round-robin.sh: Optimize splitting builds to narrow regression

... down to a component.  E.g., in tcwg_bmk-gnu-* builds we track
binutils, gcc and glibc, but most regressions happen due to gcc
changes.  Therefore instead of splitting binutils+gcc+glibc build
into builds for binutils, gcc and glibc it is better to trigger
binutils+glibc and gcc builds.  If the regression does occur in
binutils+glibc build, then it will be split into binutils and glibc
builds.

Change-Id: Ifd2effea69fe17b3271645f9a6c1e482cb79ceac

1 files changed, 26 insertions, 0 deletions

diff --git a/tcwg_bmk-build.sh b/tcwg_bmk-build.sh
index 82a29980..795dc9c4 100755
--- a/tcwg_bmk-build.sh
+++ b/tcwg_bmk-build.sh
@@ -383,6 +383,32 @@ no_regression_to_base_p ()
     )
 }
 
+# Implement rr[breakup_updated_components] hook.
+tcwg_bmk_breakup_updated_components ()
+{
+    (
+    set -euf -o pipefail
+
+    # Compiler changes tend to cause the most regressions.
+    # Breakup updated components into compiler and the rest of components
+    # to reduce the number of builds.
+    local cc
+    case "${rr[toolchain]}" in
+	llvm) cc="llvm" ;;
+	gnu) cc="gcc" ;;
+	*) assert false ;;
+    esac
+
+    if print_updated_components "\n" | grep -q "^$cc\$"; then
+	echo "$cc"
+	print_updated_components "\n" | grep -v "^$cc\$" | tr '\n' ' '
+    else
+	print_updated_components "\n"
+    fi
+    )
+}
+rr[breakup_updated_components]=tcwg_bmk_breakup_updated_components
+
 run_step stop_on_fail -10 reset_artifacts
 run_step stop_on_fail x prepare_abe
 run_step skip_on_fail -9 build_abe binutils