Summary:
Records in the module summary index whether the bitcode was compiled
with the option necessary to enable splitting the LTO unit
(e.g. -fsanitize=cfi, -fwhole-program-vtables, or -fsplit-lto-unit).
The information is passed down to the ModuleSummaryIndex builder via a
new module flag "EnableSplitLTOUnit", which is propagated onto a flag
on the summary index.
This is then used during the LTO link to check whether all linked
summaries were built with the same value of this flag. If not, an error
is issued when we detect a situation requiring whole program visibility
of the class hierarchy. This is the case when both of the following
conditions are met:
1) We are performing LowerTypeTests or Whole Program Devirtualization.
2) There are type tests or type checked loads in the code.
Note I have also changed the ThinLTOBitcodeWriter to also gate the
module splitting on the value of this flag.
Reviewers: pcc
Subscribers: ormris, mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, dang, llvm-commits
Differential Revision: https://reviews.llvm.org/D53890
llvm-svn: 350948
Summary:
ThinLTO imports alias as a copy of a aliasee, so when we import such functions with type tests we will
need type ids used by function. However after D49565 we pick types only during processing of
FunctionSummary which is not happening for such aliesees.
Example:
Unit U1 with a type, a functions F with the type check, and an alias A to the function.
Unit U2 with only call to the alias A.
In particular, this happens when we use -mconstructor-aliases, which is default.
So if c++ unit only creates instance of the class, without calling any other methods it will lack of
necessary type ids, which will result in false CFI reports.
Reviewers: tejohnson, eugenis
Subscribers: pcc, mehdi_amini, inglorion, eraman, hiraditya, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D52201
llvm-svn: 342574
Summary:
Currently all type ids are emitted into the index file when it is
written. For distributed ThinLTO, that meant that all type ids were
being duplicated into every single distributed index file, regardless of
whether they were referenced, leading to huge amounts of unnecessary
duplication and size bloat.
Keep track of the type id GUIDs actually referenced by the GV summary
records being emitted, and only emit those type IDs.
Add a new test, and fix test/Assembler/thinlto-summary.ll so that all
type ids are referenced to prevent deletion in that test.
Reviewers: pcc
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, vitalybuka, llvm-commits
Differential Revision: https://reviews.llvm.org/D49565
llvm-svn: 337503
Teresa Johnson