From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Sun, 2 Dec 2018 18:15:35 +0000 (-0800)
Subject: runtime: speed up ifaceeq for direct ifaces
X-Git-Tag: go1.13beta1~1329
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=694cd005c3943027a4533a0a534837108ccd66f6;p=gostls13.git

runtime: speed up ifaceeq for direct ifaces

name                    old time/op  new time/op  delta
EfaceCmpDiff-8           421ns ± 3%   299ns ± 3%  -28.93%  (p=0.000 n=92+94)
EfaceCmpDiffIndirect-8   497ns ± 4%   496ns ± 3%     ~     (p=0.840 n=98+92)

Change-Id: Id1a8c779413ba35ab0f58d055870b6a0714b51b7
Reviewed-on: https://go-review.googlesource.com/c/152163
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
---

diff --git a/src/runtime/alg.go b/src/runtime/alg.go
index 887dbebdeb..1c6795a1fa 100644
--- a/src/runtime/alg.go
+++ b/src/runtime/alg.go
@@ -224,7 +224,10 @@ func efaceeq(t *_type, x, y unsafe.Pointer) bool {
 		panic(errorString("comparing uncomparable type " + t.string()))
 	}
 	if isDirectIface(t) {
-		return eq(noescape(unsafe.Pointer(&x)), noescape(unsafe.Pointer(&y)))
+		// Direct interface types are ptr, chan, map, func, and single-element structs/arrays thereof.
+		// Maps and funcs are not comparable, so they can't reach here.
+		// Ptrs, chans, and single-element items can be compared directly using ==.
+		return x == y
 	}
 	return eq(x, y)
 }
@@ -238,7 +241,8 @@ func ifaceeq(tab *itab, x, y unsafe.Pointer) bool {
 		panic(errorString("comparing uncomparable type " + t.string()))
 	}
 	if isDirectIface(t) {
-		return eq(noescape(unsafe.Pointer(&x)), noescape(unsafe.Pointer(&y)))
+		// See comment in efaceeq.
+		return x == y
 	}
 	return eq(x, y)
 }
diff --git a/src/runtime/runtime_test.go b/src/runtime/runtime_test.go
index 8263d4059a..5ea9cbd88a 100644
--- a/src/runtime/runtime_test.go
+++ b/src/runtime/runtime_test.go
@@ -70,6 +70,18 @@ func BenchmarkEfaceCmpDiff(b *testing.B) {
 	}
 }
 
+func BenchmarkEfaceCmpDiffIndirect(b *testing.B) {
+	efaceCmp1 = [2]int{1, 2}
+	efaceCmp2 = [2]int{1, 2}
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < 100; j++ {
+			if efaceCmp1 != efaceCmp2 {
+				b.Fatal("bad comparison")
+			}
+		}
+	}
+}
+
 func BenchmarkDefer(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		defer1()