[ThinLTO] Add Visibility bits to GlobalValueSummary::GVFlags

Imported functions and variable get the visibility from the module supplying the
definition. However, non-imported definitions do not ge

[ThinLTO] Add Visibility bits to GlobalValueSummary::GVFlags

Imported functions and variable get the visibility from the module supplying the
definition. However, non-imported definitions do not get the visibility from
(ELF) the most constraining visibility among all modules (Mach-O) the visibility
of the prevailing definition.

This patch

* adds visibility bits to GlobalValueSummary::GVFlags
* computes the result visibility and propagates it to all definitions

Protected/hidden can imply dso_local which can enable some optimizations (this
is stronger than GVFlags::DSOLocal because the implied dso_local can be
leveraged for ELF -shared while default visibility dso_local has to be cleared
for ELF -shared).

Note: we don't have summaries for declarations, so for ELF if a declaration has
the most constraining visibility, the result visibility may not be that one.

Differential Revision: https://reviews.llvm.org/D92900

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[ThinLTO] Compute the basic block count across modules.

Summary:
Count the per-module number of basic blocks when the module summary is computed
and sum them up during Thin LTO indexing.

This is us

[ThinLTO] Compute the basic block count across modules.

Summary:
Count the per-module number of basic blocks when the module summary is computed
and sum them up during Thin LTO indexing.

This is used to estimate the working set size under the partial sample PGO.

This is split off of D79831.

Reviewers: davidxl, espindola

Subscribers: emaste, inglorion, hiraditya, MaskRay, steven_wu, dexonsmith, arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80403

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[ThinLTO] Attempt to recommit r365188 after alignment fix

llvm-svn: 365215

Reverted r365188 due to alignment problems on i686-android

llvm-svn: 365206

[ThinLTO] Attempt to recommit r365040 after caching fix

It's possible that some function can load and store the same
variable using the same constant expression:

store %Derived* @foo, %Derived** bi

[ThinLTO] Attempt to recommit r365040 after caching fix

It's possible that some function can load and store the same
variable using the same constant expression:

store %Derived* @foo, %Derived** bitcast (%Base** @bar to %Derived**)
%42 = load %Derived*, %Derived** bitcast (%Base** @bar to %Derived**)

The bitcast expression was mistakenly cached while processing loads,
and never examined later when processing store. This caused @bar to
be mistakenly treated as read-only variable. See load-store-caching.ll.

llvm-svn: 365188

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Revert [ThinLTO] Optimize writeonly globals out

This reverts r365040 (git commit 5cacb914758c7f436b47c8362100f10cef14bbc4)

Speculatively reverting, since this appears to have broken check-lld on
Li

Revert [ThinLTO] Optimize writeonly globals out

This reverts r365040 (git commit 5cacb914758c7f436b47c8362100f10cef14bbc4)

Speculatively reverting, since this appears to have broken check-lld on
Linux. Partial analysis in https://crbug.com/981168.

llvm-svn: 365097

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[ThinLTO] Optimize writeonly globals out

Differential revision: https://reviews.llvm.org/D63444

llvm-svn: 365040

[ThinLTO] Auto-hide prevailing linkonce_odr only when all copies eligible

Summary:
We hit undefined references building with ThinLTO when one source file
contained explicit instantiations of a templ

[ThinLTO] Auto-hide prevailing linkonce_odr only when all copies eligible

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

llvm-svn: 360466

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[LTO] Record whether LTOUnit splitting is enabled in index

Summary:
Records in the module summary index whether the bitcode was compiled
with the option necessary to enable splitting the LTO unit
(e

[LTO] Record whether LTOUnit splitting is enabled in index

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

llvm-svn: 350948

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[ThinLTO] Compute synthetic function entry count

Summary:
This patch computes the synthetic function entry count on the whole
program callgraph (based on module summary) and writes the entry counts

[ThinLTO] Compute synthetic function entry count

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

llvm-svn: 349076

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[ThinLTO] Internalize readonly globals

