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Commit Graph

272 Commits

Author SHA1 Message Date
evgeny
3ab27f6ce8 [ThinLTO] Add correctness check for RO/WO variable import
This patch adds an assertion check for exported read/write-only
variables to be also in import list for module. If they aren't
we may face linker errors, because read/write-only variables are
internalized in their source modules. The patch also changes
export lists to store ValueInfo instead of GUID for performance
considerations.

Differential revision: https://reviews.llvm.org/D70128
2019-11-14 12:24:05 +03:00
Reid Kleckner
3f676674e7 Move CodeGenFileType enum to Support/CodeGen.h
Avoids the need to include TargetMachine.h from various places just for
an enum. Various other enums live here, such as the optimization level,
TLS model, etc. Data suggests that this change probably doesn't matter,
but it seems nice to have anyway.
2019-11-13 16:39:34 -08:00
Guillaume Chatelet
89f87ca322 [Alignment][NFC] Remove dependency on GlobalObject::setAlignment(unsigned)
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: arsenm, mehdi_amini, jvesely, nhaehnle, hiraditya, steven_wu, dexonsmith, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68944

llvm-svn: 374880
2019-10-15 11:24:36 +00:00
Jordan Rose
fa21e7962b ADT: Save a word in every StringSet entry
Add a specialization to StringMap (actually StringMapEntry) for a
value type of NoneType (the type of llvm::None), and use it for
StringSet. This'll save us a word from every entry in a StringSet,
used for alignment with the size_t that stores the string length.

I could have gone all the way to some kind of empty base class
optimization, but that seemed like overkill. Someone can consider
adding that in the future, though.

https://reviews.llvm.org/D68586

llvm-svn: 374440
2019-10-10 20:22:53 +00:00
Steven Wu
7fb3882581 [LTO][Legacy] Add new C inferface to query libcall functions
Summary:
This is needed to implemented the same approach as lld (implemented in r338434)
for how to handling symbols that can be generated by LTO code generator
but not present in the symbol table for linker that uses legacy C APIs.

libLTO is in charge of providing the list of symbols. Linker is in
charge of implementing the eager loading from static libraries using
the list of symbols.

rdar://problem/52853974

Reviewers: tejohnson, bd1976llvm, deadalnix, espindola

Reviewed By: tejohnson

Subscribers: emaste, arichardson, hiraditya, MaskRay, dang, kledzik, mehdi_amini, inglorion, jkorous, dexonsmith, ributzka, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67568

llvm-svn: 372021
2019-09-16 18:49:54 +00:00
Teresa Johnson
c649b1f9bb [ThinLTO] Fix handling of weak interposable symbols
Summary:
Keep aliasees alive if their alias is live, otherwise we end up with an
alias to a declaration, which is invalid. This can happen when the
aliasee is weak and non-prevailing.

This fix exposed the fact that we were then attempting to internalize
the weak symbol, which was not exported as it was not prevailing. We
should not internalize interposable symbols in general, unless this is
the prevailing copy, since it can lead to incorrect inlining and other
optimizations. Most of the changes in this patch are due to the
restructuring required to pass down the prevailing callback.

Finally, while implementing the test cases, I found that in the case of
a weak aliasee that is still marked not live because its alias isn't
live, after dropping the definition we incorrectly marked the
declaration with weak linkage when resolving prevailing symbols in the
module. This was due to some special case handling for symbols marked
WeakLinkage in the summary located before instead of after a subsequent
check for the symbol being a declaration. It turns out that we don't
actually need this special case handling any more (looking back at the
history, when that was added the code was structured quite differently)
- we will correctly mark with weak linkage further below when the
definition hasn't been dropped.

Fixes PR42542.

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, steven_wu, dexonsmith, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66264

llvm-svn: 369766
2019-08-23 15:18:58 +00:00
Jonas Devlieghere
2c693415b7 [llvm] Migrate llvm::make_unique to std::make_unique
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.

llvm-svn: 369013
2019-08-15 15:54:37 +00:00
Francis Visoiu Mistrih
1e67de55c2 [Remarks] Extend -fsave-optimization-record to specify the format
Use -fsave-optimization-record=<format> to specify a different format
than the default, which is YAML.

