cmd/compile: add missing OINLCAll case in mayModifyPkgVar

CL 395541 made staticopy safe, stop applying the optimization once
seeing an expression that may modify global variables.

However, if a call expression was inlined, the analyzer mis-recognizes
and think that the expression is safe. For example:

	var x = 0
	var a = f()
	var b = x

are re-written to:

	var x = 0
	var a = ~r0
	var b = 0

even though it's not safe because "f()" may modify "x".

Fixing this by recognizing OINLCALL and mark the initialization as
not safe for staticopy.

Fixes #66585

Change-Id: Id930c0b7e74274195f54a498cc4c5a91c4e6d84d
Reviewed-on: https://go-review.googlesource.com/c/go/+/575175
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/compile/internal/staticinit/sched.go

@@ -890,6 +890,9 @@ func mayModifyPkgVar(n ir.Node) bool {
 		case ir.OCALLFUNC, ir.OCALLINTER:
 			return !ir.IsFuncPCIntrinsic(n.(*ir.CallExpr))
 
+		case ir.OINLCALL:
+			return true
+
 		case ir.OAPPEND, ir.OCLEAR, ir.OCOPY:
 			return true // could mutate a global array
 

test/fixedbugs/issue66585.go

@@ -0,0 +1,25 @@
+// run
+
+// Copyright 2024 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
+
+var x = 0
+var a = foo()
+var b = x
+
+func foo() int {
+	x++
+	return x
+}
+
+func main() {
+	if a != 1 {
+		panic("unexpected a value")
+	}
+	if b != 1 {
+		panic("unexpected b value")
+	}
+}