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, 22 insertions, 9 deletions

diff --git a/round-robin.sh b/round-robin.sh
index 099d514b..0c6da0ed 100644
--- a/round-robin.sh
+++ b/round-robin.sh
@@ -49,6 +49,10 @@ declare -gA rr
 # 2 sets of results.
 rr[no_regression_p]=no_regression_p
 
+# Hook to break up updated component (see print_updated_components) into
+# smaller sets: print one set per line.  By default, breakup into singletons.
+rr[breakup_updated_components]=breakup_updated_components
+
 # Print round-robin components that are being updated in this build
 # (the ones using non-baseline branches).
 print_updated_components ()
@@ -67,6 +71,12 @@ print_updated_components ()
     )
 }
 
+# By default, print each component on its own line.
+breakup_updated_components ()
+{
+    print_updated_components "\n"
+}
+
 # Print the single round-robin component being updated in this build.
 # Print nothing if multiple components are being updated.
 print_single_updated_component ()
@@ -480,17 +490,20 @@ check_regression ()
 	local single_component=$(print_single_updated_component)
 
 	if [ x"$single_component" = x"" -o x"${rr[mode]}" = x"bisect" ]; then
-	    local c
-	    for c in $(print_updated_components); do
-		local c2
-		for c2 in ${rr[components]}; do
-		    if [ x"$c" = x"$c2" ]; then
-			echo "${c2}_branch=${rr[${c}_branch]}"
+	    local -a update_components
+
+	    while read -a update_components; do
+		local c update_components2
+		update_components2=$(echo "${update_components[@]}" | tr ' ' '-')
+
+		for c in ${rr[components]}; do
+		    if echo "${update_components[@]}" | tr ' ' '\n' | grep -q "^$c\$"; then
+			echo "${c}_branch=${rr[${c}_branch]}"
 		    else
-			echo "${c2}_branch=baseline"
+			echo "${c}_branch=baseline"
 		    fi
-		done >> ${rr[top_artifacts]}/trigger-build-$c
-	    done
+		done > ${rr[top_artifacts]}/trigger-build-$update_components2
+	    done < <(${rr[breakup_updated_components]})
 	elif ! [ $score -lt -1 ] 2>/dev/null; then
 	    # Bisect failures in all steps after "-1" step.
 	    # Note, the negative above is to handle non-numeric scores like