No D compiler currently targets Windows for X86-64, but LLVM has the ability to generate code for this OS/architecture combination. This ticket is a request/progress log of getting LLVMDC to generate code for 64-bit Windows.
The included patch is a work-in-progress which should allow LLVMDC to compile using Microsoft Visual Studio 2008 and LLVM SVN 56998 (also compiled for x64|Debug using MSVC9). It will compile in 32 or 64 bit modes to generate .bc files. The runtime is not yet compiling (perhaps some MSBuild scripts are in order, as well as any needed changes to the runtime).
I am currently working on this and this ticket was created simply to record my progress in this area and upload the patch. Some of the code changes were needed to get MSVC to compile it, but shouldn't break anything. There may be problems with the MSVC build; it has not been thoroughly tested.