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cmd/compile: fix escape reason for MAKESLICE with no cap

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When explaining why the slice from a make() call escapes for the -m -m
message, we print "non-const size" if any one of Isconst(n.Left) and
Isconst(n.Right) return false; but for OMAKESLICE nodes with no cap,
n.Right is nil, so Isconst(n.Right, CTINT) will be always false.

Only call Isconst on n.Right if it's not nil.

Fixes #41635

Change-Id: I8729801a9b234b68ae40adad64d66fa7653adf09
Reviewed-on: https://go-review.googlesource.com/c/go/+/257641
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Alberto Donizetti <alb.donizetti@gmail.com>
This commit is contained in:
Alberto Donizetti 2020-09-26 09:42:59 +02:00
parent 5755bad42a
commit e572218d12
2 changed files with 19 additions and 1 deletions
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2
src/cmd/compile/internal/gc/escape.go
View File

@ -1053,7 +1053,7 @@ func (e *Escape) newLoc(n *Node, transient bool) *EscLocation {
if mustHeapAlloc(n) { if mustHeapAlloc(n) {
why := "too large for stack" why := "too large for stack"
if n.Op == OMAKESLICE && (!Isconst(n.Left, CTINT) || !Isconst(n.Right, CTINT)) { if n.Op == OMAKESLICE && (!Isconst(n.Left, CTINT) || (n.Right != nil && !Isconst(n.Right, CTINT))) {
why = "non-constant size" why = "non-constant size"
} }
e.flow(e.heapHole().addr(n, why), loc) e.flow(e.heapHole().addr(n, why), loc)

18
test/fixedbugs/issue41635.go Normal file
View File

@ -0,0 +1,18 @@
//errorcheck -0 -m -m
// Copyright 2020 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
func f() { // ERROR ""
b1 := make([]byte, 1<<17) // ERROR "too large for stack" ""
b2 := make([]byte, 100, 1<<17) // ERROR "too large for stack" ""
n, m := 100, 200
b1 = make([]byte, n) // ERROR "non-constant size" ""
b2 = make([]byte, 100, m) // ERROR "non-constant size" ""
_, _ = b1, b2
}