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.
llvm-svn: 264288
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.
llvm-svn: 264223
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.
llvm-svn: 264192
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.
llvm-svn: 264103
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>
llvm-svn: 263863
(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.
llvm-svn: 263513
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.
llvm-svn: 263490
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
llvm-svn: 263143
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
llvm-svn: 260395
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
llvm-svn: 260122
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.
llvm-svn: 259049
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
llvm-svn: 258861
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.
llvm-svn: 258728
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
llvm-svn: 258458
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.
llvm-svn: 258355
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.
llvm-svn: 257420
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.
llvm-svn: 257181
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
llvm-svn: 257174
Follow-up to r257000: DIImportedEntity can reach a DISubprogram via
its entity, but also via its scope. Handle the latter case as well.
PR26037.
llvm-svn: 257019
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.
llvm-svn: 257000
As suggested in review for r255909, rename MDMaterialized to AllowTemps,
and identify the name of the boolean flag being set in calls to
saveMetadataList.
llvm-svn: 256653
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.
llvm-svn: 256648
Renamed variables to be more reflective of whether they are
an instance of Linker, IRLinker or ModuleLinker. Also fix a stale
comment.
llvm-svn: 256011
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
llvm-svn: 256003
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
llvm-svn: 255909
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.
llvm-svn: 255571
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.
llvm-svn: 255254
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.
llvm-svn: 254907
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.
llvm-svn: 254777
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
llvm-svn: 254624
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>
llvm-svn: 254581
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.
llvm-svn: 254559
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.
llvm-svn: 254556
For efficiency reason, when importing multiple functions for the same Module,
we can avoid reparsing it every time.
Differential Revision: http://reviews.llvm.org/D15102
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 254486
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.
llvm-svn: 254434
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.
llvm-svn: 254424
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.
llvm-svn: 254418
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.
llvm-svn: 254336
Now the ValueMapper has two callbacks. The first one maps the
declaration. The ValueMapper records the mapping and then materializes
the body/initializer.
llvm-svn: 254209
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).
llvm-svn: 254170
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).
llvm-svn: 254009
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
llvm-svn: 253170
Summary:
The module linker lazy links some "discardable if unused" global
values (e.g. linkonce), materializing and linking them only
if they are referenced in the module. If a comdat group contains a
linkonce member that is not referenced, however, it would not be
materialized and linked, leading to an incomplete comdat group.
If there are other object files not part of the same LTO link that also
define and use that comdat group, the linker may select the incomplete
group leading to link time unsats.
To solve this, whenever a global value body is linked, make sure we
materialize any other members of the same comdat group that are not yet
materialized. This ensures they are in the lazy link list and get linked
as well.
Added new test and adjusted old test to remove parts that didn't
make sense with fix.
Reviewers: rafael
Subscribers: dexonsmith, davidxl, llvm-commits
Differential Revision: http://reviews.llvm.org/D14516
llvm-svn: 252647
Ensure WeakAny variables are imported as ExternalWeak declarations. To
handle WeakAny more consistently and fix this issue:
1) Update helper doImportAsDefinition to properly flag WeakAny variables
and aliases as not importing defintions.
Update callers of doImportAsDefinition to remove now redundant checks for
WeakAny aliases, or ignore aliases, as appropriate.
2) Add any !doImportAsDefinition GVs to DoNotLinkFromSource set during
linking of the GV prototype, where we usually add GVs to the
DoNotLinkFromSource set for other reasons.
Remove now unnecessary adding of WeakAny aliases to
DoNotLinkFromSource set from copyGlobalAliasProto.
Remove now unnecessary guard against linking non-imported function
bodies from ModuleLinker::run.
llvm-svn: 252626
Summary:
This reverts commit r251965.
Restore "Move metadata linking after lazy global materialization/linking."
This restores commit r251926, with fixes for the LTO bootstrapping bot
failure.
The bot failure was caused by references from debug metadata to
otherwise unreferenced globals. Previously, this caused the lazy linking
to link in their defs, which is unnecessary. With this patch, because
lazy linking is complete when we encounter the metadata reference, the
materializer created a declaration. For definitions such as aliases and
comdats, it is illegal to have a declaration. Furthermore, metadata
linking should not change code generation. Therefore, when linking of
global value bodies is complete, the materializer will simply return
nullptr as the new reference for the linked metadata.
This change required fixing a different test to ensure there was a
real reference to a linkonce global that was only being reference from
metadata.
Note that the new changes to the only-needed-named-metadata.ll test
illustrate an issue with llvm-link -only-needed handling of comdat
groups, whereby it may result in an incomplete comdat group. I note this
in the test comments, but the issue is orthogonal to this patch (it can
be reproduced without any metadata at head).
Reviewers: dexonsmith, rafael, tra
Subscribers: tobiasvk, joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D14447
llvm-svn: 252320
Previously, subprograms contained a metadata reference to the function they
described. Because most clients need to get or set a subprogram for a given
function rather than the other way around, this created unneeded inefficiency.
For example, many passes needed to call the function llvm::makeSubprogramMap()
to build a mapping from functions to subprograms, and the IR linker needed to
fix up function references in a way that caused quadratic complexity in the IR
linking phase of LTO.
This change reverses the direction of the edge by storing the subprogram as
function-level metadata and removing DISubprogram's function field.
Since this is an IR change, a bitcode upgrade has been provided.
Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is
attached to the PR.
Differential Revision: http://reviews.llvm.org/D14265
llvm-svn: 252219
When converting an alias to a non-alias when the aliasee is not
imported, ensure that the linkage type is set to external so that it is
a valid linkage type. Added a test case that exposed this issue.
llvm-svn: 252054
This reverts commit r251926. I believe this is causing an LTO
bootstrapping bot failure
(http://lab.llvm.org:8080/green/job/llvm-stage2-cmake-RgLTO_build/3669/).
Haven't been able to repro it yet, but after looking at the metadata I
am pretty sure I know what is going on.
llvm-svn: 251965
Summary:
Currently, named metadata is linked before the LazilyLinkGlobalValues
list is walked and materialized/linked. As a result, references
from DISubprogram and DIGlobalVariable metadata to yet unmaterialized
functions and variables cause them to be added to the lazy linking
list and their definitions are materialized and linked.
This makes the llvm-link -only-needed option not have the intended
effect when debug information is present, as the otherwise unneeded
functions/variables are still linked in.
Additionally, for ThinLTO I have implemented a mechanism to only link
in debug metadata needed by imported functions. Moving named metadata
linking after lazy GV linking will facilitate applying this mechanism
to the LTO and "llvm-link -only-needed" cases as well.
Reviewers: dexonsmith, tra, dblaikie
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14195
llvm-svn: 251926
Rafael Espindola