[go/release-branch.go1.26] [release-branch.go1.26] cmd/compile: fix slice backing store analysis
5 views
Skip to first unread message
Cuong Manh Le (Gerrit)
Sep 22, 2026, 10:45:51 PMSep 22
to goph...@pubsubhelper.golang.org, golang-co...@googlegroups.com
Cuong Manh Le has uploaded the change for review![]( "Open in Gerrit")
Commit message
[release-branch.go1.26] cmd/compile: fix slice backing store analysis
The range over slice statement keeps a pointer to the backing store of
the slice, making it from exclusive to nonexclusive at that point. Thus
we need to mark it as transition there.
Fixes #81689
Change-Id: I7292b5644ac658fa3a6ccd9fa949b454d2f3d770
Reviewed-on: https://go-review.googlesource.com/c/go/+/789060
Reviewed-by: Keith Randall <k...@golang.org>
Reviewed-by: Keith Randall <k...@google.com>
LUCI-TryBot-Result: golang...@luci-project-accounts.iam.gserviceaccount.com <golang...@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cher...@google.com>
Auto-Submit: Cuong Manh Le <cuong.m...@gmail.com>
Change diff
diff --git a/src/cmd/compile/internal/slice/slice.go b/src/cmd/compile/internal/slice/slice.go
index 17eba5b..8d8492a 100644
--- a/src/cmd/compile/internal/slice/slice.go
+++ b/src/cmd/compile/internal/slice/slice.go
@@ -356,10 +356,11 @@
}
}
case ir.ORANGE:
- // Range over slice is ok.
n := n.(*ir.RangeStmt)
if i := tracking(n.X); i != nil {
i.okUses++
+ // Range over slice keeps a pointer to the backing store, see #79909.
+ addTransition(i, n)
}
case ir.OAS:
n := n.(*ir.AssignStmt)
diff --git a/test/codegen/append.go b/test/codegen/append.go
index d232f0b..8d0d1f0 100644
--- a/test/codegen/append.go
+++ b/test/codegen/append.go
@@ -204,7 +204,9 @@
for i, x := range r {
println(i, x)
}
- // amd64:`.*moveSliceNoCapNoScan\b`
+ // "range r" keeps pointer to backing store of r, there
+ // should not be `moveSliceNoCapNoScan` here, see #79909.
+ // amd64:-`.*moveSliceNoCapNoScan\b`
return r
}
diff --git a/test/fixedbugs/issue79909.go b/test/fixedbugs/issue79909.go
new file mode 100644
index 0000000..ef34238
--- /dev/null
+++ b/test/fixedbugs/issue79909.go
@@ -0,0 +1,38 @@
+// run
+
+// Copyright 2026 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 "strconv"
+
+var sink []int64
+
+//go:noinline
+func f() int64 {
+ var s []int64
+ for i := int64(1); i <= 4; i++ {
+ s = append(s, i)
+ }
+ if cap(s) != 4 {
+ return -1
+ }
+ sum := int64(0)
+ for idx, v := range s {
+ sum = sum*10 + v
+ if idx == 0 {
+ s = s[3:3]
+ s = append(s, 9, 9)
+ }
+ }
+ sink = s
+ return sum
+}
+
+func main() {
+ if got := f(); got != 1234 {
+ panic("unexpected result: " + strconv.Itoa(int(got)))
+ }
+}
Change information
Files:
- M src/cmd/compile/internal/slice/slice.go
- M test/codegen/append.go
- A test/fixedbugs/issue79909.go
Change size: S
Delta: 3 files changed, 43 insertions(+), 2 deletions(-)
Related details
Attention set is empty
Submit Requirements:
Code-Review
No-Unresolved-Comments
Review-Enforcement
TryBots-Pass
| Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings. |
Cuong Manh Le (Gerrit)
Sep 22, 2026, 10:46:07 PMSep 22
to goph...@pubsubhelper.golang.org, Keith Randall, golang-co...@googlegroups.com
Attention needed from Keith Randall
Cuong Manh Le voted Commit-Queue+1![]( "Open in Gerrit")
Submit Requirements:
Code-Review
No-Unresolved-Comments
Review-Enforcement
TryBots-Pass
| Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings. |
David Chase (Gerrit)
Sep 29, 2026, 11:27:57 AMSep 29
to Cuong Manh Le, goph...@pubsubhelper.golang.org, golang...@luci-project-accounts.iam.gserviceaccount.com, Keith Randall, golang-co...@googlegroups.com
Attention needed from Cuong Manh Le and Keith Randall
David Chase voted Code-Review+2![]( "Open in Gerrit")
Attention is currently required from:
- Cuong Manh Le
- Keith Randall
Submit Requirements:
Code-Review
No-Unresolved-Comments
Review-Enforcement
TryBots-Pass
| Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings. |
Michael Pratt (Gerrit)
Sep 30, 2026, 11:27:27 AMSep 30
to Cuong Manh Le, goph...@pubsubhelper.golang.org, Michael Pratt, David Chase, golang...@luci-project-accounts.iam.gserviceaccount.com, Keith Randall, golang-co...@googlegroups.com
Attention needed from Cuong Manh Le and Keith Randall
Michael Pratt voted![]( "Open in Gerrit")
| Auto-Submit | +1 |
| Code-Review | +2 |
Related details
Attention is currently required from:
- Cuong Manh Le
- Keith Randall
Submit Requirements:
Code-Review
No-Unresolved-Comments
Review-Enforcement
TryBots-Pass
| Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings. |
Gopher Robot (Gerrit)
Sep 30, 2026, 11:35:05 AMSep 30
to Cuong Manh Le, goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, Michael Pratt, David Chase, golang...@luci-project-accounts.iam.gserviceaccount.com, Keith Randall, golang-co...@googlegroups.com
Gopher Robot submitted the change![]( "Open in Gerrit")
Change information
Commit message:
[release-branch.go1.26] cmd/compile: fix slice backing store analysis
The range over slice statement keeps a pointer to the backing store of
the slice, making it from exclusive to nonexclusive at that point. Thus
we need to mark it as transition there.
Fixes #81689
Change-Id: I7292b5644ac658fa3a6ccd9fa949b454d2f3d770
Reviewed-on: https://go-review.googlesource.com/c/go/+/789060
Reviewed-by: Keith Randall <k...@golang.org>
Reviewed-by: Keith Randall <k...@google.com>
LUCI-TryBot-Result: golang...@luci-project-accounts.iam.gserviceaccount.com <golang...@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cher...@google.com>
Auto-Submit: Cuong Manh Le <cuong.m...@gmail.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/837305
Reviewed-by: David Chase <drc...@google.com>
Reviewed-by: Michael Pratt <mpr...@google.com>
Auto-Submit: Michael Pratt <mpr...@google.com>
Files:
- M src/cmd/compile/internal/slice/slice.go
- M test/codegen/append.go
- A test/fixedbugs/issue79909.go
Change size: S
Delta: 3 files changed, 43 insertions(+), 2 deletions(-)
Branch: refs/heads/release-branch.go1.26
Submit Requirements:
Code-Review: +2 by David Chase, +2 by Michael Pratt
Review-Enforcement: Code-Review+2 by David Chase, Code-Review+2 by Michael Pratt
TryBots-Pass: LUCI-TryBot-Result+1 by golang...@luci-project-accounts.iam.gserviceaccount.com
| Inspect html for hidden footers to help with email filtering. To unsubscribe visit settings. |
Reply all
Reply to author
Forward
0 new messages