Clarify what this RemapFlag actually means.
- Change the flag name to match its intended behaviour.
- Clearly document that it's not supposed to affect globals.
- Add a host of FIXMEs to indicate how to fix the behaviour to match
the intent of the flag.
RF_IgnoreMissingLocals should only affect the behaviour of
RemapInstruction for function-local operands; namely, for operands of
type Argument, Instruction, and BasicBlock. Currently, it is *only*
passed into RemapInstruction calls (and the transitive MapValue calls
that it makes).
When I split Metadata from Value I didn't understand the flag, and I
used it in a bunch of places for "global" metadata.
This commit doesn't have any functionality change, but prepares to
cleanup MapMetadata and MapValue.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265628 91177308-0d34-0410-b5e6-96231b3b80d8
Instead of copying arguments from the source function to the
destination, steal them. This has a few advantages.
- The ValueMap doesn't need to be seeded with (or cleared of)
Arguments.
- Often the destination function won't have created any arguments yet,
so this avoids malloc traffic.
- Argument names don't need to be copied.
Because argument lists are lazy, this required a new
Function::stealArgumentListFrom helper.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265519 91177308-0d34-0410-b5e6-96231b3b80d8
Split the loop through compile units in mapUnneededSubprograms in two.
First, visit imported entities to ensure that we've visited all need
subprograms. Second, visit subprograms, and drop the ones we don't
need.
Hypothetically this protects against a subprogram from one compile unit
being referenced from an imported entity in a different compile unit. I
don't think that's valid IR (a debug info expert could confirm), but I
think the refactor makes the code more clear.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265233 91177308-0d34-0410-b5e6-96231b3b80d8
IRLinker::mapUnneededSubprograms has to be sure that any "needed"
subprograms get linked in. Rather than traversing through imported
entities using llvm::getSubprogram, call MapMetadata. The latter
memoizes the result in the ValueMap (sharing work with
IRLinker::linkNamedMDNodes proper), and makes the local SmallPtrSet
redundant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265231 91177308-0d34-0410-b5e6-96231b3b80d8
Instead of checking live during MapMetadata whether a subprogram is
needed, seed the ValueMap with `nullptr` up-front.
There is a small hypothetical functionality change. Previously, calling
MapMetadataOp on a node whose "scope:" chain led to an unneeded
subprogram would return nullptr. However, if that were ever called,
then the subprogram would be needed; a situation that the IRMover is
supposed to avoid a priori!
Besides cleaning up the code a little, this restores a nice property:
MapMetadataOp returns the same as MapMetadata.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265229 91177308-0d34-0410-b5e6-96231b3b80d8
Support seeding a ValueMap with nullptr for Metadata entries, a
situation I didn't consider in the Metadata/Value split.
I added a ValueMapper::getMappedMD accessor that returns an
Optional<Metadata*> with the mapped (possibly null) metadata. IRMover
needs to use this to avoid modifying the map when it's checking for
unneeded subprograms. I updated a call from bugpoint since I find the
new code clearer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265228 91177308-0d34-0410-b5e6-96231b3b80d8
Since we have moved to a model where functions are imported in bulk from
each source module after making summary-based importing decisions, there
is no longer a need to link metadata as a postpass, and all users have
been removed.
This essentially reverts r255909 and follow-on fixes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264763 91177308-0d34-0410-b5e6-96231b3b80d8
After comdat processing, the symbols still go through regular symbol
resolution.
We were not doing it for linkonce symbols since they are lazy linked.
This fixes pr27044.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264288 91177308-0d34-0410-b5e6-96231b3b80d8
If not for lazy linking of linkonce GVs, comdats are just a
preprocessing before symbol resolution.
Lazy linking complicates it since when we pick a visible member of
comdat, we have to make sure the rest of it passes symbol resolution
too.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264223 91177308-0d34-0410-b5e6-96231b3b80d8
If a comdat is dropped, all symbols in it are dropped.
If a comdat is kept, the symbols survive to pass regular symbol
resolution.
With this patch we do that for all global symbols.
The added test is a copy of test/tools/gold/X86/comdat.ll that we now
pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264192 91177308-0d34-0410-b5e6-96231b3b80d8
A really unfortunate design of llvm-link and related libraries is that
they operate one module at a time.
This means they can copy a GV to the destination module that should not
be there in the final result because a later bitcode file takes
precedence.
We already handled cases like a strong GV replacing a weak for example.
One case that is not currently handled is a comdat replacing another.
This doesn't happen in ELF, but with COFF largest selection kind it is
possible.
