Initial prototype of object layout generation.

Makefile

Index: Makefile
diff --git a/Makefile b/Makefile
index 288c257396de19895d85a6d399c520e939d5cb02..c7123694163b17e40fbfe7f41b28af08d0fc23b2 100644
--- a/Makefile
+++ b/Makefile
@@ -193,6 +193,7 @@ endif
 # ----------------- available targets: --------------------
 # - "dependencies": pulls in external dependencies (currently: GYP)
 # - "grokdump": rebuilds heap constants lists used by grokdump
+# - "objects": rebuilds heap object descriptions
 # - any arch listed in ARCHES (see below)
 # - any mode listed in MODES
 # - every combination <arch>.<mode>, e.g. "ia32.release"
@@ -402,6 +403,11 @@ $(ENVFILE).new:
 	@mkdir -p $(OUTDIR); echo "GYPFLAGS=$(GYPFLAGS)" > $(ENVFILE).new; \
 	    echo "CXX=$(CXX)" >> $(ENVFILE).new
 
+# Heap object descriptions.
+objects: src/objects-gen.cc src/objects-gen.h
+src/objects-gen.%: tools/objects-gen.%.mustache src/objects.layout
+	@tools/objects-generator.py $< src/objects.layout > $@
+
 # Heap constants for grokdump.
 DUMP_FILE = tools/v8heapconst.py
 grokdump: ia32.release