Update build instructions for WoA (use LLVM19 and its flang-new)

Author: martin-frbg

docs/install.md

@@ -439,49 +439,34 @@ To then use the built OpenBLAS shared library in Visual Studio:
 
 #### Windows on Arm
 
+While OpenBLAS can be built with Microsoft VisualStudio (Community Edition or commercial), you would only be able to build for the GENERIC target
+that does not use optimized assembly kernels, also the stock VisualStudio lacks the Fortran compiler necessary for building the LAPACK component.
+It is therefore highly recommended to download the free LLVM compiler suite and use it to compile OpenBLAS outside of VisualStudio.
+
 The following tools needs to be installed to build for Windows on Arm (WoA):
 
--   Clang for Windows on Arm.
-    Find the latest LLVM build for WoA from [LLVM release page](https://releases.llvm.org/).
-    E.g: LLVM 12 build for WoA64 can be found [here](https://github.com/llvm/llvm-project/releases/download/llvmorg-12.0.0/LLVM-12.0.0-woa64.exe)
-    Run the LLVM installer and ensure that LLVM is added to environment PATH.
--   Download and install classic Flang for Windows on Arm.
-    Classic Flang is the only available Fortran compiler for Windows on Arm for now.
-    A pre-release build can be found [here](https://github.com/kaadam/flang/releases/tag/v0.1)
-    There is no installer for classic flang and the zip package can be
-    extracted and the path needs to be added to environment `PATH`.
-    E.g., in PowerShell:
-    ```
-    $env:Path += ";C:\flang_woa\bin"
-    ```
+-   LLVM for Windows on Arm.
+    Find the latest LLVM build for WoA from [LLVM release page](https://releases.llvm.org/) - you want the package whose name ends in "woa64.exe".
+    E.g: LLVM 19 build for WoA64 can be found [here](https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.4/LLVM-19.1.4-woa64.exe)
+    Run the LLVM installer and ensure that LLVM is added to environment PATH. (If you do not want to add it to the PATH, you will need to specify
+    both C and Fortran compiler to Make or CMake with their full path later on)
 
-The following steps describe how to build the static library for OpenBLAS with and without LAPACK:
+The following steps describe how to build the static library for OpenBLAS with either Make or CMake:
 
-1.  Build OpenBLAS static library with BLAS and LAPACK routines with Make:
+1.  Build OpenBLAS with Make:
 
     ```bash
-    $ make CC="clang-cl" HOSTCC="clang-cl" AR="llvm-ar" BUILD_WITHOUT_LAPACK=0 NOFORTRAN=0 DYNAMIC_ARCH=0 TARGET=ARMV8 ARCH=arm64 BINARY=64 USE_OPENMP=0 PARALLEL=1 RANLIB="llvm-ranlib" MAKE=make F_COMPILER=FLANG FC=FLANG FFLAGS_NOOPT="-march=armv8-a -cpp" FFLAGS="-march=armv8-a -cpp" NEED_PIC=0 HOSTARCH=arm64 libs netlib
+    $ make CC=clang-cl FC=flang-new AR="llvm-ar" TARGET=ARMV8 ARCH=arm64 RANLIB="llvm-ranlib" MAKE=make
     ```
 
-2.  Build static library with BLAS routines using CMake:
-
-    Classic Flang has compatibility issues with CMake, hence only BLAS routines can be compiled with CMake:
-
+2. Build OpenBLAS with CMake
     ```bash
     $ mkdir build
     $ cd build
-    $ cmake ..  -G Ninja -DCMAKE_C_COMPILER=clang -DBUILD_WITHOUT_LAPACK=1 -DNOFORTRAN=1 -DDYNAMIC_ARCH=0 -DTARGET=ARMV8 -DARCH=arm64 -DBINARY=64 -DUSE_OPENMP=0 -DCMAKE_SYSTEM_PROCESSOR=ARM64 -DCMAKE_CROSSCOMPILING=1 -DCMAKE_SYSTEM_NAME=Windows
-    $ cmake --build . --config Release
+    $ cmake .. -G Ninja -DCMAKE_C_COMPILER=clang-cl -DCMAKE_Fortran_COMPILER=flang-new -DTARGET=ARMV8 -DCMAKE_BUILD_TYPE=Release
+    $ cmake --build .
     ```
 
-!!! tip "`getarch.exe` execution error"
-
-    If you notice that platform-specific headers by `getarch.exe` are not
-    generated correctly, this could be due to a known debug runtime DLL issue for
-    arm64 platforms. Please check out [this page](https://linaro.atlassian.net/wiki/spaces/WOAR/pages/28677636097/Debug+run-time+DLL+issue#Workaround)
-    for a workaround.
-
-
 #### Generating an import library
 
 Microsoft Windows has this thing called "import libraries". You need it for