In "llvm-link a.ll b.ll" if the selected comdat was from a.ll,
everything will work and we will not copy the comdat from b.ll.
But if we run "llvm-link b.ll a.ll", we fail to delete the already
copied comdat from b.ll. This patch fixes that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@264103 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
ThinLTO is relying on linkInModule to import selected function.
However a lot of "magic" was hidden in linkInModule and the IRMover,
who would rename and promote global variables on the fly.
This is moving to an approach where the steps are decoupled and the
client is reponsible to specify the list of globals to import.
As a consequence some test are changed because they were relying on
the previous behavior which was importing the definition of *every*
single global without control on the client side.
Now the burden is on the client to decide if a global has to be imported
or not.
Reviewers: tejohnson
Subscribers: joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D18122
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@263863 91177308-0d34-0410-b5e6-96231b3b80d8
(Resubmitting after fixing missing file issue)
With the changes in r263275, there are now more than just functions in
the summary. Completed the renaming of data structures (started in
r263275) to reflect the wider scope. In particular, changed the
FunctionIndex* data structures to ModuleIndex*, and renamed related
variables and comments. Also renamed the files to reflect the changes.
A companion clang patch will immediately succeed this patch to reflect
this renaming.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@263513 91177308-0d34-0410-b5e6-96231b3b80d8
With the changes in r263275, there are now more than just functions in
the summary. Completed the renaming of data structures (started in
r263275) to reflect the wider scope. In particular, changed the
FunctionIndex* data structures to ModuleIndex*, and renamed related
variables and comments. Also renamed the files to reflect the changes.
A companion clang patch will immediately succeed this patch to reflect
this renaming.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@263490 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Unless we plan to do later postpass metadata linking (ThinLTO special mode),
always invoke metadata materialization at the start of IRLinker::run().
This avoids the need for clients who use lazy metadata loading to
explicitly invoke materializeMetadata before the IRMover, which in
turn invokes IRLinker::run and needs materialized metadata for mapping.
Came up in the context of an LLD issue (D17982).
Reviewers: rafael
Subscribers: silvas, llvm-commits
Differential Revision: http://reviews.llvm.org/D17992
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@263143 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
As discussed on IRC, move the ThinLTOGlobalProcessing code out of
the linker, and into TransformUtils. The name of the class is changed
to FunctionImportGlobalProcessing.
Reviewers: joker.eph, rafael
Subscribers: joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D17081
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@260395 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Available externally definitions are considered declarations for the
linker and eventually dropped. As such they are not allowed to be
in comdats. Remove any such imported functions from comdats.
Reviewers: rafael
Subscribers: davidxl, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D16120
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@260122 91177308-0d34-0410-b5e6-96231b3b80d8
The stripNullSubprograms function is very inefficient because
it walks all subprograms in all compile units in the dest module
any time a new module is linked in. For LTO in particular this will
get increasingly expensive as more modules are linked.
This patch improves the efficiency in several ways. The first is that
no scanning is necessary when there were no unneeded subprograms
identified in the first place. The second is that only the newly-linked
module's compile unit metadata should be examined.
Fixes PR26346.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259049 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch is provided in preparation for removing autoconf on 1/26. The proposal to remove autoconf on 1/26 was discussed on the llvm-dev thread here: http://lists.llvm.org/pipermail/llvm-dev/2016-January/093875.html
"I felt a great disturbance in the [build system], as if millions of [makefiles] suddenly cried out in terror and were suddenly silenced. I fear something [amazing] has happened."
- Obi Wan Kenobi
Reviewers: chandlerc, grosbach, bob.wilson, tstellarAMD, echristo, whitequark
Subscribers: chfast, simoncook, emaste, jholewinski, tberghammer, jfb, danalbert, srhines, arsenm, dschuff, jyknight, dsanders, joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D16471
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258861 91177308-0d34-0410-b5e6-96231b3b80d8
For metadata postpass linking, after importing all functions, we need
to recursively walk through any nodes reached via imported functions to
locate needed subprogram metadata. Some might only be reached indirectly
via the variable list for an inlined function.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258728 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Since we are currently not doing incremental importing there is
no need to link metadata as a postpass. The module linker will
only link in the imported subroutines due to the functionality
added by r256003.
(Note that the metadata postpass linking functionalitiy is still
used by llvm-link, and may be needed here in the future if a more
incremental strategy is adopted.)
