chore: Update build docs

docs/BUILD.md

@@ -2,7 +2,7 @@
 
 ## Installing Rustup
 
-Building Wasmer from source requires [Rust](https://rustup.rs/) **1.67+**.
+Building Wasmer from source requires [Rust](https://rustup.rs/) **1.81+**.
 
 The easiest way to install Rust on your system is via Rustup. To get Rustup on Linux and macOS, you can run the following:
 
@@ -15,14 +15,31 @@ curl https://sh.rustup.rs -sSf | sh
 
 ## Installing Additional Dependencies
 
+### Linux 
+Linux is fully supported by Wasmer. WASI(x) is also fully supported. Users
+building from source can enable the LLVM backend following the instruction in
+the dedicated section below and installing LLVM version 18. To install it,
+refer to [LLVM's download
+page](https://github.com/llvm/llvm-project/releases/tag/llvmorg-18.1.7) or
+check your distro's package manager.
+
+
+### macOS
+macOS is fully supported by Wasmer. WASI(x) is also fully supported. Users
+building from source can enable the LLVM backend following the instruction in
+the dedicated section below and installing LLVM version 18. To install it on
+macOS, you can use [homebrew](https://brew.sh/): `brew install llvm@18`.
+
+
 ### Windows
 
-Windows is fully supported by Wasmer. WASI is also fully supported.
+Windows is fully supported by Wasmer. WASI(x) is also fully supported.
 
 1. Install [Visual Studio](https://visualstudio.microsoft.com/thank-you-downloading-visual-studio/?sku=Community&rel=15)
 2. Install [Rust for Windows](https://win.rustup.rs/)
 3. Install [Git for Windows](https://git-scm.com/download/win). Allow it to add `git.exe` to your PATH (default settings for the installer are fine).
-4. \(optional\) Install [LLVM 11.0](https://prereleases.llvm.org/win-snapshots/LLVM-11.0.0-2663a25f-win64.exe)
+4. \(optional\) Install [LLVM 18.0](https://github.com/llvm/llvm-project/releases/download/llvmorg-18.1.7/LLVM-18.1.7-win64.exe)
+
 
 ## Building the Wasmer Runtime
 
@@ -35,41 +52,53 @@ git clone https://github.com/wasmerio/wasmer.git
 cd wasmer
 ```
 
-Wasmer supports three different compilers at the moment:
+Wasmer supports six different backends at the moment: `singlepass`,
+`cranelift`, `LLVM`, `V8`, `wasmi` and `wamr`.
 
 ### Singlepass Compiler
 
-Build Wasmer:
+The Singlepass compiler works on Linux, Darwin and Windows systems on amd64
+platforms and on Linux and Darwin systems on aarch64 platforms. Currently, it
+doesn't work on `RISC-V` or `loongarch64`. On system in which it can be used it
+is enabled by default.
+
+You can build Wasmer by running this command in the root of the repo:
 
 ```text
 make build-wasmer
 ```
 
-**Note**: you should see this `Enabled Compilers: singlepass` in console. 
+**Note**: you should see `singlepass` appear in the `Enabled Compilers: ...` message in the console. 
 
-You may disable Singlepass compiler with `export ENABLE_SINGLEPASS=0`.
+You may disable the Singlepass backend with the `ENABLE_SINGLEPASS=0` environment
+variable, and force its enabling with `ENABLE_SINGLEPASS=1`.
 
 ### Cranelift Compiler
 
-The Cranelift compiler will work if you are on a X86 or ARM machine. It will be detected automatically, so you don't need to do anything to your system to enable it.
+The Cranelift compiler will work if you are on a X86 or ARM machine. On system
+in which it can be used it is enabled by default.
+
+You can build Wasmer by running this command in the root of the repo:
 
 ```text
 make build-wasmer
 ```
 
-**Note**: should see this as the first line in the console:  
-`Enabled Compilers: cranelift`
+**Note**: you should see `cranelift` appear in the `Enabled Compilers: ...` message in the console. 
 
-You may disable the Cranelift compiler with `export ENABLE_CRANELIFT=0`.
+You may disable the Cranelift backend with the `ENABLE_SINGLEPASS=0` environment
+variable, and force its enabling with `ENABLE_SINGLEPASS=1`.
 
 ### LLVM Compiler
 
-If you want support for the Wasmer LLVM compiler, then you will also need to ensure:
+If you want support for the Wasmer LLVM compiler, then you will also need to:
 
-* Ensure that LLVM 10.0.x > is installed on your system
+* Ensure that LLVM >=18.0.x  is installed on your system
   * You can refer to [LLVM install instructions](https://github.com/wasmerio/wasmer/tree/master/lib/compiler-llvm#requirements)
   * You can also [download and use a prebuilt LLVM binary](https://releases.llvm.org/download.html)
-* In case `llvm-config` is not accessible, set the correct environment variable for LLVM to access: For example, the environment variable for LLVM 11.0.x would be: `LLVM_SYS_110_PREFIX=/path/to/unpacked/llvm-11.0`
+* In case `llvm-config` is not accessible, set the correct environment variable
+  for LLVM to access: For example, the environment variable for LLVM 18.0.x
+  would be: `LLVM_SYS_180_PREFIX=/path/to/unpacked/llvm-18.0`
 
 And create a Wasmer release
 
@@ -82,6 +111,19 @@ make build-wasmer
 
 You may disable the LLVM compiler with `export ENABLE_LLVM=0`.
 
+### V8, wasmi and wamr 
+To enable any of these backends, you can set the according `ENABLE_<backend>=1`
+flag at build time. The build script itself will download the necessary
+libraries at build time.
+
+Note, however, that these backends are not supported on all the platforms that
+Wasmer can run on.
+
+For example, to have a Wasmer build with all three backends enabled you can run: 
+```text
+ENABLE_V8=1 ENABLE_WASMI=1 ENABLE_WAMR=1 make build-wasmer
+```
+
 ### All compilers
 
 Once you have LLVM and Rust, you can just run:

lib/compiler-llvm/README.md

@@ -23,20 +23,20 @@ to native speeds.
 ## Requirements
 
 The LLVM compiler requires a valid installation of LLVM in your system.
-It currently requires **LLVM 15**.
+It currently requires **LLVM 18**.
 
 
 You can install LLVM easily on your Debian-like system via this command:
 
 ```bash
 wget https://apt.llvm.org/llvm.sh -O /tmp/llvm.sh
-sudo bash /tmp/llvm.sh 15
+sudo bash /tmp/llvm.sh 18
 ```
 
 Or in macOS:
 
 ```bash
-brew install llvm@15
+brew install llvm@18
 ```
 
 Or via any of the [pre-built binaries that LLVM offers][llvm-pre-built].