Commit Graph

3 Commits

Author SHA1 Message Date
Peter Collingbourne cfbd089237 Reland r313157, "ThinLTO: Correctly follow aliasee references when dead stripping." which was reverted in r313222.
This reland includes a fix for the LowerTypeTests pass so that it
looks past aliases when determining which type identifiers are live.

Differential Revision: https://reviews.llvm.org/D37842

llvm-svn: 313229
2017-09-14 05:02:59 +00:00
Hans Wennborg ae050afeb9 Revert r313157 "ThinLTO: Correctly follow aliasee references when dead stripping."
This broke Chromium's CFI build; see crbug.com/765004.

> We were previously handling aliases during dead stripping by adding
> the aliased global's "original name" GUID to the worklist. This will
> lead to incorrect behaviour if the global has local linkage because
> the original name GUID will not correspond to the global's GUID in
> the summary.
>
> Because an alias is just another name for the global that it
> references, there is no need to mark the referenced global as used,
> or to follow references from any other copies of the global. So all
> we need to do is to follow references from the aliasee's summary
> instead of the alias.
>
> Differential Revision: https://reviews.llvm.org/D37789

llvm-svn: 313222
2017-09-14 00:40:14 +00:00
Peter Collingbourne d067c8ed59 ThinLTO: Correctly follow aliasee references when dead stripping.
We were previously handling aliases during dead stripping by adding
the aliased global's "original name" GUID to the worklist. This will
lead to incorrect behaviour if the global has local linkage because
the original name GUID will not correspond to the global's GUID in
the summary.

Because an alias is just another name for the global that it
references, there is no need to mark the referenced global as used,
or to follow references from any other copies of the global. So all
we need to do is to follow references from the aliasee's summary
instead of the alias.

Differential Revision: https://reviews.llvm.org/D37789

llvm-svn: 313157
2017-09-13 17:09:20 +00:00