For now, only YAML is supported.

llvm-svn: 363573
2019-06-17 16:06:00 +00:00
Aaron Puchert
148bc13d52 [Clang] Harmonize Split DWARF options with llc
Summary:
With Split DWARF the resulting object file (then called skeleton CU)
contains the file name of another ("DWO") file with the debug info.
This can be a problem for remote compilation, as it will contain the
name of the file on the compilation server, not on the client.

To use Split DWARF with remote compilation, one needs to either

* make sure only relative paths are used, and mirror the build directory
  structure of the client on the server,
* inject the desired file name on the client directly.

Since llc already supports the latter solution, we're just copying that
over. We allow setting the actual output filename separately from the
value of the DW_AT_[GNU_]dwo_name attribute in the skeleton CU.

Fixes PR40276.

Reviewers: dblaikie, echristo, tejohnson

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D59673

llvm-svn: 363496
2019-06-15 15:38:51 +00:00
Francis Visoiu Mistrih
cb1a2a8d0d Reland: [Remarks] Refactor optimization remarks setup
* Add a common function to setup opt-remarks
* Rename common options to the same names
* Add error types to distinguish between file errors and regex errors

llvm-svn: 363415
2019-06-14 16:20:51 +00:00
Francis Visoiu Mistrih
1af0ed9ddc Revert "[Remarks] Refactor optimization remarks setup"
This reverts commit 6e6e3af55bb97e1a4c97375c15a2b0099120c5a7.

This breaks greendragon.

llvm-svn: 363343
2019-06-14 00:05:56 +00:00
Francis Visoiu Mistrih
ad3951fe7a [Remarks] Refactor optimization remarks setup
* Add a common function to setup opt-remarks
* Rename common options to the same names
* Add error types to distinguish between file errors and regex errors

llvm-svn: 363328
2019-06-13 21:46:57 +00:00
Ben Dunbobbin
33ef399ccf [ThinLTO]LTO]Legacy] Fix dependent libraries support by adding querying of the IRSymtab
Dependent libraries support for the legacy api was committed in a
broken state (see: https://reviews.llvm.org/D60274). This was missed
due to the painful nature of having to integrate the changes into a
linker in order to test. This change implements support for dependent
libraries in the legacy LTO api:

- I have removed the current api function, which returns a single
string, and   added functions to access each dependent library
specifier individually.

- To reduce the testing pain, I have made the api functions as thin as
possible to   maximize coverage from llvm-lto.

- When doing ThinLTO the system linker will load the modules lazily
when scanning   the input files. Unfortunately, when modules are
lazily loaded there is no access   to module level named metadata. To
fix this I have added api functions that allow   querying the IRSymtab
for the dependent libraries. I hope to expand the api in the   future
so that, eventually, all the information needed by a client linker
during   scan can be retrieved from the IRSymtab.

Differential Revision: https://reviews.llvm.org/D62935

llvm-svn: 363140
2019-06-12 11:07:56 +00:00
Ben Dunbobbin
2aa2767ebe [ELF] Implement Dependent Libraries Feature
This patch implements a limited form of autolinking primarily designed to allow
either the --dependent-library compiler option, or "comment lib" pragmas (
https://docs.microsoft.com/en-us/cpp/preprocessor/comment-c-cpp?view=vs-2017) in
C/C++ e.g. #pragma comment(lib, "foo"), to cause an ELF linker to automatically
add the specified library to the link when processing the input file generated
by the compiler.

Currently this extension is unique to LLVM and LLD. However, care has been taken
to design this feature so that it could be supported by other ELF linkers.

The design goals were to provide:

- A simple linking model for developers to reason about.
- The ability to to override autolinking from the linker command line.
- Source code compatibility, where possible, with "comment lib" pragmas in other
  environments (MSVC in particular).

