From: Michael Pratt <mpratt@google.com>
Date: Wed, 21 Aug 2024 20:17:16 +0000 (-0400)
Subject: internal/runtime/maps: avoid passing unused key return
X-Git-Tag: go1.24rc1~563
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=775837f51f03245bcba333094b4b3742f8fbfca3;p=gostls13.git

internal/runtime/maps: avoid passing unused key return

For #54766.

Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest-swissmap
Change-Id: Idee1e021e3cef8f0c031e8f06efbcf6e88918d8a
Reviewed-on: https://go-review.googlesource.com/c/go/+/622376
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---

diff --git a/src/internal/runtime/maps/map.go b/src/internal/runtime/maps/map.go
index ad6edd65bf..a4fa07635a 100644
--- a/src/internal/runtime/maps/map.go
+++ b/src/internal/runtime/maps/map.go
@@ -360,8 +360,7 @@ func (m *Map) Used() uint64 {
 // Get performs a lookup of the key that key points to. It returns a pointer to
 // the element, or false if the key doesn't exist.
 func (m *Map) Get(key unsafe.Pointer) (unsafe.Pointer, bool) {
-	_, elem, ok := m.getWithKey(key)
-	return elem, ok
+	return m.getWithoutKey(key)
 }
 
 func (m *Map) getWithKey(key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer, bool) {
@@ -375,6 +374,18 @@ func (m *Map) getWithKey(key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer, bo
 	return m.directoryAt(idx).getWithKey(hash, key)
 }
 
+func (m *Map) getWithoutKey(key unsafe.Pointer) (unsafe.Pointer, bool) {
+	hash := m.typ.Hasher(key, m.seed)
+
+	if m.dirLen == 0 {
+		_, elem, ok := m.getWithKeySmall(hash, key)
+		return elem, ok
+	}
+
+	idx := m.directoryIndex(hash)
+	return m.directoryAt(idx).getWithoutKey(hash, key)
+}
+
 func (m *Map) getWithKeySmall(hash uintptr, key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer, bool) {
 	g := groupReference{
 		typ:  m.typ,
diff --git a/src/internal/runtime/maps/table.go b/src/internal/runtime/maps/table.go
index 86e5dce10d..ac200133c9 100644
--- a/src/internal/runtime/maps/table.go
+++ b/src/internal/runtime/maps/table.go
@@ -231,6 +231,32 @@ func (t *table) getWithKey(hash uintptr, key unsafe.Pointer) (unsafe.Pointer, un
 	}
 }
 
+func (t *table) getWithoutKey(hash uintptr, key unsafe.Pointer) (unsafe.Pointer, bool) {
+	seq := makeProbeSeq(h1(hash), t.groups.lengthMask)
+	for ; ; seq = seq.next() {
+		g := t.groups.group(seq.offset)
+
+		match := g.ctrls().matchH2(h2(hash))
+
+		for match != 0 {
+			i := match.first()
+
+			slotKey := g.key(i)
+			if t.typ.Key.Equal(key, slotKey) {
+				return g.elem(i), true
+			}
+			match = match.removeFirst()
+		}
+
+		match = g.ctrls().matchEmpty()
+		if match != 0 {
+			// Finding an empty slot means we've reached the end of
+			// the probe sequence.
+			return nil, false
+		}
+	}
+}
+
 // PutSlot returns a pointer to the element slot where an inserted element
 // should be written, and ok if it returned a valid slot.
 //