Add a coverage suffix to avoid Ninja file regeneration.
This CL uses the environment variable, EMMA_INSTRUMENT to determine whether or not coverage is enabled. If coverage is enabled, it adds a bunch of suffixes to the files generated in out/soong/ folders.
This change reduces the build time by avoiding ninja regeneration when users simply switches from atest to atest --experimental-coverage, or vice versa, and no Android.bp changes are made.
Bug: 331444846
Test: Locally run m libc, and then EMMA_INSTRUMENT m libc twice, no ninja regenerations required. Compared the hash of out/target/product/vsoc_x86_64/ between the before-change repo and after-change repo. Only diff is the after-change directory contains an extra file `out/target/product/vsoc_x86_64/.installable_files` while the original directory has only `out/target/product/vsoc_x86_64/.installable_files.previous`, both files have the same hash.
Change-Id: I91eb1134ac552f47a40f3d5ddaab630d146b0773
diff --git a/core/config.mk b/core/config.mk
index ae65944..b011101 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -1252,8 +1252,15 @@
# consistency with those defined in BoardConfig.mk files.
include $(BUILD_SYSTEM)/android_soong_config_vars.mk
-SOONG_VARIABLES := $(SOONG_OUT_DIR)/soong.$(TARGET_PRODUCT).variables
-SOONG_EXTRA_VARIABLES := $(SOONG_OUT_DIR)/soong.$(TARGET_PRODUCT).extra.variables
+# EMMA_INSTRUMENT is set to true when coverage is enabled. Creates a suffix to
+# differeciate the coverage version of ninja files. This will save 5 minutes of
+# build time used to regenerate ninja.
+ifeq (true,$(EMMA_INSTRUMENT))
+COVERAGE_SUFFIX := .coverage
+endif
+
+SOONG_VARIABLES := $(SOONG_OUT_DIR)/soong.$(TARGET_PRODUCT)$(COVERAGE_SUFFIX).variables
+SOONG_EXTRA_VARIABLES := $(SOONG_OUT_DIR)/soong.$(TARGET_PRODUCT)$(COVERAGE_SUFFIX).extra.variables
ifeq ($(CALLED_FROM_SETUP),true)
include $(BUILD_SYSTEM)/ninja_config.mk