tree 8f5e353f6f67a86b8e357a5ebe0fd5ba9a9bafdd
parent 85822390223b59c6fa37f59af9781ec0b0e09297
author Cherry Zhang <cherryyz@google.com> 1545445731 -0500
committer Cherry Zhang <cherryyz@google.com> 1546015680 +0000

passes: mark alloca live when its address is used

When a stack slot's address is taken, it could potentially be
live any point after it. It could also be initialized
"indirectly", like

  tmp = phi(&a, &b)
  *tmp = ...

In this case we didn't see the initialization of either a or b.
But the slot needs to be live. This CL fixes this.

The slot could also be initialized some time later (after a few
statepoints), or never. We don't know for sure. So we need to
pre-zero it, if we don't otherwise know it is initialized.

Also some minor cleanup:
- no need to add pointerless allocas into AddrTakenAllocas.
- delete an unused function (only relevant for relocations).

Change-Id: I44fdb4fb08883bffd51e125aabd6421cbec820e8
Reviewed-on: https://go-review.googlesource.com/c/155761
Reviewed-by: Than McIntosh <thanm@google.com>