Native Coverage support in Soong (gcov)

This is configured the same as make -- a global NATIVE_COVERAGE=true
flag to allow native coverage, then COVERAGE_PATHS=path1,path2,... to
turn it on for certain paths.

There are .gcnodir files exported to Make and saved in $OUT/coverage/...
files which are `ar` archives containing all of the compiler-produced
.gcno files for a particular executable / shared library.

Unlike the Make implementation, this only passes links the helper
library (automatically through --coverage) when one of the object files
or static libraries being used actually has coverage enabled.

Host support is currently disabled, since we set -nodefaultlibs, which
prevents libclang_rt.profile-*.a from being picked up automatically.

Bug: 32749731
Test: NATIVE_COVERAGE=true COVERAGE_PATHS=system/core/libcutils m -j libbacktrace libutils tombstoned
      $OUT/coverage/system/lib*/libcutils.gcnodir looks correct (self)
      $OUT/coverage/system/lib*/libbacktrace.gcnodir looks correct (static)
      $OUT/coverage/system/lib*/libutils.gcnodir doesn't exist (shared)
      $OUT/coverage/system/bin/tombstoned.gcnodir looks correct (executable)
Test: NATIVE_COVERAGE=true COVERAGE_PATHS=external/libcxxabi m -j libc++
      Confirm that $OUT/coverage/system/lib*/libc++.gcnodir looks correct (whole_static_libs)
Change-Id: I48aaa0ba8d76e50e9c2d1151421c0c6dc8ed79a9

2 files changed, 18 insertions, 0 deletions

diff --git a/android/config.go b/android/config.go
index eaacef71..b4b0be87 100644
--- a/android/config.go
+++ b/android/config.go
@@ -471,3 +471,18 @@ func (c *deviceConfig) VndkVersion() string {
 func (c *deviceConfig) BtConfigIncludeDir() string {
 	return String(c.config.ProductVariables.BtConfigIncludeDir)
 }
+
+func (c *deviceConfig) NativeCoverageEnabled() bool {
+	return Bool(c.config.ProductVariables.NativeCoverage)
+}
+
+func (c *deviceConfig) CoverageEnabledForPath(path string) bool {
+	if c.config.ProductVariables.CoveragePaths != nil {
+		for _, prefix := range *c.config.ProductVariables.CoveragePaths {
+			if strings.HasPrefix(path, prefix) {
+				return true
+			}
+		}
+	}
+	return false
+}
diff --git a/android/variable.go b/android/variable.go
index 24c58dff..29f7c318 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -131,6 +131,9 @@ type productVariables struct {
 	ClangTidy  *bool   `json:",omitempty"`
 	TidyChecks *string `json:",omitempty"`
 
+	NativeCoverage *bool     `json:",omitempty"`
+	CoveragePaths  *[]string `json:",omitempty"`
+
 	DevicePrefer32BitExecutables *bool `json:",omitempty"`
 	HostPrefer32BitExecutables   *bool `json:",omitempty"`