Summary:
We hit undefined references building with ThinLTO when one source file
contained explicit instantiations of a template method (weak_odr) but
there were also implicit instantiations in another file (linkonce_odr),
and the latter was the prevailing copy. In this case the symbol was
marked hidden when the prevailing linkonce_odr copy was promoted to
weak_odr. It led to unsats when the resulting shared library was linked
with other code that contained a reference (expecting to be resolved due
to the explicit instantiation).
Add a CanAutoHide flag to the GV summary to allow the thin link to
identify when all copies are eligible for auto-hiding (because they were
all originally linkonce_odr global unnamed addr), and only do the
auto-hide in that case.
Most of the changes here are due to plumbing the new flag through the
bitcode and llvm assembly, and resulting test changes. I augmented the
existing auto-hide test to check for this situation.
Reviewers: pcc
Subscribers: mehdi_amini, inglorion, eraman, dexonsmith, arphaman, dang, llvm-commits, steven_wu, wmi
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59709
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@360466 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The AliasSummary previously contained the AliaseeGUID, which was only
populated when reading the summary from bitcode. This patch changes it
to instead hold the ValueInfo of the aliasee, and always populates it.
This enables more efficient access to the ValueInfo (specifically in the
recent patch r352438 which needed to perform an index hash table lookup
using the aliasee GUID).
As noted in the comments in AliasSummary, we no longer technically need
to keep a pointer to the corresponding aliasee summary, since it could
be obtained by walking the list of summaries on the ValueInfo looking
for the summary in the same module. However, I am concerned that this
would be inefficient when walking through the index during the thin
link for various analyses. That can be reevaluated in the future.
By always populating this new field, we can remove the guard and special
handling for a 0 aliasee GUID when dumping the dot graph of the summary.
An additional improvement in this patch is when reading the summaries
from LLVM assembly we now set the AliaseeSummary field to the aliasee
summary in that same module, which makes it consistent with the behavior
when reading the summary from bitcode.
Reviewers: pcc, mehdi_amini
Subscribers: inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D57470
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356268 91177308-0d34-0410-b5e6-96231b3b80d8
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351636 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
If LTOUnit splitting is disabled, the module summary analysis computes
the summary information necessary to perform single implementation
devirtualization during the thin link with the index and no IR. The
information collected from the regular LTO IR in the current hybrid WPD
algorithm is summarized, including:
1) For vtable definitions, record the function pointers and their offset
within the vtable initializer (subsumes the information collected from
IR by tryFindVirtualCallTargets).
2) A record for each type metadata summarizing the vtable definitions
decorated with that metadata (subsumes the TypeIdentiferMap collected
from IR).
Also added are the necessary bitcode records, and the corresponding
assembly support.
The index-based WPD will be sent as a follow-on.
Depends on D53890.
Reviewers: pcc
Subscribers: mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D54815
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351453 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Records in the module summary index whether the bitcode was compiled
with the option necessary to enable splitting the LTO unit
(e.g. -fsanitize=cfi, -fwhole-program-vtables, or -fsplit-lto-unit).
The information is passed down to the ModuleSummaryIndex builder via a
new module flag "EnableSplitLTOUnit", which is propagated onto a flag
on the summary index.
This is then used during the LTO link to check whether all linked
summaries were built with the same value of this flag. If not, an error
is issued when we detect a situation requiring whole program visibility
of the class hierarchy. This is the case when both of the following
conditions are met:
1) We are performing LowerTypeTests or Whole Program Devirtualization.
2) There are type tests or type checked loads in the code.
Note I have also changed the ThinLTOBitcodeWriter to also gate the
module splitting on the value of this flag.
Reviewers: pcc
Subscribers: ormris, mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, dang, llvm-commits
Differential Revision: https://reviews.llvm.org/D53890
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350948 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This patch computes the synthetic function entry count on the whole
program callgraph (based on module summary) and writes the entry counts
to the summary. After function importing, this count gets attached to
the IR as metadata. Since it adds a new field to the summary, this bumps
up the version.