Reviewers: joker.eph
Subscribers: joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D16424
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258458 91177308-0d34-0410-b5e6-96231b3b80d8
Replace sequences of count() followed by operator[] with either
find() or insert(), depending on the context.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258405 91177308-0d34-0410-b5e6-96231b3b80d8
Fix the condition for when the new global takes over the name of
the existing one to be the negation of the condition for the new
global to get internal linkage.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258355 91177308-0d34-0410-b5e6-96231b3b80d8
Function::copyAttributesFrom will copy the personality function, prefix
data and prolog data from the source function to the new function, and
is invoked when the IRMover copies the function prototype. This puts a
reference to a constant in the source module on a function in the dest
module, which causes an error when deleting the source module after
importing, since the personality function in the source module still has
uses (this would presumably also be an issue for the prologue and prefix
data). Remove the copies added to the dest copy when creating the new
prototype, as they are mapped properly when/if we link the function body.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257420 91177308-0d34-0410-b5e6-96231b3b80d8
Due to the new in-place ThinLTO symbol handling support added in
r257174, we now invoke renameModuleForThinLTO on the current
module from within the FunctionImport pass.
Additionally, renameModuleForThinLTO no longer needs to return the
Module as it is performing the renaming in place on the one provided.
This commit will be immediately preceeded by a companion clang patch to
remove its invocation of renameModuleForThinLTO.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257181 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Move ThinLTO global value processing functions out of ModuleLinker and
into a new ThinLTOGlobalProcessor class, which performs any necessary
linkage and naming changes on the given module in place.
As a result, renameModuleForThinLTO no longer needs to create a new
Module when performing any necessary local to global promotion on a
module that we are possibly exporting from during a ThinLTO backend
compilation.
During function importing the ThinLTO processing is still invoked from
the ModuleLinker (via the new class), as it needs to perform renaming and
linkage changes on the source module, e.g. in order to get the correct
renaming during local to global promotion.
Reviewers: joker.eph
Subscribers: davidxl, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D15696
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257174 91177308-0d34-0410-b5e6-96231b3b80d8
Follow-up to r257000: DIImportedEntity can reach a DISubprogram via
its entity, but also via its scope. Handle the latter case as well.
PR26037.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257019 91177308-0d34-0410-b5e6-96231b3b80d8
It is illegal to have a null entity in a DIImportedEntity, so
we must link in a DISubprogram metadata node referenced by one,
even if the associated function is not linked in or inlined anywhere.
Fixes PR26037.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257000 91177308-0d34-0410-b5e6-96231b3b80d8
As suggested in review for r255909, rename MDMaterialized to AllowTemps,
and identify the name of the boolean flag being set in calls to
saveMetadataList.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256653 91177308-0d34-0410-b5e6-96231b3b80d8
As suggested in review for r255909, add a way to ensure that temporary
MD used as keys in the MetadataToID map during ThinLTO importing are not
RAUWed.
Add support for marking an MDNode as not replaceable. Clear the new
CanReplace flag when adding a temporary MD node to the MetadataToID map
and clear it when destroying the map.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256648 91177308-0d34-0410-b5e6-96231b3b80d8
Remove a couple ModuleLinker methods and a related static function that
are no longer used after the linker split.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256162 91177308-0d34-0410-b5e6-96231b3b80d8
It was only used on lib/Linker and the use was "dead" since it was used on a
function the IRMover had just moved.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256019 91177308-0d34-0410-b5e6-96231b3b80d8
Renamed variables to be more reflective of whether they are
an instance of Linker, IRLinker or ModuleLinker. Also fix a stale
comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256011 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Third patch split out from http://reviews.llvm.org/D14752.
Only map in needed DISubroutine metadata (imported or otherwise linked
in functions and other DISubroutine referenced by inlined instructions).
This is supported for ThinLTO, LTO and llvm-link --only-needed, with
associated tests for each one.
Depends on D14838.
Reviewers: dexonsmith, joker.eph
Subscribers: davidxl, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D14843
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256003 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Second patch split out from http://reviews.llvm.org/D14752.
Maps metadata as a post-pass from each module when importing complete,
suturing up final metadata to the temporary metadata left on the
imported instructions.
This entails saving the mapping from bitcode value id to temporary
metadata in the importing pass, and from bitcode value id to final
metadata during the metadata linking postpass.
Depends on D14825.
Reviewers: dexonsmith, joker.eph
Subscribers: davidxl, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D14838
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255909 91177308-0d34-0410-b5e6-96231b3b80d8
Passing in a std::unique_ptr should help find errors when the module
is used after being linked into another module.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255842 91177308-0d34-0410-b5e6-96231b3b80d8
This patch converts code that has access to a LLVMContext to not take a
diagnostic handler.
