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| author | Keith Randall <khr@golang.org> | 2021-09-13 09:17:22 -0700 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2021-09-13 18:38:15 +0000 |
| commit | ac40c9872f6e8ef095dcc6ee556236782eee4f76 (patch) | |
| tree | fc3e6168541f973c796be3deb83a4ba9eceee31b | |
| parent | c8a58f29dcb2b4f38ca4fcf4d2a2a80f606c9573 (diff) | |
| download | go-ac40c9872f6e8ef095dcc6ee556236782eee4f76.tar.gz go-ac40c9872f6e8ef095dcc6ee556236782eee4f76.zip | |
reflect: fix _faststr optimization
CL 345486 introduced an optimization to reflect's map accesses
which is not quite correct. We can't use the optimized code if the
value type is >128 bytes.
See cmd/compile/internal/walk/walk.go:mapfast
Fixes #48357
Change-Id: I8e3c7858693083dd4393a8de48ca5fa47bab66f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/349593
Trust: Keith Randall <khr@golang.org>
Trust: Joe Tsai <joetsai@digital-static.net>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Trust: Martin Möhrmann <martin@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
Run-TryBot: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Martin Möhrmann <martin@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
| -rw-r--r-- | src/reflect/value.go | 4 | ||||
| -rw-r--r-- | test/fixedbugs/issue48357.go | 20 |
2 files changed, 22 insertions, 2 deletions
diff --git a/src/reflect/value.go b/src/reflect/value.go index 6e9aaabe8a..bc48a76ce6 100644 --- a/src/reflect/value.go +++ b/src/reflect/value.go @@ -1517,7 +1517,7 @@ func (v Value) MapIndex(key Value) Value { // of unexported fields. var e unsafe.Pointer - if key.kind() == String && tt.key.Kind() == String { + if key.kind() == String && tt.key.Kind() == String && tt.elem.size <= maxValSize { k := *(*string)(key.ptr) e = mapaccess_faststr(v.typ, v.pointer(), k) } else { @@ -2128,7 +2128,7 @@ func (v Value) SetMapIndex(key, elem Value) { key.mustBeExported() tt := (*mapType)(unsafe.Pointer(v.typ)) - if key.kind() == String && tt.key.Kind() == String { + if key.kind() == String && tt.key.Kind() == String && tt.elem.size <= maxValSize { k := *(*string)(key.ptr) if elem.typ == nil { mapdelete_faststr(v.typ, v.pointer(), k) diff --git a/test/fixedbugs/issue48357.go b/test/fixedbugs/issue48357.go new file mode 100644 index 0000000000..5b39fc43d4 --- /dev/null +++ b/test/fixedbugs/issue48357.go @@ -0,0 +1,20 @@ +// run + +// Copyright 2021 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 main + +import "reflect" + +type T [129]byte + +func main() { + m := map[string]T{} + v := reflect.ValueOf(m) + v.SetMapIndex(reflect.ValueOf("a"), reflect.ValueOf(T{})) + g = m["a"] +} + +var g T |