[PATCH] D47103: Implement strip.invariant.group
Piotr Padlewski via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Wed May 23 16:17:16 PDT 2018
Prazek added inline comments.
================
Comment at: clang/lib/CodeGen/CGExpr.cpp:3858
+ }
+ }
+
----------------
rjmccall wrote:
> Please add a comment explaining why this is necessary. (I'm actually not sure why it is, because surely the invariant groups we generate don't contain assumptions about memory from fields, right?)
Short answer: you can only make virtual calls on a dynamic pointer that carries invariant.group and you can't do anything other because it could leak the information about this pointer (which when used with comparison could break devirtualization).
Repository:
rL LLVM
https://reviews.llvm.org/D47103
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