--- a/make/Defs-internal.gmk	Wed Jul 05 17:36:33 2017 +0200
+++ b/make/Defs-internal.gmk	Mon Feb 28 10:56:10 2011 +0100
@@ -28,21 +28,63 @@
 # not contain rules.
 #
 
-# Indicate that we are visiting a separate repo or component 
+# The build times report is turned off by setting REPORT_BUILD_TIMES to nothing.
+# This is necessary for the target clobber/clean which will erase the
+# directories where the buildtimes are stored.
+REPORT_BUILD_TIMES=1
+# Store the build times in this directory.
+BUILDTIMESDIR=$(ABS_OUTPUTDIR)/tmp/buildtimes
+
+# Record starting time for build of a sub repository.
+define RecordStartTime
+$(MKDIR) -p $(BUILDTIMESDIR)
+$(DATE) '+%Y %m %d %H %M %S' | $(NAWK) '{ print $$1,$$2,$$3,$$4,$$5,$$6,($$4*3600+$$5*60+$$6) }' > $(BUILDTIMESDIR)/build_time_start_$1
+$(DATE) '+%Y-%m-%d %H:%M:%S' > $(BUILDTIMESDIR)/build_time_start_$1_human_readable
+endef
+
+# Indicate that we started to build a sub repository and record starting time. 
 define MakeStart
-$(PRINTF) "\n\n%s\n%s\n##### %-60.60s #####\n%s\n" \
+$(call RecordStartTime,$1)
+$(PRINTF) "\n\n%s\n%s\n##### %-60.60s #####\n%s\n\n" \
 "########################################################################" \
 "########################################################################" \
-"Entering $1 for target $2" \
+"Entering $1 for target(s) $2" \
 "########################################################################"
 endef
 
-define MakeFinish
-$(PRINTF) "%s\n##### %-60.60s #####\n%s\n%s\n\n" \
+# Record ending time and calculate the difference and store it in a
+# easy to read format. Handles builds that cross midnight. Expects
+# that a build will never take 24 hours or more. 
+define RecordEndTime
+$(DATE) '+%Y %m %d %H %M %S' | $(NAWK) '{ print $$1,$$2,$$3,$$4,$$5,$$6,($$4*3600+$$5*60+$$6) }' > $(BUILDTIMESDIR)/build_time_end_$1
+$(DATE) '+%Y-%m-%d %H:%M:%S' > $(BUILDTIMESDIR)/build_time_end_$1_human_readable
+$(ECHO) `$(CAT) $(BUILDTIMESDIR)/build_time_start_$1` `$(CAT) $(BUILDTIMESDIR)/build_time_end_$1` $1 | \
+  $(NAWK) '{ F=$$7; T=$$14; if (F > T) { T+=3600*24 }; D=T-F; H=int(D/3600); \
+             M=int((D-H*3600)/60); S=D-H*3600-M*60; printf("%02d:%02d:%02d %s\n",H,M,S,$$15); }' \
+  > $(BUILDTIMESDIR)/build_time_diff_$1
+endef
+
+# Indicate that we are done.
+# Record ending time and print out the total time it took to build.
+define MakeFinish 
+$(if $(REPORT_BUILD_TIMES),$(call RecordEndTime,$1),) 
+$(PRINTF) "%s\n##### %-60.60s #####\n%s\n##### %-60.60s #####\n%s\n\n" \
 "########################################################################" \
-"Leaving $1 for target $2" \
+"Leaving $1 for target(s) $2" \
 "########################################################################" \
-"########################################################################"
+$(if $(REPORT_BUILD_TIMES),"Build time `$(CAT) $(BUILDTIMESDIR)/build_time_diff_$1` for target(s) $2","") \
+"########################################################################" 
+endef
+
+# Find all build_time_* files and print their contents in a list sorted
+# on the name of the sub repository.
+define ReportBuildTimes
+$(PRINTF) "-- Build times ----------\nTarget %s\nStart %s\nEnd   %s\n%s\n%s\n-------------------------\n" \
+$1 \
+"`$(CAT) $(BUILDTIMESDIR)/build_time_start_TOTAL_human_readable`" \
+"`$(CAT) $(BUILDTIMESDIR)/build_time_end_TOTAL_human_readable`" \
+"`$(LS) $(BUILDTIMESDIR)/build_time_diff_* | $(GREP) -v _TOTAL | $(XARGS) $(CAT) | $(SORT) -k 2`" \
+"`$(CAT) $(BUILDTIMESDIR)/build_time_diff_TOTAL`"
 endef
 
 ifdef OPENJDK