Install Sail from binary in CI

This should be a lot faster. It also means the version is pinned properly which wasn't the case before.

I also recommended users to do the same in the README do they don't have to deal with OPAM.

.github/workflows/compile.yml

@@ -7,19 +7,17 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
     - name: Install packages
-      run: sudo apt install -y opam zlib1g-dev pkg-config libgmp-dev z3 device-tree-compiler
+      run: sudo apt install -y opam zlib1g-dev pkg-config libgmp-dev device-tree-compiler curl
     - name: Check out repository code
       uses: actions/checkout@HEAD
       with:
         submodules: true
     - name: Ensure pre-commit checks pass
       run: pip install pre-commit && pre-commit run --all-files --show-diff-on-failure --color=always
-    - name: Init opam
-      run: opam init --disable-sandboxing -y
-    - name: Install sail
-      run: opam install -y sail
+    - name: Install sail from binary
+      run: curl --location https://github.com/rems-project/sail/releases/download/0.18-linux-binary/sail.tar.gz | tar xvz - --directory=/usr/local
     - name: Build and test simulators
-      run: eval $(opam env) && test/run_tests.sh
+      run: test/run_tests.sh
     - name: Upload test results
       if: always()
       uses: actions/upload-artifact@v4

README.md

@@ -275,7 +275,7 @@ Getting started
 
 ### Building the model
 
-Install [Sail](https://github.com/rems-project/sail/) [using opam](https://github.com/rems-project/sail/blob/sail2/INSTALL.md) then:
+Install [Sail](https://github.com/rems-project/sail/). On Linux you can download a [binary release](https://github.com/rems-project/sail/releases) (strongly recommended), or you can install from source [using opam](https://github.com/rems-project/sail/blob/sail2/INSTALL.md). Then:
 
 ```
 $ make