Update installation.rst with Windows/HIP instructions (#2207)

Discussed on #2203

docs/installation.rst

@@ -191,6 +191,38 @@ In most cases, it is better to install `WSL
 the Linux instructions above.  The C code generated by the Futhark
 compiler should work on Windows, except for the ``multicore`` backend.
 
+Alternatively, you can use the C compiler that is installed with
+`w64devkit`_
+
+Using HIP
+~~~~~~~~~~~~~~~~~~~~
+
+*Note*: dependencies can sometimes move faster than this documentation.
+This Windows/HIP HowTo was written in Jan 2025 on a setup without WSL,
+using PowerShell, and after the installation of `w64devkit`_ via `scoop`_.
+
+If you wish to use ``futhark hip`` on windows, you must have the
+`ROCm/HIP SDK`_ installed on your system.
+The SDK installation will create a ``HIP_PATH`` environment variable on
+your system pointing to the installed SDK. It is advised to check that
+this variable has indeed been created.
+
+In order for ```futhark hip``` to work you need to setup 3 environment
+variables in your PowerShell::
+
+  # CPATH creation so that the compiler can find the HIP headers
+  $env:CPATH = $env:HIP_PATH + "include"
+  # LIBRARY_PATH creation so that the linker can find the HIP libraries
+  $env:LIBRARY_PATH = $env:HIP_PATH + "lib"
+  # PATH modification so that the compiled app can find the HIP DLLs at runtime
+  $env:PATH = $env:PATH + ";" + $env:HIP_PATH + "bin"
+
+
+.. _`ROCm/HIP SDK`: https://www.amd.com/fr/developer/resources/rocm-hub/hip-sdk.html
+.. _`w64devkit`: https://github.com/skeeto/w64devkit
+.. _`scoop` : https://scoop.sh/
+
+
 Futhark with Nix
 ----------------