From ccd992355df7192993c666236047820244914598 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Tue, 16 Apr 2024 21:19:13 +0200
Subject: Adding upstream version 1.21.8.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 src/runtime/fastlog2_test.go | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 src/runtime/fastlog2_test.go

(limited to 'src/runtime/fastlog2_test.go')

diff --git a/src/runtime/fastlog2_test.go b/src/runtime/fastlog2_test.go
new file mode 100644
index 0000000..ae0f40b
--- /dev/null
+++ b/src/runtime/fastlog2_test.go
@@ -0,0 +1,34 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"math"
+	"runtime"
+	"testing"
+)
+
+func TestFastLog2(t *testing.T) {
+	// Compute the euclidean distance between math.Log2 and the FastLog2
+	// implementation over the range of interest for heap sampling.
+	const randomBitCount = 26
+	var e float64
+
+	inc := 1
+	if testing.Short() {
+		// Check 1K total values, down from 64M.
+		inc = 1 << 16
+	}
+	for i := 1; i < 1<<randomBitCount; i += inc {
+		l, fl := math.Log2(float64(i)), runtime.Fastlog2(float64(i))
+		d := l - fl
+		e += d * d
+	}
+	e = math.Sqrt(e)
+
+	if e > 1.0 {
+		t.Fatalf("imprecision on fastlog2 implementation, want <=1.0, got %f", e)
+	}
+}
-- 
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