[DOCS] Improve windows build instruction via conda (apache#6944)

cmake/config.cmake

@@ -113,15 +113,16 @@ set(USE_MICRO_STANDALONE_RUNTIME OFF)
 #
 # Possible values:
 # - ON: enable llvm with cmake's find search
-# - OFF: disable llvm
+# - OFF: disable llvm, note this will disable CPU codegen
+#        which is needed for most cases
 # - /path/to/llvm-config: enable specific LLVM when multiple llvm-dev is available.
-set(USE_LLVM OFF)
+set(USE_LLVM ON)
 
 #---------------------------------------------
 # Contrib libraries
 #---------------------------------------------
 # Whether to build with BYODT software emulated posit custom datatype
-# 
+#
 # Possible values:
 # - ON: enable BYODT posit, requires setting UNIVERSAL_PATH
 # - OFF: disable BYODT posit
@@ -234,7 +235,7 @@ set(USE_TENSORRT_RUNTIME OFF)
 
 # Whether use VITIS-AI codegen
 set(USE_VITIS_AI OFF)
- 
+
 # Build ANTLR parser for Relay text format
 # Possible values:
 # - ON: enable ANTLR by searching default locations (cmake find_program for antlr4 and /usr/local for jar)

conda/build-environment.yaml

@@ -15,13 +15,15 @@
 # specific language governing permissions and limitations
 # under the License.
 
-# Build environment.
+# Build environment that can be used to build tvm.
 name: tvm-build
 
+# The conda channels to lookup the dependencies
 channels:
   - anaconda
   - conda-forge
 
+# The packages to install to the environment
 dependencies:
   - conda-build
   - git

docs/install/from_source.rst

@@ -90,7 +90,7 @@ The configuration of TVM can be modified by `config.cmake`.
     you want to build for (OpenCL, RCOM, METAL, VULKAN, ...).
   - To help with debugging, ensure the embedded graph runtime and debugging functions are enabled with ``set(USE_GRAPH_RUNTIME ON)`` and ``set(USE_GRAPH_RUNTIME_DEBUG ON)``
 
-- TVM optionally depends on LLVM. LLVM is required for CPU codegen that needs LLVM.
+- TVM requires LLVM for for CPU codegen. We highly recommend you to build with the LLVM support on.
 
   - LLVM 4.0 or higher is needed for build with LLVM. Note that version of LLVM from default apt may lower than 4.0.
   - Since LLVM takes long time to build from source, you can download pre-built version of LLVM from
@@ -102,7 +102,7 @@ The configuration of TVM can be modified by `config.cmake`.
   - You can also use `LLVM Nightly Ubuntu Build <https://apt.llvm.org/>`_
 
     - Note that apt-package append ``llvm-config`` with version number.
-      For example, set ``set(LLVM_CONFIG llvm-config-4.0)`` if you installed 4.0 package
+      For example, set ``set(USE_LLVM llvm-config-10)`` if you installed LLVM 10 package
 
 - We can then build tvm and related libraries.
 
@@ -122,27 +122,58 @@ The configuration of TVM can be modified by `config.cmake`.
 
 If everything goes well, we can go to :ref:`python-package-installation`
 
+.. _build-with-conda:
+
+Building with a Conda Environment
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Conda is a very handy way to the necessary obtain dependencies needed for running TVM.
+First, follow the `conda's installation guide <https://docs.conda.io/projects/conda/en/latest/user-guide/install/>`_
+to install miniconda or anaconda if you do not yet have conda in your system. Run the following command in a conda environment:
+
+.. code:: bash
+
+    # Create a conda environment with the dependencies specified by the yaml
+    conda env create --file conda/build-environment.yaml
+    # Activate the created environment
+    conda activate tvm-build
+
+The above command will install all necessary build dependencies such as cmake and LLVM. You can then run the standard build process in the last section.
+
+If you want to use the compiled binary outside the conda environment,
+you can set LLVM to static linking mode ``set(USE_LLVM "llvm-config --link-static")``.
+In this way, the resulting library won't depend on the dynamic LLVM libraries in the conda environment.
+
+The above instructions show how to use conda to provide the necessary build dependencies to build libtvm.
+If you are already using conda as your package manager and wish to directly build and install tvm as a conda package, you can follow the instructions below:
+
+.. code:: bash
+
+   conda build --output-folder=conda/pkg  conda/recipe
+   # Run conda/build_cuda.sh to build with cuda enabled
+   conda install tvm -c ./conda/pkg
+
 Building on Windows
 ~~~~~~~~~~~~~~~~~~~
-
-TVM support build via MSVC using cmake. The minimum required VS version is **Visual Studio Community 2015 Update 3**.
-In order to generate the VS solution file using cmake, make sure you have a recent version of cmake added to your path and then from the TVM directory:
+TVM support build via MSVC using cmake. You will need to ontain a visual studio compiler.
+The minimum required VS version is **Visual Studio Community 2015 Update 3**.
+We recommend following :ref:`build-with-conda` to obtain necessary dependencies and
+get an activated tvm-build environment. Then you can run the following command to build
 
 .. code:: bash
 
-  mkdir build
-  cd build
-  cmake -G "Visual Studio 14 2015 Win64" -DCMAKE_BUILD_TYPE=Release -DCMAKE_CONFIGURATION_TYPES="Release" ..
+    mkdir build
+    cd build
+    cmake -A x64 -Thost=x64 ..
+    cd ..
 
-Starting with Visual Studio 2019 the architecture is specified differently so use this command
+The above command generates the solution file under the build directory.
+You can then run the following command to build
 
 .. code:: bash
 
-  cmake -G "Visual Studio 16 2019" -A x64 -DCMAKE_BUILD_TYPE=Release -DCMAKE_CONFIGURATION_TYPES="Release" ..
+    cmake --build build --config Release -- /m
 
-This will generate the VS project using the MSVC 64 bit generator.
-Open the .sln file in the build directory and build with Visual Studio.
-In order to build with LLVM in windows, you will need to build LLVM from source.
 
 Building ROCm support
 ~~~~~~~~~~~~~~~~~~~~~