GDC should build for MINGW and MINGW64 targets, however not much testing has been done.
The following patches are required for binutils / gcc to fix TLS support:
- https://github.com/venix1/MinGW-GDC/blob/master/patches/mingw-tls-binutils-2.23.1.patch
- https://github.com/venix1/MinGW-GDC/blob/master/patches/mingw-tls-gcc-4.8.patch
This patch is required to fix a bug in GCC buildscripts:
SEH should work for 64 bit windows targets.