PHI that has at least one unrelocated input cannot cause any issues by itself,
though its uses should be carefully verified. With this patch PHIs are allowed
to have any inputs but when all inputs are unrelocated the PHI is marked as
unrelocated and if not all inputs are unrelocated then the PHI is marked as
poisoned. Poisoned pointers can be used only in three ways: to derive new
pointers, in PHIs or in comparisons against constants that are exclusively
derived from null.
Patch by Daniil Suchkov!
Differential Revision: https://reviews.llvm.org/D41006
llvm-svn: 321438
Summary:
This patch allows to use derived pointers (GEPs/bitcasts) of unrelocated
base pointers. We care only about the uses of these derived pointers.
It is acheived by two changes:
1. When we have enough information to say if the pointer is unrelocated at some
point or not, we walk all BBs to remove from their Contributions all valid defs
of unrelocated pointers (GEP with unrelocated base or bitcast of unrelocated
pointer).
2. When it comes to verification we just ignore instructions that were removed
at stage 1.
Patch by Daniil Suchkov!
Reviewers: anna, reames, apilipenko, mkazantsev
Reviewed By: anna, mkazantsev
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D40289
llvm-svn: 319838
Today the safepoint IR verifier catches some unrelocated uses of base
pointers that are actually valid.
With this change, we narrow down the set of false positives.
Specifically, the verifier knows about compares to null and compares
between 2 unrelocated pointers.
Reviewed by: skatkov
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D35057
llvm-svn: 307392
Original Patch and summary by Philip Reames.
RewriteStatepointsForGC tries to rewrite a function in a manner where
the optimizer can't end up using a pointer value after it might have
been relocated by a safepoint. This pass checks the invariant that
RSForGC is supposed to establish and that (if we constructed semantics
correctly) later passes must preserve.
This has been a really useful diagnostic tool when initially developing
the rewriting scheme and has found numerous bugs.
Differential Revision: https://reviews.llvm.org/D15940
Reviewed by: swaroop.sridhar, mjacob
Subscribers: llvm-commits
llvm-svn: 307112
Max Kazantsev