This has a few advantages
* It is easier to use a consistent diagnostic handler in a single program.
* Less clutter since we are not passing a handler around.
It does make it a bit awkward to implement some C APIs that return a
diagnostic string. I will propose new versions of these APIs and
deprecate the current ones.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255571 91177308-0d34-0410-b5e6-96231b3b80d8
A linker normally has two stages: symbol resolution and "moving stuff".
In lib/Linker there is the complication of lazy linking some globals,
but it was still far more mixed than it needed to.
This splits the linker into a lower level IRMover and the linker proper.
The IRMover just takes a list of globals to move and a callback that
lets the user control what is lazy linked.
The main motivation is that now tools/gold (and soon lld) can use their
own symbol resolution to instruct IRMover what to do.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255254 91177308-0d34-0410-b5e6-96231b3b80d8
We were deciding to not link an available_externally gv over a
declaration, but then copying over the body anyway.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255169 91177308-0d34-0410-b5e6-96231b3b80d8
Now instead of changing it to the new format and then linking, it just
handles the old format while copying it over.
The main differences are:
* There is no rauw in the source module.
* An old format input is always upgraded.
The first item helps with having a sane API that passes in a GV list to
the linker.
The second one is a small step in deprecating the old format.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254907 91177308-0d34-0410-b5e6-96231b3b80d8
Creates a module and performs necessary renaming/promotion of locals
that may be exported to another module.
Split out of D15024.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254802 91177308-0d34-0410-b5e6-96231b3b80d8
Before this patch the diagnostic handler was optional. If it was not
passed, the one in the LLVMContext was used.
That is probably not a pattern we want to follow. If each area has an
optional callback, there is a sea of callbacks and it is hard to follow
which one is called.
Doing this also found cases where the callback is a nice addition, like
testing that no errors or warnings are reported.
The other option is to always use the diagnostic handler in the
LLVMContext. That has a few problems
* To implement the C API we would have to set the diag handler and then
set it back to the original value.
* Code that creates the context might be far away from code that wants
the diagnostics.
I do have a patch that implements the second option and will send that as
an RFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254777 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Fix import from module with appending var, which cannot be imported. The
first fix is to remove an overly-aggressive error check.
The second fix is to deal with restructuring introduced to the module
linker yesterday in r254418 (actually, this fix was included already
in r254559, just added some additional cleanup).
Test by Mehdi Amini.
Reviewers: joker.eph, rafael
Subscribers: joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D15156
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254624 91177308-0d34-0410-b5e6-96231b3b80d8
There is no real reason the index has to have the concept of an
exporting Module. We should be able to have one single unique
instance of the Index, and it should be read-only after creation
for the whole ThinLTO processing.
The linker plugin should be able to process multiple modules (in
parallel or in sequence) with the same index.
The only reason the ExportingModule was present seems to be to
implement hasExportedFunctions() that is used by the Module linker
to decide what to do with the current Module.
For now I replaced it with a query to the map of Modules path to
see if this module was declared in the Index and consider that if
it is the case then it is probably exporting function.
On the long term the Linker interface needs to evolve and this
call should not be needed anymore.
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254581 91177308-0d34-0410-b5e6-96231b3b80d8
This replaces DoNotLinkFromSource with ValuesToLink. It also moves the
computation of ValuesToLink earlier.
It is a bit simpler and an important step in slitting the linker into an
ir mover and a linker proper.
The test change is because we now avoid creating dead declarations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254559 91177308-0d34-0410-b5e6-96231b3b80d8
Having to import an alias as declaration is not thinlto specific.
The test difference are because when we already have a decl and we are
not importing it, we just leave the decl alone.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254556 91177308-0d34-0410-b5e6-96231b3b80d8
This was an omission when handling COFF style comdats with local keys.
Should fix the sanitizer-windows bot.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254543 91177308-0d34-0410-b5e6-96231b3b80d8
We were failing to copy the fact that the GV is weak and in the case of
an alias, producing invalid IR.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254538 91177308-0d34-0410-b5e6-96231b3b80d8
The linker never takes ownership of a module or changes which module it
is refering to, making it natural to use references.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254449 91177308-0d34-0410-b5e6-96231b3b80d8
It was only used from LTO for a debug feature, and LTO can just create
another linker.
It is pretty odd to have a method to reset the module in the middle of a
link. It would make IdentifiedStructTypes inconsistent with the Module
for example.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254434 91177308-0d34-0410-b5e6-96231b3b80d8
It has to be a bit special because:
* materializeInitFor is not really supposed to call replaceAllUsesWith.
