github: Build two linux toolchains, one with and one without assertions, in scheduled builds

Use the one without assertions for cross-building toolchains, as the
one with assertions is too slow. In practice, one or more of the cross
toolchain builds end up timing out (exceeding the 6 h limit) almost
every day in the scheduled builds, requiring reruns (sometimes
multiple reruns) to complete successfully in time.

(There seems to be a big variation in what actual runner the jobs
end up using; some runners complete the cross builds in around 4 h,
while some are much slower, and seem to require 5-6 hours or more.)

In practice, during the 2 months that I've had scheduled jobs
running on Github Actions, there haven't been any failed asserts
triggered and caught in the cross builds (but once in the cross builds
of ffmpeg, which still keep using a toolchain with asserts enabled).

.github/workflows/build.yml

@@ -33,12 +33,6 @@ jobs:
           retention-days: 7
 
   # Build a cross compiler for Linux, targeting Windows.
-  #
-  # The scheduled builds are made with the latest git version of llvm-project
-  # and mingw-w64. When using random git snapshot builds of llvm, there's
-  # always a risk for bugs - thus build such versions with assertions enabled,
-  # to better catch such bugs early. This makes the first-stage toolchain built
-  # here in scheduled builds somewhat slower.
   linux:
     if: (github.event_name != 'schedule') || (github.repository == 'mstorsjo/llvm-mingw')
     needs: [get-versions]
@@ -55,13 +49,12 @@ jobs:
           . versions
           echo Building llvm-project $LLVM_VERSION mingw-w64 $MINGW_W64_VERSION, with assertions enabled
           cat versions >> $GITHUB_ENV
-          echo ASSERT_PARAMS=--enable-asserts >> $GITHUB_ENV
           mkdir -p install/llvm-mingw
           cp versions install/llvm-mingw
       - name: Build
         run: |
           sudo apt-get update && sudo apt-get install ninja-build
-          ./build-all.sh $(pwd)/install/llvm-mingw --disable-clang-tools-extra --disable-lldb $ASSERT_PARAMS
+          ./build-all.sh $(pwd)/install/llvm-mingw --disable-clang-tools-extra --disable-lldb
           cd install
           tar -Jcf ../llvm-mingw-linux.tar.xz llvm-mingw
       - uses: actions/upload-artifact@v2
@@ -71,6 +64,44 @@ jobs:
             llvm-mingw-linux.tar.xz
           retention-days: 7
 
+  # Build a cross compiler for Linux, targeting Windows, with assertions enabled.
+  #
+  # The scheduled builds are made with the latest git version of llvm-project
+  # and mingw-w64. When using random git snapshot builds of llvm, there's
+  # always a risk for bugs - thus build such versions with assertions enabled,
+  # to better catch such bugs early. This makes the first-stage toolchain built
+  # here in scheduled builds somewhat slower.
+  linux-asserts:
+    if: (github.event_name == 'schedule') && (github.repository == 'mstorsjo/llvm-mingw')
+    needs: [get-versions]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/download-artifact@v3
+        if: github.event_name == 'schedule'
+        with:
+          name: versions
+      - name: Set build env vars
+        if: github.event_name == 'schedule'
+        run: |
+          . versions
+          echo Building llvm-project $LLVM_VERSION mingw-w64 $MINGW_W64_VERSION, with assertions enabled
+          cat versions >> $GITHUB_ENV
+          mkdir -p install/llvm-mingw
+          cp versions install/llvm-mingw
+      - name: Build
+        run: |
+          sudo apt-get update && sudo apt-get install ninja-build
+          ./build-all.sh $(pwd)/install/llvm-mingw --disable-clang-tools-extra --disable-lldb --enable-asserts
+          cd install
+          tar -Jcf ../llvm-mingw-linux.tar.xz llvm-mingw
+      - uses: actions/upload-artifact@v2
+        with:
+          name: linux-asserts-toolchain
+          path: |
+            llvm-mingw-linux.tar.xz
+          retention-days: 7
+
   # Build a cross compiler for macOS, targeting Windows.
   macos:
     if: (github.event_name != 'schedule') || (github.repository == 'mstorsjo/llvm-mingw')
@@ -153,11 +184,6 @@ jobs:
   # Use the Linux cross compilers built in the first step to cross compile
   # llvm and make a proper standalone toolchain for Windows (for all 4
   # architectures). The binaries built here match actual releases quite closely.
-  #
-  # For scheduled builds, the first stage compiler was built with assertions
-  # enabled, but this stage is built without assertions - so the end packaged
-  # build should be as fast as normal releases (with the intent that the first
-  # stage compiler should build enough code to find many regressions).
   linux-cross:
     if: (github.event_name != 'schedule') || (github.repository == 'mstorsjo/llvm-mingw')
     needs: [linux]
@@ -231,11 +257,12 @@ jobs:
           ./run-tests.sh /llvm-mingw
 
   # Test cross-building ffmpeg for all 4 targeted architectures from linux.
-  # This is done only on scheduled builds, to give them a bit more testing,
-  # to find potential code generation regressions that trigger failed asserts.
+  # This is done only on scheduled builds, with a toolchain with assertions
+  # enabled, to catch code generation bugs that might trigger asserts, to
+  # find such regressions early.
   linux-test-cross-build-ffmpeg:
     if: (github.event_name == 'schedule') && (github.repository == 'mstorsjo/llvm-mingw')
-    needs: [linux]
+    needs: [linux-asserts]
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -248,7 +275,7 @@ jobs:
     steps:
       - uses: actions/download-artifact@v3
         with:
-          name: linux-toolchain
+          name: linux-asserts-toolchain
       - name: Unpack cross toolchain
         run: |
           tar -Jxf llvm-mingw-linux.tar.xz