internal/fuzz: more debug logging

Change-Id: I2c36baf423dde419aaa940ce9308088f3bf431f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/476718
Auto-Submit: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>

src/internal/fuzz/fuzz.go

@@ -322,7 +322,6 @@ func CoordinateFuzzing(ctx context.Context, opts CoordinateFuzzingOpts) (err err
 					if c.canMinimize() && result.canMinimize && c.crashMinimizing == nil {
 						// Send back to workers to find a smaller value that preserves
 						// at least one new coverage bit.
-
 						c.queueForMinimization(result, keepCoverage)
 					} else {
 						// Update the coordinator's coverage mask and save the value.
@@ -822,8 +821,10 @@ func (c *coordinator) refillInputQueue() {
 func (c *coordinator) queueForMinimization(result fuzzResult, keepCoverage []byte) {
 	if shouldPrintDebugInfo() {
 		c.debugLogf(
-			"queueing input for minimization, id: %s, crasher: %t",
+			"queueing input for minimization, id: %s, parent: %s, keepCoverage: %t, crasher: %t",
 			result.entry.Path,
+			result.entry.Parent,
+			keepCoverage,
 			result.crasherMsg != "",
 		)
 	}

src/internal/fuzz/worker.go

@@ -216,6 +216,16 @@ func (w *worker) coordinate(ctx context.Context) error {
 					result.crasherMsg = err.Error()
 				}
 			}
+			if shouldPrintDebugInfo() {
+				w.coordinator.debugLogf(
+					"input minimized, id: %s, original id: %s, crasher: %t, originally crasher: %t, minimizing took: %s",
+					result.entry.Path,
+					input.entry.Path,
+					result.crasherMsg != "",
+					input.crasherMsg != "",
+					result.totalDuration,
+				)
+			}
 			w.coordinator.resultC <- result
 		}
 	}