[CI] Collect an MSBuild performance summary and binary log on request (#7378)

The Windows job spends about 28 minutes inside one "Build project"
group, with nothing in it that says where the time goes: MSBuild runs
single-node because no --parallel is passed, so projects build one
after another and it is not visible which projects, tasks or phases are
responsible.

Add a --profile flag that makes the Windows build write
-flp:PerformanceSummary and -bl, repeat the summary in the job log so
the numbers need no download, and report the core count, which decides
how much parallelism is worth asking for. The binary log is uploaded as
an artifact only on the runs that asked for it.

The workflow drives it from a build_profile matrix key that is empty by
default, so no build changes behaviour until someone sets it.

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

.ci/compile.sh

@@ -17,8 +17,9 @@
 # --dir <dir> sets the name of the build dir, default is "build"
 # --cmake-generator <generator> sets CMAKE_GENERATOR as used by cmake
 # --target-macos-version <version> sets the min os version - only used for macOS builds
-# uses env: BUILDTYPE MAKE_INSTALL MAKE_PACKAGE PACKAGE_TYPE PACKAGE_SUFFIX MAKE_SERVER MAKE_NO_CLIENT MAKE_TEST USE_CCACHE CCACHE_SIZE CCACHE_EVICTION_AGE BUILD_DIR CMAKE_GENERATOR TARGET_MACOS_VERSION MAKE_SANITIZE MAKE_COVERAGE VCPKG_TARGET_MACOS_VERSION
-# (correspond to args: --debug/--release --install --package <package type> --suffix <suffix> --server --test --sanitize --coverage --ccache <ccache_size> --dir <dir>)
+# --profile writes an MSBuild performance summary and binary log, Windows only
+# uses env: BUILDTYPE MAKE_INSTALL MAKE_PACKAGE PACKAGE_TYPE PACKAGE_SUFFIX MAKE_SERVER MAKE_NO_CLIENT MAKE_TEST USE_CCACHE CCACHE_SIZE CCACHE_EVICTION_AGE BUILD_DIR CMAKE_GENERATOR TARGET_MACOS_VERSION MAKE_SANITIZE MAKE_COVERAGE VCPKG_TARGET_MACOS_VERSION BUILD_PROFILE
+# (correspond to args: --debug/--release --install --package <package type> --suffix <suffix> --server --test --sanitize --coverage --ccache <ccache_size> --dir <dir> --profile)
 # exitcode: 1 for failure, 3 for invalid arguments
 
 # Read arguments
@@ -115,6 +116,10 @@ while [[ $# != 0 ]]; do
       export CMAKE_GENERATOR=$1
       shift
       ;;
+    '--profile')
+      BUILD_PROFILE=1
+      shift
+      ;;
     '--target-macos-version')
       shift
       if [[ $# == 0 ]]; then
@@ -209,6 +214,22 @@ function ccachestatsverbose() {
   fi
 }
 
+function cpuinfo() {
+  # The number of cores decides how much build parallelism is useful; the hosted
+  # runners are not all sized alike, so read it off the machine instead of assuming.
+  case "$RUNNER_OS" in
+  Windows)
+    echo "cores: ${NUMBER_OF_PROCESSORS:-unknown}"
+    ;;
+  macOS)
+    echo "cores: $(sysctl -n hw.ncpu)"
+    ;;
+  *)
+    echo "cores: $(nproc 2>/dev/null || echo unknown)"
+    ;;
+  esac
+}
+
 # Compile
 if [[ $RUNNER_OS == macOS ]]; then
   # QTDIR is needed for macOS since we actually only use the cached thin Qt binaries instead of the install-qt-action,
@@ -296,6 +317,13 @@ elif [[ $RUNNER_OS == Windows ]]; then
   # Enable MTT, see https://devblogs.microsoft.com/cppblog/improved-parallelism-in-msbuild/
   # and https://devblogs.microsoft.com/cppblog/cpp-build-throughput-investigation-and-tune-up/#multitooltask-mtt
   buildflags+=(-- -p:UseMultiToolTask=true -p:EnableClServerMode=true)
+  if [[ $BUILD_PROFILE ]]; then
+    # A performance summary says which projects and tasks cost what, the binary log
+    # keeps the full timeline; both are far too noisy to always produce. The files
+    # land next to the solution, i.e. in the build dir the workflow uploads. These
+    # join the MTT options above, which already carried the "--" separator.
+    buildflags+=("-flp:PerformanceSummary;v=q;LogFile=msbuild-perf.log" -bl:msbuild.binlog)
+  fi
 fi
 
 if [[ $USE_CCACHE ]]; then
@@ -311,10 +339,19 @@ cmake .. "${flags[@]}"
 echo "::endgroup::"
 
 echo "::group::Build project"
+cpuinfo
 echo "Running cmake --build with flags: ${buildflags[*]}"
 cmake --build . "${buildflags[@]}"
 echo "::endgroup::"
 
+if [[ $BUILD_PROFILE && $RUNNER_OS == Windows && -f msbuild-perf.log ]]; then
+  # Repeat the summary in the job log so the numbers are readable without
+  # downloading the binary log, which is hundreds of megabytes.
+  echo "::group::MSBuild performance summary"
+  cat msbuild-perf.log
+  echo "::endgroup::"
+fi
+
 if [[ $USE_CCACHE ]]; then
   if [[ $CCACHE_EVICTION_AGE ]]; then
     echo "::group::evict ccache files older than $CCACHE_EVICTION_AGE"

.github/workflows/desktop-build.yml

@@ -385,6 +385,10 @@ jobs:
             target: 10
             runner: windows-2025    # https://github.com/actions/runner-images/blob/main/images/windows/Windows2025-VS2026-Readme.md
 
+            # Set build_profile: 1 to have the build write an MSBuild performance
+            # summary and a binary log; empty on every entry that runs by default.
+            build_profile: ''
+
             cmake_generator: "Visual Studio 18 2026"
             cmake_generator_platform: x64
             make_package: 1
@@ -400,6 +404,7 @@ jobs:
     runs-on: ${{ matrix.runner }}
     timeout-minutes: 100
     env:
+      BUILD_PROFILE: '${{ matrix.build_profile }}'
       CCACHE_DIR: ${{ github.workspace }}/.cache/
       CCACHE_SIZE: 600M    # space of all repo is 10Gi: https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#usage-limits-and-eviction-policy
 
@@ -701,6 +706,17 @@ jobs:
             build/oracle/Release/*.pdb
             build/servatrice/Release/*.pdb
 
+      # Written only when the matrix entry sets build_profile, so the artifact
+      # exists exactly on the runs that were asked to produce one.
+      - name: "[Windows] Upload MSBuild binary log"
+        if: always() && matrix.os == 'Windows' && env.BUILD_PROFILE == '1'
+        uses: actions/upload-artifact@v7
+        with:
+          if-no-files-found: error
+          name: ${{ steps.build.outputs.name }}-msbuild
+          path: build/msbuild.binlog
+          retention-days: 7
+
       - name: "Upload to release"
         if: needs.configure.outputs.tag != null && matrix.make_package == '1'
         id: upload_release