An attempt to recommit r346584 after failure on OSX build bot.
Fixed cache key computation in ThinLTOCodeGenerator and added
test case

llvm-svn: 347033

Revert "[ThinLTO] Internalize readonly globals"

This reverts commit 10c84a8f35cae4a9fc421648d9608fccda3925f2.

llvm-svn: 346768

[ThinLTO] Internalize readonly globals

This patch allows internalising globals if all accesses to them
(from live functions) are from non-volatile load instructions

Differential revision: https://r

[ThinLTO] Internalize readonly globals

This patch allows internalising globals if all accesses to them
(from live functions) are from non-volatile load instructions

Differential revision: https://reviews.llvm.org/D49362

llvm-svn: 346584

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[ThinLTO] Parse module summary index from assembly

Summary:
Adds assembly parsing support for the module summary index (follow on
to r333335 which added the assembly writing support).

I added suppo

[ThinLTO] Parse module summary index from assembly

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

llvm-svn: 335602

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[ThinLTO] Fix a few more test match issues

Fix a few more bot failures due to r333335:
- don't match path other than file name, since the delimiter is
different for Windows
- The summary IDs in thin

[ThinLTO] Fix a few more test match issues

Fix a few more bot failures due to r333335:
- don't match path other than file name, since the delimiter is
different for Windows
- The summary IDs in thinlto-function-summary-refgraph.ll may vary
and therefore can't be matched exactly, because the ordering depends
on the iteration order of the index map which is keyed by GUID. The GUID
for private values will depend on the path.

llvm-svn: 333338

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[ThinLTO] Print module summary index to assembly

Summary:
Implements AsmWriter support for printing the module summary index to
assembly with the format discussed in the RFC "LLVM Assembly format fo

[ThinLTO] Print module summary index to assembly

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

llvm-svn: 333335

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[ThinLTO] Serialize WithGlobalValueDeadStripping index flag for distributed backends

Summary:
A recent fix to drop dead symbols (r323633) did not work for ThinLTO
distributed backends because we los

[ThinLTO] Serialize WithGlobalValueDeadStripping index flag for distributed backends

Summary:
A recent fix to drop dead symbols (r323633) did not work for ThinLTO
distributed backends because we lose the WithGlobalValueDeadStripping
set on the index during the thin link. This patch adds a new flags
record to the bitcode format for the index, and serializes this flag
for the combined index (it would always be 0 for the per-module index
generated by the compile step, so no need to serialize the new flags
record there until/unless we add another flag that applies to the
per-module indexes).

Generally this flag should always be set for the distributed backends,
which are necessarily performed after the thin link. However, if we were
to simply set this flag on the index applied to the distributed backends
(invoked via clang), we would lose the ability to disable dead stripping
via -compute-dead=false for debugging purposes.

Reviewers: grimar, pcc

Subscribers: mehdi_amini, inglorion, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D42799

llvm-svn: 324444

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[ThinLTO] Add FunctionAttrs to ThinLTO index

Adds function attributes to index: ReadNone, ReadOnly, NoRecurse, NoAlias. This attributes will be used for future ThinLTO optimizations that will propag

[ThinLTO] Add FunctionAttrs to ThinLTO index

Adds function attributes to index: ReadNone, ReadOnly, NoRecurse, NoAlias. This attributes will be used for future ThinLTO optimizations that will propagate function attributes across modules.

llvm-svn: 310061

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Increase the import-threshold for crtical functions.

Summary: For interative sample-pgo, if a hot call site is inlined in the profiling binary, we should inline it in before profile annotation in th

Increase the import-threshold for crtical functions.

Summary: For interative sample-pgo, if a hot call site is inlined in the profiling binary, we should inline it in before profile annotation in the backend. Before that, the compile phase first collects all GUIDs that needs to be imported and creates virtual "hot" call edge in the summary. However, "hot" is not good enough to guarantee the callsites get inlined. This patch introduces "critical" call edge, and assign much higher importing threshold for those edges.

