Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

cmd/compile: clarify Node.NonNil and Node.Bounded

Browse source 
Node.NonNil and Node.Bounded were a bit muddled. This led to #38496.
This change clarifies and documents them.

It also corrects one misuse.
However, since ssa conversion doesn't make full use of the bounded hint,
this correction doesn't change any generated code.
The next change will fix that.

Passes toolstash-check.

Change-Id: I2bcd487a0a4aef5d7f6090e653974fce0dce3b8e
Reviewed-on: https://go-review.googlesource.com/c/go/+/228787
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Josh Bleecher Snyder 2020-04-16 21:25:15 -07:00
parent 1f0738c157
commit 5abf5f831e
3 changed files with 32 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

28
src/cmd/compile/internal/gc/syntax.go
View file

@ -188,15 +188,39 @@ func (n *Node) SetImplicit(b bool) { n.flags.set(nodeImplicit, b) }
func (n *Node) SetIsDDD(b bool) { n.flags.set(nodeIsDDD, b) }
func (n *Node) SetDiag(b bool) { n.flags.set(nodeDiag, b) }
func (n *Node) SetColas(b bool) { n.flags.set(nodeColas, b) }
func (n *Node) SetNonNil(b bool) { n.flags.set(nodeNonNil, b) }
func (n *Node) SetTransient(b bool) { n.flags.set(nodeTransient, b) }
func (n *Node) SetBounded(b bool) { n.flags.set(nodeBounded, b) }
func (n *Node) SetHasCall(b bool) { n.flags.set(nodeHasCall, b) }
func (n *Node) SetLikely(b bool) { n.flags.set(nodeLikely, b) }
func (n *Node) SetHasVal(b bool) { n.flags.set(nodeHasVal, b) }
func (n *Node) SetHasOpt(b bool) { n.flags.set(nodeHasOpt, b) }
func (n *Node) SetEmbedded(b bool) { n.flags.set(nodeEmbedded, b) }
// MarkNonNil marks a pointer n as being guaranteed non-nil,
// on all code paths, at all times.
// During conversion to SSA, non-nil pointers won't have nil checks
// inserted before dereferencing. See state.exprPtr.
func (n *Node) MarkNonNil() {
if !n.Type.IsPtr() && !n.Type.IsUnsafePtr() {
Fatalf("MarkNonNil(%v), type %v", n, n.Type)
}
n.flags.set(nodeNonNil, true)
}
// SetBounded indicates whether operation n does not need safety checks.
// When n is an index or slice operation, n does not need bounds checks.
// When n is a dereferencing operation, n does not need nil checks.
func (n *Node) SetBounded(b bool) {
switch n.Op {
case OINDEX, OSLICE, OSLICEARR, OSLICE3, OSLICE3ARR, OSLICESTR:
// No bounds checks needed.
case ODOTPTR, ODEREF:
// No nil check needed.
default:
Fatalf("SetBounded(%v)", n)
}
n.flags.set(nodeBounded, b)
}
// MarkReadonly indicates that n is an ONAME with readonly contents.
func (n *Node) MarkReadonly() {
if n.Op != ONAME {