Change subdir traversal to primarily cache information about what is available in subdirectories.
 - Rest of makefiles will move to using the information after it has been computed, instead of during subdir traversal.

Also, add 'make info-functions' target, which prints information on all the functions available in compiler-rt.

Also, add 'make help-devel' for listing help on targets intended for compiler-rt developers or direct users.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@93715 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Makefile b/Makefile
index cb964ce..1f47dd4 100644
--- a/Makefile
+++ b/Makefile
@@ -37,7 +37,12 @@
 	@echo "  all:   build all configurations"
 	@echo
 
-help-hidden: help
+help-devel: help
+	@echo "Development targets:"
+	@echo "  info-functions: list available compiler-rt functions"
+	@echo
+
+help-hidden: help-devel
 	@echo "Debugging variables:"
 	@echo "  DEBUGMAKE=1: enable some Makefile logging [default=]"
 	@echo "           =2: enable more Makefile logging"
@@ -46,6 +51,14 @@
 	@echo "  make-print-FOO: print information on the variable 'FOO'"
 	@echo
 
+info-functions:
+	@echo "compiler-rt Available Functions"
+	@echo
+	@echo "All Functions: $(AvailableFunctions)"
+	@$(foreach fn,$(AvailableFunctions),\
+	  printf "  %-20s - available in (%s)\n" $(fn)\
+	    "$(foreach key,$(AvailableIn.$(fn)),$($(key).Dir))";)
+
 # Provide default clean target which is extended by other templates.
 .PHONY: clean
 clean::
@@ -230,3 +243,18 @@
   $(info MAKE: Done processing Makefile)
   $(info  )
 endif
+
+###
+# Function Information
+#
+# FIXME: Factor out.
+
+AvailableObjects := $(sort $(foreach key,$(SubDirKeys),\
+	$($(key).ObjNames)))
+AvailableFunctions := $(AvailableObjects:%.o=%)
+
+# Compute lists of where each function is available.
+$(foreach key,$(SubDirKeys),\
+  $(foreach fn,$(subst .o,,$($(key).ObjNames)),\
+    $(call Append,AvailableIn.$(fn),$(key))))
+