Not sure if this is still sometimes necessary when using DMD with other compilers or libraries. But these here looks very promising:

http://www.agner.org/optimize/

Object file converter
This utility can be used for converting object files between COFF/PE, OMF, ELF and Mach-O formats for all 32-bit and 64-bit x86 platforms. Can modify symbol names in object files. Can build, modify and convert function libraries across platforms. Can dump object files and executable files. Also includes a very good disassembler supporting the SSE4, AVX, AVX2, AVX512, FMA3, FMA4, XOP and Knights Corner instruction sets. Source code included (GPL).

-- 
Robert M. Münch
http://www.saphirion.com
smarter | better | faster