Dependent library support is implemented differently for ELF platforms than on
the other platforms. Primarily this difference is that on ELF we pass the
dependent library specifiers directly to the linker without manipulating them.
This is in contrast to other platforms where they are mapped to a specific
linker option by the compiler. This difference is a result of the greater
variety of ELF linkers and the fact that ELF linkers tend to handle libraries in
a more complicated fashion than on other platforms. This forces us to defer
handling the specifiers to the linker.

In order to achieve a level of source code compatibility with other platforms
we have restricted this feature to work with libraries that meet the following
"reasonable" requirements:

1. There are no competing defined symbols in a given set of libraries, or
   if they exist, the program owner doesn't care which is linked to their
   program.
2. There may be circular dependencies between libraries.

The binary representation is a mergeable string section (SHF_MERGE,
SHF_STRINGS), called .deplibs, with custom type SHT_LLVM_DEPENDENT_LIBRARIES
(0x6fff4c04). The compiler forms this section by concatenating the arguments of
the "comment lib" pragmas and --dependent-library options in the order they are
encountered. Partial (-r, -Ur) links are handled by concatenating .deplibs
sections with the normal mergeable string section rules. As an example, #pragma
comment(lib, "foo") would result in:

.section ".deplibs","MS",@llvm_dependent_libraries,1
         .asciz "foo"

For LTO, equivalent information to the contents of a the .deplibs section can be
retrieved by the LLD for bitcode input files.

LLD processes the dependent library specifiers in the following way:

1. Dependent libraries which are found from the specifiers in .deplibs sections
   of relocatable object files are added when the linker decides to include that
   file (which could itself be in a library) in the link. Dependent libraries
   behave as if they were appended to the command line after all other options. As
   a consequence the set of dependent libraries are searched last to resolve
   symbols.
2. It is an error if a file cannot be found for a given specifier.
3. Any command line options in effect at the end of the command line parsing apply
   to the dependent libraries, e.g. --whole-archive.
4. The linker tries to add a library or relocatable object file from each of the
   strings in a .deplibs section by; first, handling the string as if it was
   specified on the command line; second, by looking for the string in each of the
   library search paths in turn; third, by looking for a lib<string>.a or
   lib<string>.so (depending on the current mode of the linker) in each of the
   library search paths.
5. A new command line option --no-dependent-libraries tells LLD to ignore the
   dependent libraries.

Rationale for the above points:

1. Adding the dependent libraries last makes the process simple to understand
   from a developers perspective. All linkers are able to implement this scheme.
2. Error-ing for libraries that are not found seems like better behavior than
   failing the link during symbol resolution.
3. It seems useful for the user to be able to apply command line options which
   will affect all of the dependent libraries. There is a potential problem of
   surprise for developers, who might not realize that these options would apply
   to these "invisible" input files; however, despite the potential for surprise,
   this is easy for developers to reason about and gives developers the control
   that they may require.
4. This algorithm takes into account all of the different ways that ELF linkers
   find input files. The different search methods are tried by the linker in most
   obvious to least obvious order.
5. I considered adding finer grained control over which dependent libraries were
   ignored (e.g. MSVC has /nodefaultlib:<library>); however, I concluded that this
   is not necessary: if finer control is required developers can fall back to using
   the command line directly.

RFC thread: http://lists.llvm.org/pipermail/llvm-dev/2019-March/131004.html.

Differential Revision: https://reviews.llvm.org/D60274

llvm-svn: 360984
2019-05-17 03:44:15 +00:00
Teresa Johnson
69b4df22e0 [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
2019-05-10 20:08:24 +00:00
Fangrui Song
4ded17c871 [LTO] Migrate typedef to using
using has been used in several places in the file. Migrate the rest for consistency.

llvm-svn: 359776
2019-05-02 10:52:34 +00:00
Steven Wu
feb609a738 [ThinLTO] Adding architecture name into saved object filename
Summary:
For ThinLTOCodegenerator, it has an option to save the object file
outputs into a directory which is essential for debug info. Tools like lldb
and dsymutil will look for these object files for debug info.

