mirror of
https://github.com/golang/go
synced 2024-07-21 01:55:06 +00:00
585c9e8412
Allow shifts by signed amounts. Panic if the shift amount is negative. TODO: We end up doing two compares per shift, see Ian's comment https://github.com/golang/go/issues/19113#issuecomment-443241799 that we could do it with a single comparison in the normal case. The prove pass mostly handles this code well. For instance, it removes the <0 check for cases like this: if s >= 0 { _ = x << s } _ = x << len(a) This case isn't handled well yet: _ = x << (y & 0xf) I'll do followon CLs for unhandled cases as needed. Update #19113 R=go1.13 Change-Id: I839a5933d94b54ab04deb9dd5149f32c51c90fa1 Reviewed-on: https://go-review.googlesource.com/c/158719 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
15 lines
312 B
Go
15 lines
312 B
Go
// compile
|
|
|
|
// Copyright 2009 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
|
|
|
|
func main() {
|
|
var s int = 0
|
|
var x int = 0
|
|
x = x << s // as of 1.13, these are ok
|
|
x = x >> s // as of 1.13, these are ok
|
|
}
|