all: use built-in min, max functions

Change-Id: Ie76ebb556d635068342747f3f91dd7dc423df531
GitHub-Last-Rev: aea61fb3a054e6bd24f4684f90fb353d5682cd0b
GitHub-Pull-Request: golang/go#73340
Reviewed-on: https://go-review.googlesource.com/c/go/+/664677
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>

4 files changed, 13 insertions, 20 deletions

diff --git a/src/internal/poll/copy_file_range_unix.go b/src/internal/poll/copy_file_range_unix.go
index d3d3aaeed1..d39c5a339d 100644
--- a/src/internal/poll/copy_file_range_unix.go
+++ b/src/internal/poll/copy_file_range_unix.go
@@ -16,10 +16,7 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
 	}
 
 	for remain > 0 {
-		max := remain
-		if max > maxCopyFileRangeRound {
-			max = maxCopyFileRangeRound
-		}
+		max := min(remain, maxCopyFileRangeRound)
 		n, e := copyFileRange(dst, src, int(max))
 		if n > 0 {
 			remain -= n
diff --git a/src/os/root_unix.go b/src/os/root_unix.go
index 19a84c4da0..74320451d5 100644
--- a/src/os/root_unix.go
+++ b/src/os/root_unix.go
@@ -272,9 +272,7 @@ func readlinkat(fd int, name string) (string, error) {
 		if e != nil {
 			return "", e
 		}
-		if n < 0 {
-			n = 0
-		}
+		n = max(n, 0)
 		if n < len {
 			return string(b[0:n]), nil
 		}
diff --git a/src/runtime/debug/garbage_test.go b/src/runtime/debug/garbage_test.go
index cd91782d27..506f698ad7 100644
--- a/src/runtime/debug/garbage_test.go
+++ b/src/runtime/debug/garbage_test.go
@@ -18,7 +18,7 @@ func TestReadGCStats(t *testing.T) {
 
 	var stats GCStats
 	var mstats runtime.MemStats
-	var min, max time.Duration
+	var minimum, maximum time.Duration
 
 	// First ReadGCStats will allocate, second should not,
 	// especially if we follow up with an explicit garbage collection.
@@ -52,11 +52,11 @@ func TestReadGCStats(t *testing.T) {
 			if dt != time.Duration(mstats.PauseNs[off]) {
 				t.Errorf("stats.Pause[%d] = %d, want %d", i, dt, mstats.PauseNs[off])
 			}
-			if max < dt {
-				max = dt
-			}
-			if min > dt || i == 0 {
-				min = dt
+			maximum = max(maximum, dt)
+			if i == 0 {
+				minimum = dt
+			} else {
+				minimum = min(minimum, dt)
 			}
 			off = (off + len(mstats.PauseNs) - 1) % len(mstats.PauseNs)
 		}
@@ -64,8 +64,8 @@ func TestReadGCStats(t *testing.T) {
 
 	q := stats.PauseQuantiles
 	nq := len(q)
-	if q[0] != min || q[nq-1] != max {
-		t.Errorf("stats.PauseQuantiles = [%d, ..., %d], want [%d, ..., %d]", q[0], q[nq-1], min, max)
+	if q[0] != minimum || q[nq-1] != maximum {
+		t.Errorf("stats.PauseQuantiles = [%d, ..., %d], want [%d, ..., %d]", q[0], q[nq-1], minimum, maximum)
 	}
 
 	for i := 0; i < nq-1; i++ {
diff --git a/src/time/sleep_test.go b/src/time/sleep_test.go
index 285a2e748c..b9e81b98fe 100644
--- a/src/time/sleep_test.go
+++ b/src/time/sleep_test.go
@@ -968,17 +968,15 @@ func BenchmarkParallelTimerLatency(b *testing.B) {
 	}
 	var total float64
 	var samples float64
-	max := Duration(0)
+	maximum := Duration(0)
 	for _, s := range stats {
-		if s.max > max {
-			max = s.max
-		}
+		maximum = max(maximum, s.max)
 		total += s.sum
 		samples += float64(s.count)
 	}
 	b.ReportMetric(0, "ns/op")
 	b.ReportMetric(total/samples, "avg-late-ns")
-	b.ReportMetric(float64(max.Nanoseconds()), "max-late-ns")
+	b.ReportMetric(float64(maximum.Nanoseconds()), "max-late-ns")
 }
 
 // Benchmark timer latency with staggered wakeup times and varying CPU bound