Nim binary size from 160 KB to 150 Bytes

Accompanying blog article

Uses the nim-syscall library.

x86-64

Results from the article, on Linux x86-64 with GCC 5.1 and Clang 3.6.0:

$ nimble install syscall

$ ./run.sh
== Using the C Standard Library ==
hello_unoptimized    163827
hello_release         62131
hello_optsize         25248
hello_optsize_strip   18552
hello_gcnone          10344
hello_standalone       6208

== Disregarding the C Standard Library ==
hello2                 1776
hello3                  952

== Custom Linking ==
hello3_custom           158
hello4_custom           150
hello5_custom           149

$ objdump -rd nimcache/hello5.o
...
0000000000000000 <_start>:
 0: b8 01 00 00 00          mov    $0x1,%eax
 5: ba 07 00 00 00          mov    $0x7,%edx
 a: be 08 00 40 00          mov    $0x400008,%esi
 f: 48 89 c7                mov    %rax,%rdi
12: 0f 05                   syscall 
14: 31 ff                   xor    %edi,%edi
16: b8 3c 00 00 00          mov    $0x3c,%eax
1b: 0f 05                   syscall 
...

$ ./run.sh --cc:clang
== Using the C Standard Library ==
hello_unoptimized    171989
hello_release         33435
hello_optsize         29339
hello_optsize_strip   22704
hello_gcnone          10400
hello_standalone       6248

== Disregarding the C Standard Library ==
hello2                 1840
hello3                  952

== Custom Linking ==
hello3_custom           160
hello4_custom           152
hello5_custom           151

x86

Works on 32bit x86 now, also with GCC 5.1 and Clang 3.6.0:

$ ./run32.sh
== Using the C Standard Library ==
hello_unoptimized    147301
hello_release         60001
hello_optsize         23127
hello_optsize_strip   17836
hello_gcnone           9636
hello_standalone       5520

== Disregarding the C Standard Library ==
hello2                 1488
hello3                  696

== Custom Linking ==
hello3_custom           127
hello4_custom           119
hello5_custom           116

$ ./run32.sh --cc:clang
== Using the C Standard Library ==
hello_unoptimized    143221
hello_release         27261
hello_optsize         23165
hello_optsize_strip   17888
hello_gcnone           9688
hello_standalone       5564

== Disregarding the C Standard Library ==
hello2                  832
hello3                  484

== Custom Linking ==
hello3_custom           126
hello4_custom           118
hello5_custom           116

$ objdump -rd nimcache/hello5.o
...
00000000 <_start>:
   0:	53                   	push   %ebx
   1:	b8 04 00 00 00       	mov    $0x4,%eax
   6:	bb 01 00 00 00       	mov    $0x1,%ebx
   b:	b9 08 00 40 00       	mov    $0x400008,%ecx
  10:	ba 07 00 00 00       	mov    $0x7,%edx
  15:	cd 80                	int    $0x80
  17:	b8 01 00 00 00       	mov    $0x1,%eax
  1c:	31 db                	xor    %ebx,%ebx
  1e:	cd 80                	int    $0x80
...