Reviewers: tejohnson
Subscribers: mehdi_amini, inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D43521
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349076 91177308-0d34-0410-b5e6-96231b3b80d8
`Saver` is a StringSaver, which has a few overloads of `save` that all
ultimately just call `StringRef save(StringRef)`. Just take a StringRef
here instead of building up a std::string to convert it to a StringRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348650 91177308-0d34-0410-b5e6-96231b3b80d8
An attempt to recommit r346584 after failure on OSX build bot.
Fixed cache key computation in ThinLTOCodeGenerator and added
test case
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347033 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The NotEligibleToImport flag on the GlobalValueSummary was set if it
isn't legal to import (e.g. because it references unpromotable locals)
and when it can't be inlined (in which case importing is pointless).
I split out the inlinable piece into a separate flag on the
FunctionSummary (doesn't make sense for aliases or global variables),
because in the future we may want to import for reasons other than
inlining.
Reviewers: davidxl
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53345
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346261 91177308-0d34-0410-b5e6-96231b3b80d8
ModuleSummaryIndex::exportToDot crashes when linking the Linux kernel
under ThinLTO using LLVMgold.so. This is due to the exportToDot
function trying to get the GUID of an empty ValueInfo. The root cause
related to the fact that we attempt to get the GUID of an aliasee
via its OriginalGUID recorded in the aliasee summary, and that is not
always possible. Specifically, we cannot do this mapping when the value
is internal linkage and there were other internal linkage symbols with
the same name.
There are 2 fixes for the problem included here.
1) In all cases where we can currently print the dot file from the
command line (which is only via save-temps), we have a valid AliaseeGUID
in the AliasSummary. Use that when it is available, so that we can get
the correct aliasee GUID whenever possible.
2) However, if we were to invoke exportToDot from the debugger right
after it is built during the initial analysis step (i.e. the per-module
summary), we won't have the AliaseeGUID field populated. In that case,
we have a fallback fix that will simply print "@"+GUID when we aren't
able to get the GUID from the OriginalGUID. It simply checks if the VI
is valid or not before attempting to get the name. Additionally, since
getAliaseeGUID will assert that the AliaseeGUID is non-zero, guard the
earlier fix#1 by a new function hasAliaseeGUID().
Reviewers: pcc, tmroeder
Subscribers: evgeny777, mehdi_amini, inglorion, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53986
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346055 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
In D49565/r337503, the type id record writing was fixed so that only
referenced type ids were emitted into each per-module index for ThinLTO
distributed builds. However, this still left an efficiency issue: each
per-module index checked all type ids for membership in the referenced
set, yielding O(M*N) performance (M indexes and N type ids).
Change the TypeIdMap in the summary to be indexed by GUID, to facilitate
correlating with type identifier GUIDs referenced in the function
summary TypeIdInfo structures. This allowed simplifying other
places where a map from type id GUID to type id map entry was previously
being used to aid this correlation.
Also fix AsmWriter code to handle the rare case of type id GUID
collision.
For a large internal application, this reduced the thin link time by
almost 15%.
Reviewers: pcc, vitalybuka
Subscribers: mehdi_amini, inglorion, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51330
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343021 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Adds the option for the printing of summary information about functions
considered but rejected for importing during the thin link.
Reviewers: davidxl
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D50881
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340047 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Rather than just print the GUID, when it is available in the index,
print the global name as well in the function import thin link debug
messages. Names will be available when the combined index is being
built by the same process, e.g. a linker or "llvm-lto2 run".
Reviewers: davidxl
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, llvm-commits
Differential Revision: https://reviews.llvm.org/D48612
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335760 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Adds assembly parsing support for the module summary index (follow on
to r333335 which added the assembly writing support).
I added support to llvm-as to invoke the index parsing, so that it can
create either a bitcode file with a Module and a per-module index, or
a combined index without a Module.
I will send follow on patches soon to do the following:
- add support to tools such as llvm-lto2 to parse the per-module indexes
from assembly instead of bitcode when testing the thin link.
- verification support.
Depends on D47844 and D47842.
Reviewers: pcc, dexonsmith, mehdi_amini
Subscribers: inglorion, eraman, steven_wu, llvm-commits
Differential Revision: https://reviews.llvm.org/D47905
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335602 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Adds a string saver to the ModuleSummaryIndex so it can store value
names in the case of adding a ValueInfo for a GUID when we don't
have the name stored in a Module string table. This is motivated
by the upcoming summary parser patch, where we will read value names
from the summary entry and want to store them, even when a Module
is not available.
