## Building Graal

There is a Python script in mxtool/mx.py that simplifies working with the code
base. It requires Python 2.7. While you can run this script by using an absolute path,
it's more convenient to add graal/mxtool to your PATH environment variable so that the
'mx' helper script can be used. The following instructions in this file assume this
setup.

Building both the Java and C++ source code comprising the Graal VM
can be done with the following simple command.

```
% mx build
```

There are a number of VM configurations supported by mx which can
be explicitly specified using the --vm option. However, you'll typically
want one of these VM configurations:

1. The 'server' configuration is a standard HotSpot VM that includes the
   runtime support for Graal but uses the existing compilers for normal
   compilation (e.g., when the interpreter threshold is hit for a method).
   Compilation with Graal is only done by explicit requests to the
   Graal API. This is how Truffle uses Graal.
   
2. The 'graal' configuration is a VM where normal compilations are performed
   by Graal. By default tiered compilation is enabled and Graal will be used at
   the last tier while C1 will be used for the first compiled tiers.

Unless you use the --vm option with the build command, you will be presented
with a dialogue to choose one of the above VM configurations for the build
as well as have the option to make it your default for subsequent commands
that need a VM specified.

To build the debug or fastdebug builds:

```
% mx --vmbuild debug build
% mx --vmbuild fastdebug build
```

## Running Graal

To run the VM, use 'mx vm' in place of the standard 'java' command:

```
% mx vm ...
```

To select the fastdebug or debug builds of the VM:

```
% mx --vmbuild fastdebug vm ...
% mx --vmbuild debug vm ...
```

## Other VM Configurations

In addition to the VM configurations described above, there are
VM configurations that omit all VM support for Graal:

```
% mx --vm server-nograal build
% mx --vm server-nograal vm -version
java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b25)
OpenJDK 64-Bit Server VM (build 25.40-b25-internal, mixed mode)

```

```
% mx --vm client-nograal build
% mx --vm client-nograal vm -version
java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b25)
OpenJDK 64-Bit Client VM (build 25.40-b25-internal, mixed mode)
```

These configurations aim to match as closely as possible the
VM(s) included in the OpenJDK binaries one can download.