% cat wat.s
bits 64
default rel

section .data

yin:   dw 0x1337
yang:  dw 0x2600
foo:   dw 0x0420
.bar:  dw 0x1313
.baz:  dw 0xCAFE
.quux: dw 0xBEEF
blah:  dw 0xAA55

section .text

global start
start:
  mov ax,[yin]
  mov ax,[yang]
  mov ax,[foo]
  mov ax,[foo.bar]
  mov ax,[foo.baz]
  mov ax,[foo.quux]
  mov ax,[blah]
  lea rax,[start]
  mov rax,0x2000001
  mov rdi,0
  syscall

% yasm -f macho64 wat.s && otool -rv wat.o
wat.o:
Relocation information (__TEXT,__text) 7 entries
address  pcrel length extern type    scattered symbolnum/value
00000003 True  long   True   SIGNED  False     yin
0000000a True  long   True   SIGNED  False     yang
00000011 True  long   True   SIGNED  False     foo
00000018 True  long   True   SIGNED  False     foo.bar
0000001f True  long   True   SIGNED  False     foo.baz
00000026 True  long   True   SIGNED  False     foo.quux
0000002d True  long   True   SIGNED  False     blah

% nasm -f macho64 wat.s && otool -rv wat.o # before
wat.o:
Relocation information (__TEXT,__text) 7 entries
address  pcrel length extern type    scattered symbolnum/value
0000002d True  long   True   BRANCH  False     blah
00000026 True  long   True   BRANCH  False     blah
0000001f True  long   True   BRANCH  False     blah
00000018 True  long   True   BRANCH  False     blah
00000011 True  long   True   BRANCH  False     blah
0000000a True  long   True   BRANCH  False     blah
00000003 True  long   True   BRANCH  False     blah

% nasm -f macho64 wat.s && otool -rv wat.o # after
wat.o:
Relocation information (__TEXT,__text) 7 entries
address  pcrel length extern type    scattered symbolnum/value
0000002d True  long   True   BRANCH  False     blah
00000026 True  long   True   BRANCH  False     foo.quux
0000001f True  long   True   BRANCH  False     foo.baz
00000018 True  long   True   BRANCH  False     foo.bar
00000011 True  long   True   BRANCH  False     foo
0000000a True  long   True   BRANCH  False     yang
00000003 True  long   True   BRANCH  False     yin

% ./autogen.sh
% make CFLAGS='[default CFLAGS except -O0 replaces -O2]' -j nasm

% lldb nasm # before
(lldb) b get_closest_section_symbol_by_offset
(lldb) run -f macho64 wat.s
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8589934592) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8589934594) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8589934596) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8589934598) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8589934600) + 18 at outmac64.c:302
(lldb) bt
  * frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8589934600) + 18 at outmac64.c:302
    frame #1: 0x000000010004ae4c nasm`add_reloc(sect=0x0000000100300650, section=4, pcrel=1, bytes=4, reloff=8589934600) + 684 at outmac64.c:450
    frame #2: 0x0000000100048791 nasm`macho_output(secto=2, data=0x00007fff5fbff300, type=OUT_REL4ADR, size=4, section=4, wrt=-1) + 1217 at outmac64.c:601
    frame #3: 0x000000010000d647 nasm`out(offset=31, segto=2, data=0x00007fff5fbff300, type=OUT_REL4ADR, size=4, segment=4, wrt=-1) + 375 at assemble.c:353
    frame #4: 0x0000000100010ffe nasm`gencode(segment=2, offset=31, bits=64, ins=0x00007fff5fbff6f0, temp=0x00000001000f5430, insn_end=35) + 6286 at assemble.c:1906
    frame #5: 0x000000010000d239 nasm`assemble(segment=2, offset=29, bits=64, cp=iflag_t at 0x00007fff5fbff4e8, instruction=0x00007fff5fbff6f0, output=0x0000000100120340, error=0x0000000100006ad0, listgen=0x0000000100120500) + 3129 at assemble.c:673
    frame #6: 0x0000000100004434 nasm`assemble_file(fname=0x0000000100120a30, depend_ptr=0x0000000000000000) + 9028 at nasm.c:1752
    frame #7: 0x00000001000011a1 nasm`main(argc=4, argv=0x00007fff5fbffa30) + 1537 at nasm.c:465

% lldb nasm # after
(lldb) b get_closest_section_symbol_by_offset
(lldb) run -f macho64 wat.s
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=0) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=2) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=4) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=6) + 18 at outmac64.c:302
    frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8) + 18 at outmac64.c:302
(lldb) bt
  * frame #0: 0x000000010004afb2 nasm`get_closest_section_symbol_by_offset(fileindex='\x02', offset=8) + 18 at outmac64.c:302
    frame #1: 0x000000010004ae4c nasm`add_reloc(sect=0x0000000100300650, section=4, pcrel=1, bytes=4, reloff=8) + 684 at outmac64.c:450
    frame #2: 0x0000000100048790 nasm`macho_output(secto=2, data=0x00007fff5fbff300, type=OUT_REL4ADR, size=4, section=4, wrt=-1) + 1216 at outmac64.c:601
    frame #3: 0x000000010000d647 nasm`out(offset=31, segto=2, data=0x00007fff5fbff300, type=OUT_REL4ADR, size=4, segment=4, wrt=-1) + 375 at assemble.c:353
    frame #4: 0x0000000100010ffe nasm`gencode(segment=2, offset=31, bits=64, ins=0x00007fff5fbff6f0, temp=0x00000001000f5430, insn_end=35) + 6286 at assemble.c:1906
    frame #5: 0x000000010000d239 nasm`assemble(segment=2, offset=29, bits=64, cp=iflag_t at 0x00007fff5fbff4e8, instruction=0x00007fff5fbff6f0, output=0x0000000100120340, error=0x0000000100006ad0, listgen=0x0000000100120500) + 3129 at assemble.c:673
    frame #6: 0x0000000100004434 nasm`assemble_file(fname=0x0000000100120a30, depend_ptr=0x0000000000000000) + 9028 at nasm.c:1752
    frame #7: 0x00000001000011a1 nasm`main(argc=4, argv=0x00007fff5fbffa30) + 1537 at nasm.c:465