cmd/compile/internal/gc: treat cap/len as safe in mayAffectMemory

OLEN and OCAP can't affect memory state as long as their arguments don't. Re-organized case bodies to avoid duplicating same branches for recursive invocations. Change-Id: I30407143429f7dd1891badb70df88969ed267535 Reviewed-on: https://go-review.googlesource.com/133555 Run-TryBot: Iskander Sharipov <[email protected]> TryBot-Result: Gobot Gobot <[email protected]> Reviewed-by: Cherry Zhang <[email protected]>
cloudflare · Sep 17, 2018 · 2d82465 · 2d82465
1 parent 930ce09
commit 2d82465
Showing 1 changed file with 8 additions and 10 deletions.
diff --git a/src/cmd/compile/internal/gc/esc.go b/src/cmd/compile/internal/gc/esc.go
@@ -689,18 +689,16 @@ func (e *EscState) mayAffectMemory(n *Node) bool {
  switch n.Op {
  case ONAME, OCLOSUREVAR, OLITERAL:
  return false
- case ODOT, ODOTPTR:
- return e.mayAffectMemory(n.Left)
- case OIND, OCONVNOP:
- return e.mayAffectMemory(n.Left)
- case OCONV:
- return e.mayAffectMemory(n.Left)
- case OINDEX:
- return e.mayAffectMemory(n.Left) || e.mayAffectMemory(n.Right)
- case OADD, OSUB, OOR, OXOR, OMUL, OLSH, ORSH, OAND, OANDNOT, ODIV, OMOD:
+
+ // Left+Right group.
+ case OINDEX, OADD, OSUB, OOR, OXOR, OMUL, OLSH, ORSH, OAND, OANDNOT, ODIV, OMOD:
  return e.mayAffectMemory(n.Left) || e.mayAffectMemory(n.Right)
- case ONOT, OCOM, OPLUS, OMINUS, OALIGNOF, OOFFSETOF, OSIZEOF:
+
+ // Left group.
+ case ODOT, ODOTPTR, OIND, OCONVNOP, OCONV, OLEN, OCAP,
+ ONOT, OCOM, OPLUS, OMINUS, OALIGNOF, OOFFSETOF, OSIZEOF:
  return e.mayAffectMemory(n.Left)
+
  default:
  return true
  }