build: Set ccache base to build top

This enables ccache sharing between different build tree paths.

Change-Id: I99636bdd2779a6ccf0649f027e35cf67df44b6ae

1 files changed, 54 insertions, 0 deletions

diff --git a/core/combo/select.mk b/core/combo/select.mk
index df12e7e..967a3b2 100644
--- a/core/combo/select.mk
+++ b/core/combo/select.mk
@@ -47,3 +47,57 @@ $(combo_var_prefix)STATIC_LIB_SUFFIX := .a
 
 # Now include the combo for this specific target.
 include $(BUILD_COMBOS)/$(combo_target)$(combo_os_arch).mk
+
+ifneq ($(USE_CCACHE),)
+  # The default check uses size and modification time, causing false misses
+  # since the mtime depends when the repo was checked out
+  export CCACHE_COMPILERCHECK := content
+
+  # See man page, optimizations to get more cache hits
+  # implies that __DATE__ and __TIME__ are not critical for functionality.
+  # Ignore include file modification time since it will depend on when
+  # the repo was checked out
+  export CCACHE_SLOPPINESS := time_macros,include_file_mtime,file_macro
+
+  # Turn all preprocessor absolute paths into relative paths.
+  # Fixes absolute paths in preprocessed source due to use of -g.
+  # We don't really use system headers much so the rootdir is
+  # fine; ensures these paths are relative for all Android trees
+  # on a workstation.
+  export CCACHE_BASEDIR := $(ANDROID_BUILD_TOP)
+
+  # Workaround for ccache with clang.
+  # See http://petereisentraut.blogspot.com/2011/09/ccache-and-clang-part-2.html
+  export CCACHE_CPP2 := true
+
+  CCACHE_HOST_TAG := $(HOST_PREBUILT_TAG)
+  # If we are cross-compiling Windows binaries on Linux
+  # then use the linux ccache binary instead.
+  ifeq ($(HOST_OS)-$(BUILD_OS),windows-linux)
+    CCACHE_HOST_TAG := linux-$(HOST_PREBUILT_ARCH)
+  endif
+  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 := $(ccache)
+    endif
+    ccache =
+  endif
+endif
+
+# The C/C++ compiler can be wrapped by setting the CC/CXX_WRAPPER vars.
+ifdef CC_WRAPPER
+  ifneq ($(CC_WRAPPER),$(firstword $($(combo_var_prefix)CC)))
+    $(combo_var_prefix)CC := $(CC_WRAPPER) $($(combo_var_prefix)CC)
+  endif
+endif
+ifdef CXX_WRAPPER
+  ifneq ($(CXX_WRAPPER),$(firstword $($(combo_var_prefix)CXX)))
+    $(combo_var_prefix)CXX := $(CXX_WRAPPER) $($(combo_var_prefix)CXX)
+  endif
+endif