Currently this allows us to store the name in the legacy bitcode case,
and I have added a test to show that.
Reviewers: pcc, dexonsmith
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, llvm-commits
Differential Revision: https://reviews.llvm.org/D47842
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335570 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Without this change we only add module paths to the combined index when
there is a module hash or at least one global value. Make this more
consistent by adding the module to the index whenever there is a summary
section, and it is a per-module summary (had a MODULE_CODE_SOURCE_FILENAME
record).
Since we will no longer add module paths lazily, add a new interface to get
the module info from the index that asserts it is already added.
Fixes PR37899.
Reviewers: Vlad, pcc
Subscribers: mehdi_amini, inglorion, steven_wu, llvm-commits
Differential Revision: https://reviews.llvm.org/D48511
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335567 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
I discovered when writing the summary parsing support that the
per-module index builder and writer are computing the GUID from the
value name alone (ignoring the linkage type). This was ok since those
GUID were not emitted in the bitcode, and there are never multiple
conflicting names in a single module.
However, I don't see a reason for making the GUID computation different
for the per-module case. It also makes things simpler on the parsing
side to have the GUID computation consistent. So this patch changes the
summary analysis phase and the per-module summary writer to compute the
GUID using the facility on the GlobalValue.
Reviewers: pcc, dexonsmith
Subscribers: llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D47844
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335560 91177308-0d34-0410-b5e6-96231b3b80d8
With the upcoming patch to add summary parsing support, IsAnalysis would
be true in contexts where we are not performing module summary analysis.
Rename to the more specific and approprate HaveGVs, which is essentially
what this flag is indicating.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334140 91177308-0d34-0410-b5e6-96231b3b80d8
Compare Ref pointers instead of GUID, to handle comparison with special
empty/tombstone ValueInfo. This was already done for operator==, to
support inserting ValueInfo into DenseMap, but I need the operator!=
side change for upcoming AsmParser summary parsing support.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334111 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Implements AsmWriter support for printing the module summary index to
assembly with the format discussed in the RFC "LLVM Assembly format for
ThinLTO Summary".
Implements just enough of the parsing support to recognize and ignore
the summary entries. As agreed in the RFC thread, this will be the
behavior when assembling the IR. A follow on change will implement
parsing/assembling of the summary entries for use by tools that
currently build the summary index from bitcode.
Reviewers: dexonsmith, pcc
Subscribers: inglorion, eraman, steven_wu, dblaikie, llvm-commits
Differential Revision: https://reviews.llvm.org/D46699
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333335 91177308-0d34-0410-b5e6-96231b3b80d8
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
Differential Revision: https://reviews.llvm.org/D46290
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331272 91177308-0d34-0410-b5e6-96231b3b80d8
The retpoline mitigation for variant 2 of CVE-2017-5715 inhibits the
branch predictor, and as a result it can lead to a measurable loss of
performance. We can reduce the performance impact of retpolined virtual
calls by replacing them with a special construct known as a branch
funnel, which is an instruction sequence that implements virtual calls
to a set of known targets using a binary tree of direct branches. This
allows the processor to speculately execute valid implementations of the
virtual function without allowing for speculative execution of of calls
to arbitrary addresses.
This patch extends the whole-program devirtualization pass to replace
certain virtual calls with calls to branch funnels, which are
represented using a new llvm.icall.jumptable intrinsic. It also extends
the LowerTypeTests pass to recognize the new intrinsic, generate code
for the branch funnels (x86_64 only for now) and lay out virtual tables
as required for each branch funnel.
The implementation supports full LTO as well as ThinLTO, and extends the
ThinLTO summary format used for whole-program devirtualization to
support branch funnels.
For more details see RFC:
http://lists.llvm.org/pipermail/llvm-dev/2018-January/120672.html
Differential Revision: https://reviews.llvm.org/D42453
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327163 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The current integer representation of relative block frequency prevents
representing relative block frequencies below 1. This change uses a 8 of
the 29 bits to represent the decimal part by using a fixed scale of -8.
