This enabled opaque pointers by default in LLVM. The effect of this
is twofold:
* If IR that contains *neither* explicit ptr nor %T* types is passed
to tools, we will now use opaque pointer mode, unless
-opaque-pointers=0 has been explicitly passed.
* Users of LLVM as a library will now default to opaque pointers.
It is possible to opt-out by calling setOpaquePointers(false) on
LLVMContext.
A cmake option to toggle this default will not be provided. Frontends
or other tools that want to (temporarily) keep using typed pointers
should disable opaque pointers via LLVMContext.
Differential Revision: https://reviews.llvm.org/D126689
Currently, if there is a module that contains a strong definition of
a global variable and a module that has both a weak definition for
the same global and a reference to it, it may result in an undefined symbol error
while linking with ThinLTO.
It happens because:
* the strong definition become internal because it is read-only and can be imported;
* the weak definition gets replaced by a declaration because it's non-prevailing;
* the strong definition failed to be imported because the destination module
already contains another definition of the global yet this def is non-prevailing.
The patch adds a check to computeImportForReferencedGlobals() that allows
considering a global variable for being imported even if the module contains
a definition of it in the case this def has an interposable linkage type.
Note that currently the check is based only on the linkage type
(and this seems to be enough at the moment), but it might be worth to account
the information whether the def is prevailing or not.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D95943