Reviewers: tejohnson

Reviewed By: tejohnson

Subscribers: sanjoy, mehdi_amini, llvm-commits, eraman

Differential Revision: https://reviews.llvm.org/D35096

llvm-svn: 307439

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Bitcode: Write the irsymtab to disk.

Differential Revision: https://reviews.llvm.org/D33973

llvm-svn: 306487

Restrict call metadata based hotness detection to Sample PGO mode

Summary:
Don't use the metadata on call instructions for determining hotness
unless we are in sample PGO mode, where it is needed be

Restrict call metadata based hotness detection to Sample PGO mode

Summary:
Don't use the metadata on call instructions for determining hotness
unless we are in sample PGO mode, where it is needed because profile
counts are not accurate. In instrumentation mode this is not necessary
and does more harm than good when calls have VP metadata that hasn't
been properly scaled after transformations or dropped after constant
prop based devirtualization (both should be fixed, but we don't need
to do this in the first place for instrumentation PGO).

This required adjusting a number of tests to distinguish between sample
and instrumentation PGO handling, and to add in profile summary metadata
so that getProfileCount can get the summary.

Reviewers: davidxl, danielcdh

Subscribers: aemerson, rengolin, mehdi_amini, Prazek, llvm-commits

Differential Revision: https://reviews.llvm.org/D32877

llvm-svn: 302844

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Bitcode: Add a string table to the bitcode format.

Add a top-level STRTAB block containing a string table blob, and start storing
strings for module codes FUNCTION, GLOBALVAR, ALIAS, IFUNC and COMDA

Bitcode: Add a string table to the bitcode format.

Add a top-level STRTAB block containing a string table blob, and start storing
strings for module codes FUNCTION, GLOBALVAR, ALIAS, IFUNC and COMDAT in
the string table.

This change allows us to share names between globals and comdats as well
as between modules, and improves the efficiency of loading bitcode files by
no longer using a bit encoding for symbol names. Once we start writing the
irsymtab to the bitcode file we will also be able to share strings between
it and the module.

On my machine, link time for Chromium for Linux with ThinLTO decreases by
about 7% for no-op incremental builds or about 1% for full builds. Total
bitcode file size decreases by about 3%.

As discussed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2017-April/111732.html

Differential Revision: https://reviews.llvm.org/D31838

llvm-svn: 300464

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Use ProfileSummary:getProfileCount to get ScaledCount for ModuleSummary

Summary: ModuleSummary should use the standard interface of ProfileSummary::getProfileCount.

Reviewers: eraman, tejohnson

Re

Use ProfileSummary:getProfileCount to get ScaledCount for ModuleSummary

Summary: ModuleSummary should use the standard interface of ProfileSummary::getProfileCount.

Reviewers: eraman, tejohnson

Reviewed By: tejohnson

Subscribers: tejohnson, mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D31154

llvm-svn: 298404

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Add function importing info from samplepgo profile to the module summary.

Summary: For SamplePGO, the profile may contain cross-module inline stacks. As we need to make sure the profile annotation h

Add function importing info from samplepgo profile to the module summary.

Summary: For SamplePGO, the profile may contain cross-module inline stacks. As we need to make sure the profile annotation happens when all the hot inline stacks are expanded, we need to pass this info to the module importer so that it can import proper functions if necessary. This patch implemented this feature by emitting cross-module targets as part of function entry metadata. In the module-summary phase, the metadata is used to build call edges that points to functions need to be imported.

Reviewers: mehdi_amini, tejohnson

Reviewed By: tejohnson

Subscribers: davidxl, llvm-commits

Differential Revision: https://reviews.llvm.org/D30053

llvm-svn: 296498

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IR: Eliminate non-determinism in the module summary analysis.

Also make the summary ref and call graph vectors immutable. This means
a smaller API surface and fewer places to audit for non-determini

IR: Eliminate non-determinism in the module summary analysis.

Also make the summary ref and call graph vectors immutable. This means
a smaller API surface and fewer places to audit for non-determinism.

Differential Revision: https://reviews.llvm.org/D27875

llvm-svn: 290200

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