diff --git a/core/ccache.mk b/core/ccache.mk index d67bce6c7b..893c98564f 100644 --- a/core/ccache.mk +++ b/core/ccache.mk @@ -14,6 +14,21 @@ # limitations under the License. # +# We no longer provide a ccache prebuilt. +# +# Ours was old, and had a number of issues that triggered non-reproducible +# results and other failures. Newer ccache versions may fix some of those +# issues, but at the large scale of our build servers, we weren't seeing +# significant performance gains from using ccache -- you end up needing very +# good locality and/or very large caches if you're building many different +# configurations. +# +# Local no-change full rebuilds were showing better results, but why not just +# use incremental builds at that point? +# +# So if you still want to use ccache, continue setting USE_CCACHE, but also set +# the CCACHE_EXEC environment variable to the path to your ccache executable. +ifneq ($(CCACHE_EXEC),) ifneq ($(filter-out false,$(USE_CCACHE)),) # The default check uses size and modification time, causing false misses # since the mtime depends when the repo was checked out @@ -36,17 +51,11 @@ ifneq ($(filter-out false,$(USE_CCACHE)),) # See http://petereisentraut.blogspot.com/2011/09/ccache-and-clang-part-2.html export CCACHE_CPP2 := true - CCACHE_HOST_TAG := $(HOST_PREBUILT_TAG) - ccache := prebuilts/misc/$(CCACHE_HOST_TAG)/ccache/ccache - # Check that the executable is here. - ccache := $(strip $(wildcard $(ccache))) - ifdef ccache - ifndef CC_WRAPPER - CC_WRAPPER := $(ccache) - endif - ifndef CXX_WRAPPER - CXX_WRAPPER := $(ccache) - endif - ccache = + ifndef CC_WRAPPER + CC_WRAPPER := $(CCACHE_EXEC) + endif + ifndef CXX_WRAPPER + CXX_WRAPPER := $(CCACHE_EXEC) endif endif +endif