The caller has a plain variable with Dst and expects just the
initializer to be set, not for it to be removed.
* Calling mutateType as we used to do before gets some type
inconsistency which breaks the bitcode writer.
* If linkAppendingVarProto create a dest decl with the correct type to
avoid the above problems, it needs to put the original dst init in
some side table for materializeInitFor to use.
In the end the simplest solution seems to be to just have
linkAppendingVarProto do all the work and set ValueMap[SrcGV to avoid
recursion.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254424 91177308-0d34-0410-b5e6-96231b3b80d8
The difference is that now we don't error on out-of-comdat access to
internal global values. We copy them instead. This seems to match the
expectation of COFF linkers (see pr25686).
Original message:
Start deciding earlier what to link.
A traditional linker is roughly split in symbol resolution and
"copying
stuff".
The two tasks are badly mixed in lib/Linker.
This starts splitting them apart.
With this patch there are no direct call to linkGlobalValueBody or
linkGlobalValueProto. Everything is linked via WapValue.
This also includes a few fixes:
* A GV goes undefined if the comdat is dropped (comdat11.ll).
* We error if an internal GV goes undefined (comdat13.ll).
* We don't link an unused comdat.
The first two match the behavior of an ELF linker. The second one is
equivalent to running globaldce on the input.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254418 91177308-0d34-0410-b5e6-96231b3b80d8
A traditional linker is roughly split in symbol resolution and "copying
stuff".
The two tasks are badly mixed in lib/Linker.
This starts splitting them apart.
With this patch there are no direct call to linkGlobalValueBody or
linkGlobalValueProto. Everything is linked via WapValue.
This also includes a few fixes:
* A GV goes undefined if the comdat is dropped (comdat11.ll).
* We error if an internal GV goes undefined (comdat13.ll).
* We don't link an unused comdat.
The first two match the behavior of an ELF linker. The second one is
equivalent to running globaldce on the input.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254336 91177308-0d34-0410-b5e6-96231b3b80d8
We were not handling the case where an entry must be dropped and the
destination module has no llvm.global_ctors.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254241 91177308-0d34-0410-b5e6-96231b3b80d8
Now the ValueMapper has two callbacks. The first one maps the
declaration. The ValueMapper records the mapping and then materializes
the body/initializer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254209 91177308-0d34-0410-b5e6-96231b3b80d8
They are as much trouble as aliases to declarations. They are requiring
the code generator to define a symbol with the same value as another
symbol, but the second symbol is undefined.
If representing this is important for some optimization, we could add
support for available_externally aliases. They would be *required* to
point to a declaration (or available_externally definition).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254170 91177308-0d34-0410-b5e6-96231b3b80d8
The new function import pass exposed an issue when we import references
to local values on multiple importing passes. They are renamed on each
import pass, and we need to ensure that the already promoted and renamed
references existing in the dest module are correctly identified and
updated so that they aren't spuriously renamed again (due to a perceived
conflict with the newly linked reference).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254009 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The patch to move metadata linking after global value linking didn't
correctly map unmaterialized global values to null as desired. They
were in fact mapped to the source copy. It largely worked by accident
since most module linker clients destroyed the source module which
caused the source GVs to be replaced by null, but caused a failure with
LTO linking on Windows:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312869.html
The problem is that a null return value from materializeValueFor is
handled by mapping the value to self. This is the desired behavior when
materializeValueFor is passed a non-GlobalValue. The problem is how to
distinguish that case from the case where we really do want to map to
null.
This patch addresses this by passing in a new flag to the value mapper
indicating that unmapped global values should be mapped to null. Other
Value types are handled as before.
Note that the documented behavior of asserting on unmapped values when
the flag RF_IgnoreMissingValues isn't set is currently disabled with
FIXME notes due to bootstrap failures. I modified these disabled asserts
so when they are eventually enabled again it won't assert for the
unmapped values when the new RF_NullMapMissingGlobalValues flag is set.
I also considered using a callback into the value materializer, but a
flag seemed cleaner given that there are already existing flags.
I also considered modifying materializeValueFor to return the input
value when we want to map to source and then treat a null return
to mean map to null. However, there are other value materializer
subclasses that implement materializeValueFor, and they would all need
to be audited and the return values possibly changed, which seemed
error-prone.
Reviewers: dexonsmith, joker.eph
Subscribers: pcc, llvm-commits
Differential Revision: http://reviews.llvm.org/D14682
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253170 91177308-0d34-0410-b5e6-96231b3b80d8
