How to use pre-compiled tools like externel toolchain

I want to use pre-compiled tools that can reduce compile time , but i don't konw how to do it.

I analyse the source code, I found that there is a subdir.mk to create a stampfile.

tools/Makefile

tools_enabled = $(foreach tool,$(sort $(tools-y) $(tools-)),$(if $(filter $(tool),$(tools-y)),y,n))
$(eval $(call stampfile,$(curdir),tools,compile,,_$(subst $(space),,$(tools_enabled)),$(STAGING_DIR_HOST)))
$(eval $(call stampfile,$(curdir),tools,check,$(TMP_DIR)/.build,,$(STAGING_DIR_HOST)))

subdir.mk

ifndef DUMP_TARGET_DB
# 1: subdir
# 2: target
# 3: build type
# 4: build variant
# 5: all variants
# Parameters: <subdir> <name> <target> <depends> <config options> <stampfile location>
define stampfile
  $(1)/stamp-$(3):=$(if $(6),$(6),$(STAGING_DIR))/stamp/.$(2)_$(3)$(5)
  $$($(1)/stamp-$(3)): $(TMP_DIR)/.build $(4)
	@+$(SCRIPT_DIR)/timestamp.pl -n $$($(1)/stamp-$(3)) $(1) $(4) || \
		$(MAKE) $(if $(QUIET),--no-print-directory) $$($(1)/flags-$(3)) $(1)/$(3)
	@mkdir -p $$$$(dirname $$($(1)/stamp-$(3)))
	@touch $$($(1)/stamp-$(3))

  $$(if $(call debug,$(1),v),,.SILENT: $$($(1)/stamp-$(3)))

  .PRECIOUS: $$($(1)/stamp-$(3)) # work around a make bug

  $(1)//clean:=$(1)/stamp-$(3)/clean
  $(1)/stamp-$(3)/clean: FORCE
	@rm -f $$($(1)/stamp-$(3))

endef
endif

Do precompiled tools work if fixing the timestamp? and how to fix timestamp?
Thanks for your reply.