Reviewers: tejohnson, davidxl
Subscribers: mehdi_amini, inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D43520
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325823 91177308-0d34-0410-b5e6-96231b3b80d8
Add GraphTraits definitions to the FunctionSummary and ModuleSummaryIndex classes. These GraphTraits will be used to construct find SCC's in ThinLTO analysis passes.
Third attempt - moved function from lambda to static function due to build failures.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325506 91177308-0d34-0410-b5e6-96231b3b80d8
Add GraphTraits definitions to the FunctionSummary and ModuleSummaryIndex classes. These GraphTraits will be used to construct find SCC's in ThinLTO analysis passes.
Second attempt, since last patch caused stage2 build to fail (now using function_ref rather than std::function).
Reverted due to buildbot failures
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325454 91177308-0d34-0410-b5e6-96231b3b80d8
Add GraphTraits definitions to the FunctionSummary and ModuleSummaryIndex classes. These GraphTraits will be used to construct find SCC's in ThinLTO analysis passes.
Second attempt, since last patch caused stage2 build to fail (now using function_ref rather than std::function).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325448 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Gold plugin does not add pass to ThinLTO modules without useful symbols.
In this case ThinLTO can't create corresponding index file and some features, like CFI,
cannot be processes by backed correctly without index.
Given that we don't need the backed output we can request it to avoid
processing the module. This is implemented by this patch using new
"SkipModuleByDistributedBackend" flag.
Reviewers: pcc, tejohnson
Subscribers: mehdi_amini, inglorion, eraman, cfe-commits
Differential Revision: https://reviews.llvm.org/D42995
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325411 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
TypeID summaries are used by CFI and need to be serialized by ThinLTO
indexing for later use by LTO Backend.
Reviewers: tejohnson, pcc
Subscribers: mehdi_amini, inglorion, eraman, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D42611
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325182 91177308-0d34-0410-b5e6-96231b3b80d8
It caused assertion failure
Assertion failed: (!DD.IsLambda && !MergeDD.IsLambda && "faked up lambda definition?"), function MergeDefinitionData, file /Users/buildslave/jenkins/workspace/clang-stage1-configure-RA/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp, line 1675.
on the second stage build bots.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@324932 91177308-0d34-0410-b5e6-96231b3b80d8
Add GraphTraits definitions to the FunctionSummary and ModuleSummaryIndex classes. These GraphTraits will be used to construct find SCC's in ThinLTO analysis passes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@324854 91177308-0d34-0410-b5e6-96231b3b80d8
It was reverted after buildbot regressions.
Original commit message:
This allows relative block frequency of call edges to be passed
to the thinlink stage where it will be used to compute synthetic
entry counts of functions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323460 91177308-0d34-0410-b5e6-96231b3b80d8
computeDeadSymbols accessed isLive() which was not public
before. It does not make much sence to keep isLive() private
because flags are available via flags() public member anyways.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323415 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This allows relative block frequency of call edges to be passed to the
thinlink stage where it will be used to compute synthetic entry counts
of functions.
Reviewers: tejohnson, pcc
Subscribers: mehdi_amini, llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D42212
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323349 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This implements a missing feature to allow importing of aliases, which
was previously disabled because alias cannot be available_externally.
We instead import an alias as a copy of its aliasee.
Some additional work was required in the IndexBitcodeWriter for the
distributed build case, to ensure that the aliasee has a value id
in the distributed index file (i.e. even when it is not being
imported directly).
This is a performance win in codes that have many aliases, e.g. C++
applications that have many constructor and destructor aliases.
Reviewers: pcc
Subscribers: mehdi_amini, inglorion, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D40747
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320895 91177308-0d34-0410-b5e6-96231b3b80d8
Now that we have a way to mark GlobalValues as local we can use the symbol
resolutions that the linker plugin provides as part of lto/thinlto link
step to refine the compilers view on what symbols will end up being local.
Originally commited as r317374, but reverted in r317395 to update some missed
tests.
Differential Revision: https://reviews.llvm.org/D35702
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317408 91177308-0d34-0410-b5e6-96231b3b80d8
