qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-18 00:04:43 -07:00
Code Releases Activity

cmd/compile: fix noopt builder, weird append case

Browse Source 
Turn off append-to-itself optimization if optimizations are turned off.

This optimization triggered a bug when doing
  s = append(s, s)
where we write to the leftmost s before reading the rightmost s.

Update #17039

Change-Id: I21996532d20a75db6ec8d49db50cb157a1360b80
Reviewed-on: https://go-review.googlesource.com/81816
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Keith Randall 2017-12-04 13:30:13 -08:00 committed by Keith Randall
parent 509ffb94ca
commit 9d70b3ae04
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/compile/internal/gc/ssa.go
View File

@ -737,7 +737,7 @@ func (s *state) stmt(n *Node) {
// Check whether we're writing the result of an append back to the same slice.
// If so, we handle it specially to avoid write barriers on the fast
// (non-growth) path.
if !samesafeexpr(n.Left, rhs.List.First()) {
if !samesafeexpr(n.Left, rhs.List.First()) || Debug['N'] != 0 {
break
}
// If the slice can be SSA'd, it'll be on the stack,