[release-branch.go1.20] cmd/compile: fix wrong escape analysis for go/defer generic calls

For go/defer calls like "defer f(x, y)", the compiler rewrites it to:

	x1, y1 := x, y
	defer func() { f(x1, y1) }()

However, if "f" needs runtime type information, the "RType" field will
refer to the outer ".dict" param, causing wrong liveness analysis.

To fix this, if "f" refers to outer ".dict", the dict param will be
copied to an autotmp, and "f" will refer to this autotmp instead.

Fixes #58467

Change-Id: I238b6e75441442b5540d39bc818205398e80c94d
Reviewed-on: https://go-review.googlesource.com/c/go/+/466035
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/go/+/467935
Reviewed-by: Michael Pratt <mpratt@google.com>

src/cmd/compile/internal/escape/call.go

@@ -19,7 +19,7 @@ func (e *escape) call(ks []hole, call ir.Node) {
 	var init ir.Nodes
 	e.callCommon(ks, call, &init, nil)
 	if len(init) != 0 {
-		call.(*ir.CallExpr).PtrInit().Append(init...)
+		call.(ir.InitNode).PtrInit().Append(init...)
 	}
 }
 
@@ -38,6 +38,18 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
 		argumentFunc(nil, k, argp)
 	}
 
+	argumentRType := func(rtypep *ir.Node) {
+		rtype := *rtypep
+		if rtype == nil {
+			return
+		}
+		// common case: static rtype/itab argument, which can be evaluated within the wrapper instead.
+		if addr, ok := rtype.(*ir.AddrExpr); ok && addr.Op() == ir.OADDR && addr.X.Op() == ir.OLINKSYMOFFSET {
+			return
+		}
+		e.wrapExpr(rtype.Pos(), rtypep, init, call, wrapper)
+	}
+
 	switch call.Op() {
 	default:
 		ir.Dump("esc", call)
@@ -153,6 +165,7 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
 				argument(e.heapHole(), &args[i])
 			}
 		}
+		argumentRType(&call.RType)
 
 	case ir.OCOPY:
 		call := call.(*ir.BinaryExpr)
@@ -163,6 +176,7 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
 			copiedK = e.heapHole().deref(call, "copied slice")
 		}
 		argument(copiedK, &call.Y)
+		argumentRType(&call.RType)
 
 	case ir.OPANIC:
 		call := call.(*ir.UnaryExpr)
@@ -179,6 +193,7 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
 		for i := range call.Args {
 			argument(e.discardHole(), &call.Args[i])
 		}
+		argumentRType(&call.RType)
 
 	case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE:
 		call := call.(*ir.UnaryExpr)
@@ -192,6 +207,7 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
 		call := call.(*ir.BinaryExpr)
 		argument(ks[0], &call.X)
 		argument(e.discardHole(), &call.Y)
+		argumentRType(&call.RType)
 	}
 }
 

test/fixedbugs/issue58341.go

@@ -0,0 +1,30 @@
+// compile
+
+// 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 p
+
+type S[T comparable] struct {
+	m map[T]T
+}
+
+func (s S[T]) M1(node T) {
+	defer delete(s.m, node)
+}
+
+func (s S[T]) M2(node T) {
+	defer func() {
+		delete(s.m, node)
+	}()
+}
+
+func (s S[T]) M3(node T) {
+	defer f(s.m, node)
+}
+
+//go:noinline
+func f[T comparable](map[T]T, T) {}
+
+var _ = S[int]{}