1 files changed, 40 insertions, 8 deletions
diff --git a/pkg/manager/diff.go b/pkg/manager/diff.go
index 64d0af444..aa640515d 100644
--- a/pkg/manager/diff.go
+++ b/pkg/manager/diff.go
@@ -297,9 +297,9 @@ func (dc *diffContext) monitorPatchedCoverage(ctx context.Context) error {
 		return nil
 	}
 	focusAreaStats := dc.new.progsPerArea()
-	if focusAreaStats[modifiedArea]+focusAreaStats[includesArea] > 0 {
-		log.Logf(0, "fuzzer has reached the modified code (%d + %d), continuing fuzzing",
-			focusAreaStats[modifiedArea], focusAreaStats[includesArea])
+	if focusAreaStats[symbolsArea]+focusAreaStats[filesArea]+focusAreaStats[includesArea] > 0 {
+		log.Logf(0, "fuzzer has reached the modified code (%d + %d + %d), continuing fuzzing",
+			focusAreaStats[symbolsArea], focusAreaStats[filesArea], focusAreaStats[includesArea])
 		return nil
 	}
 	log.Logf(0, "fuzzer has not reached the modified code in %s, aborting",
@@ -721,18 +721,32 @@ func (rr *reproRunner) Run(ctx context.Context, r *repro.Result) {
 }
 
 const (
-	modifiedArea = "modified"
+	symbolsArea  = "symbols"
+	filesArea    = "files"
 	includesArea = "included"
 )
 
-func PatchFocusAreas(cfg *mgrconfig.Config, gitPatches [][]byte) {
+func PatchFocusAreas(cfg *mgrconfig.Config, gitPatches [][]byte, baseHashes, patchedHashes map[string]string) {
+	funcs := modifiedSymbols(baseHashes, patchedHashes)
+	if len(funcs) > 0 {
+		log.Logf(0, "adding modified_functions to focus areas: %q", funcs)
+		cfg.Experimental.FocusAreas = append(cfg.Experimental.FocusAreas,
+			mgrconfig.FocusArea{
+				Name: symbolsArea,
+				Filter: mgrconfig.CovFilterCfg{
+					Functions: funcs,
+				},
+				Weight: 6.0,
+			})
+	}
+
 	direct, transitive := affectedFiles(cfg, gitPatches)
 	if len(direct) > 0 {
 		sort.Strings(direct)
-		log.Logf(0, "adding directly modified files to focus_order: %q", direct)
+		log.Logf(0, "adding directly modified files to focus areas: %q", direct)
 		cfg.Experimental.FocusAreas = append(cfg.Experimental.FocusAreas,
 			mgrconfig.FocusArea{
-				Name: modifiedArea,
+				Name: filesArea,
 				Filter: mgrconfig.CovFilterCfg{
 					Files: direct,
 				},
@@ -742,7 +756,7 @@ func PatchFocusAreas(cfg *mgrconfig.Config, gitPatches [][]byte) {
 
 	if len(transitive) > 0 {
 		sort.Strings(transitive)
-		log.Logf(0, "adding transitively affected to focus_order: %q", transitive)
+		log.Logf(0, "adding transitively affected to focus areas: %q", transitive)
 		cfg.Experimental.FocusAreas = append(cfg.Experimental.FocusAreas,
 			mgrconfig.FocusArea{
 				Name: includesArea,
@@ -808,3 +822,21 @@ func affectedFiles(cfg *mgrconfig.Config, gitPatches [][]byte) (direct, transiti
 	}
 	return
 }
+
+// If there are too many different symbols, they are no longer specific enough.
+// Don't use them to focus the fuzzer.
+const modifiedSymbolThreshold = 0.05
+
+func modifiedSymbols(baseHashes, patchedHashes map[string]string) []string {
+	var ret []string
+	for name, hash := range patchedHashes {
+		if baseHash, ok := baseHashes[name]; !ok || baseHash != hash {
+			ret = append(ret, name)
+			if float64(len(ret)) > float64(len(patchedHashes))*modifiedSymbolThreshold {
+				return nil
+			}
+		}
+	}
+	sort.Strings(ret)
+	return ret
+}