[release-branch.go1.21] cmd/compile: fix escape analysis of string min/max

When I was plumbing min/max support through the compiler, I was
thinking mostly about numeric argument types. As a result, I forgot
that escape analysis would need to be aware that min/max can operate
on string values, which contain pointers.

Updates #64565.
Fixes #64567.

Change-Id: I36127ce5a2da942401910fa0f9de922726c9f94d
Reviewed-on: https://go-review.googlesource.com/c/go/+/547715
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
(cherry picked from commit 34416d7f6f93cd6562636e311c362ebe421f1a4c)
Reviewed-on: https://go-review.googlesource.com/c/go/+/547757
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/compile/internal/escape/call.go b/src/cmd/compile/internal/escape/call.go
index c69eca1998778ad88a60b80ce11e870e04861434..36e606bf2090cb2eafe0a991325a724c0ee0f27b 100644 (file)
--- a/src/cmd/compile/internal/escape/call.go
+++ b/src/cmd/compile/internal/escape/call.go
@@ -186,7 +186,7 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
                argument(e.discardHole(), &call.X)
                argument(e.discardHole(), &call.Y)
 
-       case ir.ODELETE, ir.OMAX, ir.OMIN, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+       case ir.ODELETE, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
                call := call.(*ir.CallExpr)
                fixRecoverCall(call)
                for i := range call.Args {
@@ -194,6 +194,14 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
                }
                argumentRType(&call.RType)
 
+       case ir.OMIN, ir.OMAX:
+               call := call.(*ir.CallExpr)
+               fixRecoverCall(call)
+               for i := range call.Args {
+                       argument(ks[0], &call.Args[i])
+               }
+               argumentRType(&call.RType)
+
        case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE, ir.OCLEAR:
                call := call.(*ir.UnaryExpr)
                argument(e.discardHole(), &call.X)

diff --git a/test/escape_calls.go b/test/escape_calls.go
index aa7c7f516cf96ef38dc7ab1b8617e7cbf5b246e7..5424c006ee4d0d8b2f9bc032f2e7d80a55c8cbdf 100644 (file)
--- a/test/escape_calls.go
+++ b/test/escape_calls.go
@@ -52,3 +52,10 @@ func bar() {
        s := "string"
        f([]string{s}) // ERROR "\[\]string{...} escapes to heap"
 }
+
+func strmin(a, b, c string) string { // ERROR "leaking param: a to result ~r0 level=0" "leaking param: b to result ~r0 level=0" "leaking param: c to result ~r0 level=0"
+       return min(a, b, c)
+}
+func strmax(a, b, c string) string { // ERROR "leaking param: a to result ~r0 level=0" "leaking param: b to result ~r0 level=0" "leaking param: c to result ~r0 level=0"
+       return max(a, b, c)
+}

diff --git a/test/fixedbugs/issue64565.go b/test/fixedbugs/issue64565.go
new file mode 100644 (file)
index 0000000..634025c
--- /dev/null
+++ b/test/fixedbugs/issue64565.go
@@ -0,0 +1,15 @@
+// run
+
+// Copyright 2023 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() {
+       m := "0"
+       for _, c := range "321" {
+               m = max(string(c), m)
+               println(m)
+       }
+}

diff --git a/test/fixedbugs/issue64565.out b/test/fixedbugs/issue64565.out
new file mode 100644 (file)
index 0000000..1f242fa
--- /dev/null
+++ b/test/fixedbugs/issue64565.out
@@ -0,0 +1,3 @@
+3
+3
+3