Revert "Fix and cleanup."
This reverts commit f28bad5227dd566395e458b5266e716d7fa5f958.
Change-Id: Ib64936457a1236fabbe7c6b9c56f52ef650342e7
diff --git a/core/main.mk b/core/main.mk
index e04c4c7..3bf9cae 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -234,7 +234,23 @@
# These are the modifier targets that don't do anything themselves, but
# change the behavior of the build.
# (must be defined before including definitions.make)
-INTERNAL_MODIFIER_TARGETS := showcommands all
+INTERNAL_MODIFIER_TARGETS := showcommands all incrementaljavac
+
+.PHONY: incrementaljavac
+incrementaljavac: ;
+
+# WARNING:
+# ENABLE_INCREMENTALJAVAC should NOT be enabled by default, because change of
+# a Java source file won't trigger rebuild of its dependent Java files.
+# You can only enable it by adding "incrementaljavac" to your make command line.
+# You are responsible for the correctness of the incremental build.
+# This may decrease incremental build time dramatically for large Java libraries,
+# such as core.jar, framework.jar, etc.
+ENABLE_INCREMENTALJAVAC :=
+ifneq (,$(filter incrementaljavac, $(MAKECMDGOALS)))
+ENABLE_INCREMENTALJAVAC := true
+MAKECMDGOALS := $(filter-out incrementaljavac, $(MAKECMDGOALS))
+endif
# EMMA_INSTRUMENT_STATIC merges the static emma library to each emma-enabled module.
ifeq (true,$(EMMA_INSTRUMENT_STATIC))