uma_vm_zone_stats+382>:     shl    %cl,%rdx
0xffffffff80f131e1 <uma_vm_zone_stats+385>:     and    %rdx,%rax
0xffffffff80f131e4 <uma_vm_zone_stats+388>:     cmp    $0x0,%rax
0xffffffff80f131e8 <uma_vm_zone_stats+392>:     jne    0xffffffff80f131f3 <uma_vm_zone_stats+403>
0xffffffff80f131ee <uma_vm_zone_stats+398>:     jmpq   0xffffffff80f132d8 <uma_vm_zone_stats+632>
0xffffffff80f131f3 <uma_vm_zone_stats+403>:     mov    -0x10(%rbp),%rax
0xffffffff80f131f7 <uma_vm_zone_stats+407>:     add    $0x180,%rax
0xffffffff80f131fd <uma_vm_zone_stats+413>:     movslq -0x3c(%rbp),%rcx
0xffffffff80f13201 <uma_vm_zone_stats+417>:     shl    $0x7,%rcx
0xffffffff80f13205 <uma_vm_zone_stats+421>:     add    %rcx,%rax
0xffffffff80f13208 <uma_vm_zone_stats+424>:     mov    %rax,-0x38(%rbp)
0xffffffff80f1320c <uma_vm_zone_stats+428>:     mov    -0x38(%rbp),%rax
0xffffffff80f13210 <uma_vm_zone_stats+432>:     cmpq   $0x0,0x8(%rax)
0xffffffff80f13215 <uma_vm_zone_stats+437>:     je     0xffffffff80f1323f <uma_vm_zone_stats+479>
0xffffffff80f1321b <uma_vm_zone_stats+443>:     mov    -0x38(%rbp),%rax
0xffffffff80f1321f <uma_vm_zone_stats+447>:     mov    0x8(%rax),%rax
0xffffffff80f13223 <uma_vm_zone_stats+451>:     movswq 0x10(%rax),%rax
0xffffffff80f13228 <uma_vm_zone_stats+456>:     mov    -0x20(%rbp),%rcx
0xffffffff80f1322c <uma_vm_zone_stats+460>:     movslq -0x3c(%rbp),%rdx
0xffffffff80f13230 <uma_vm_zone_stats+464>:     shl    $0x6,%rdx
0xffffffff80f13234 <uma_vm_zone_stats+468>:     add    %rdx,%rcx
0xffffffff80f13237 <uma_vm_zone_stats+471>:     add    0x10(%rcx),%rax
0xffffffff80f1323b <uma_vm_zone_stats+475>:     mov    %rax,0x10(%rcx)
0xffffffff80f1323f <uma_vm_zone_stats+479>:     mov    -0x38(%rbp),%rax
0xffffffff80f13243 <uma_vm_zone_stats+483>:     cmpq   $0x0,(%rax)
0xffffffff80f13247 <uma_vm_zone_stats+487>:     je     0xffffffff80f13270 <uma_vm_zone_stats+528>
0xffffffff80f1324d <uma_vm_zone_stats+493>:     mov    -0x38(%rbp),%rax
0xffffffff80f13251 <uma_vm_zone_stats+497>:     mov    (%rax),%rax
0xffffffff80f13254 <uma_vm_zone_stats+500>:     movswq 0x10(%rax),%rax
0xffffffff80f13259 <uma_vm_zone_stats+505>:     mov    -0x20(%rbp),%rcx
0xffffffff80f1325d <uma_vm_zone_stats+509>:     movslq -0x3c(%rbp),%rdx
0xffffffff80f13261 <uma_vm_zone_stats+513>:     shl    $0x6,%rdx
0xffffffff80f13265 <uma_vm_zone_stats+517>:     add    %rdx,%rcx
0xffffffff80f13268 <uma_vm_zone_stats+520>:     add    0x10(%rcx),%rax
0xffffffff80f1326c <uma_vm_zone_stats+524>:     mov    %rax,0x10(%rcx)
0xffffffff80f13270 <uma_vm_zone_stats+528>:     mov    -0x38(%rbp),%rax
0xffffffff80f13274 <uma_vm_zone_stats+532>:     cmpq   $0x0,0x10(%rax)
0xffffffff80f13279 <uma_vm_zone_stats+537>:     je     0xffffffff80f132a3 <uma_vm_zone_stats+579>
0xffffffff80f1327f <uma_vm_zone_stats+543>:     mov    -0x38(%rbp),%rax
0xffffffff80f13283 <uma_vm_zone_stats+547>:     mov    0x10(%rax),%rax
0xffffffff80f13287 <uma_vm_zone_stats+551>:     movswq 0x10(%rax),%rax
0xffffffff80f1328c <uma_vm_zone_stats+556>:     mov    -0x20(%rbp),%rcx
0xffffffff80f13290 <uma_vm_zone_stats+560>:     movslq -0x3c(%rbp),%rdx
0xffffffff80f13294 <uma_vm_zone_stats+564>:     shl    $0x6,%rdx
0xffffffff80f13298 <uma_vm_zone_stats+568>:     add    %rdx,%rcx
0xffffffff80f1329b <uma_vm_zone_stats+571>:     add    0x10(%rcx),%rax
0xffffffff80f1329f <uma_vm_zone_stats+575>:     mov    %rax,0x10(%rcx)
0xffffffff80f132a3 <uma_vm_zone_stats+579>:     mov    -0x38(%rbp),%rax
0xffffffff80f132a7 <uma_vm_zone_stats+583>:     mov    0x18(%rax),%rax
0xffffffff80f132ab <uma_vm_zone_stats+587>:     mov    -0x20(%rbp),%rcx
0xffffffff80f132af <uma_vm_zone_stats+591>:     movslq -0x3c(%rbp),%rdx
0xffffffff80f132b3 <uma_vm_zone_stats+595>:     shl    $0x6,%rdx
0xffffffff80f132b7 <uma_vm_zone_stats+599>:     add    %rdx,%rcx
0xffffffff80f132ba <uma_vm_zone_stats+602>:     mov    %rax,(%rcx)
0xffffffff80f132bd <uma_vm_zone_stats+605>:     mov    -0x38(%rbp),%rax
0xffffffff80f132c1 <uma_vm_zone_stats+609>:     mov    0x20(%rax),%rax
0xffffffff80f132c5 <uma_vm_zone_stats+613>:     mov    -0x20(%rbp),%rcx
0xffffffff80f132c9 <uma_vm_zone_stats+617>:     movslq -0x3c(%rbp),%rdx
0xffffffff80f132cd <uma_vm_zone_stats+621>:     shl    $0x6,%rdx
0xffffffff80f132d1 <uma_vm_zone_stats+625>:     add    %rdx,%rcx
0xffffffff80f132d4 <uma_vm_zone_stats+628>:     mov    %rax,0x8(%rcx)
0xffffffff80f132d8 <uma_vm_zone_stats+632>:     mov    -0x3c(%rbp),%eax
0xffffffff80f132db <uma_vm_zone_stats+635>:     add    $0x1,%eax
0xffffffff80f132de <uma_vm_zone_stats+638>:     mov    %eax,-0x3c(%rbp)
0xffffffff80f132e1 <uma_vm_zone_stats+641>:     jmpq   0xffffffff80f1314c <uma_vm_zone_stats+236>
0xffffffff80f132e6 <uma_vm_zone_stats+646>:     add    $0x40,%rsp
0xffffffff80f132ea <uma_vm_zone_stats+650>:     pop    %rbp
0xffffffff80f132eb <uma_vm_zone_stats+651>:     retq   
End of assembler dump.