On Darwin platform, you can link fat binaries with one single clang
driver invocation like:
 $ clang -arch x86_64 -arch i386 -Wl,-object_path_lto,$TMPDIR ...
Unfornately, the output object files for one architecture is going to
overwrite the previous ones and one architecture slice will end up with
no debug info. One example for this is to turn on ThinLTO for sanitizer
dylibs in compiler-rt project.

To fix the issue, add the name for the architecture into the name of the
output object file.

rdar://problem/35482935

Reviewers: tejohnson, bd1976llvm, dexonsmith, JDevlieghere

Reviewed By: dexonsmith

Subscribers: mehdi_amini, aprantl, inglorion, eraman, hiraditya, jkorous, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60924

llvm-svn: 359508
2019-04-29 21:39:54 +00:00
Florian Hahn
f7a6a1bc36 [LTO] Add plumbing to save stats during LTO on Darwin.
Gold and ld on Linux already support saving stats, but the
infrastructure is missing on Darwin. Unfortunately it seems like the
configuration from lib/LTO/LTO.cpp is not used.

This patch adds a new LTOStatsFile option and adds plumbing in Clang to
use it on Darwin, similar to the way remarks are handled.

Currnetly the handling of LTO flags seems quite spread out, with a bunch
of duplication. But I am not sure if there is an easy way to improve
that?

Reviewers: anemet, tejohnson, thegameg, steven_wu

Reviewed By: steven_wu

Differential Revision: https://reviews.llvm.org/D60516

llvm-svn: 358753
2019-04-19 12:36:41 +00:00
Steven Wu
4fc1c31a27 [ThinLTO] Fix ThinLTOCodegenerator to export llvm.used symbols
Summary:
Reapply r357931 with fixes to ThinLTO testcases and llvm-lto tool.

ThinLTOCodeGenerator currently does not preserve llvm.used symbols and
it can internalize them. In order to pass the necessary information to the
legacy ThinLTOCodeGenerator, the input to the code generator is
rewritten to be based on lto::InputFile.

Now ThinLTO using the legacy LTO API will requires data layout in
Module.

"internalize" thinlto action in llvm-lto is updated to run both
"promote" and "internalize" with the same configuration as
ThinLTOCodeGenerator. The old "promote" + "internalize" option does not
produce the same output as ThinLTOCodeGenerator.

This fixes: PR41236
rdar://problem/49293439

Reviewers: tejohnson, pcc, kromanova, dexonsmith

Reviewed By: tejohnson

Subscribers: ormris, bd1976llvm, mehdi_amini, inglorion, eraman, hiraditya, jkorous, dexonsmith, arphaman, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60421

llvm-svn: 358601
2019-04-17 17:38:09 +00:00
Steven Wu
e757d7f8e8 Revert [ThinLTO] Fix ThinLTOCodegenerator to export llvm.used symbols
This reverts r357931 (git commit 8b70a5c11e08116955a875b9085433f14737bcaf)

llvm-svn: 357932
2019-04-08 18:53:21 +00:00
Steven Wu
9ddbd54259 [ThinLTO] Fix ThinLTOCodegenerator to export llvm.used symbols
Summary:
ThinLTOCodeGenerator currently does not preserve llvm.used symbols and
it can internalize them. In order to pass the necessary information to the
legacy ThinLTOCodeGenerator, the input to the code generator is
rewritten to be based on lto::InputFile.

This fixes: PR41236
rdar://problem/49293439

Reviewers: tejohnson, pcc, dexonsmith

Reviewed By: tejohnson

Subscribers: mehdi_amini, inglorion, eraman, hiraditya, jkorous, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60226

llvm-svn: 357931
2019-04-08 18:24:10 +00:00
Francis Visoiu Mistrih
14e47fc8be Reland "[Remarks] Add -foptimization-record-passes to filter remark emission"
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.

This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`

will only emit the remarks coming from the pass `inline`.

This adds:

* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin

Differential Revision: https://reviews.llvm.org/D59268

Original llvm-svn: 355964

llvm-svn: 355984
2019-03-12 21:22:27 +00:00
Francis Visoiu Mistrih
b72c67b1b1 Revert "[Remarks] Add -foptimization-record-passes to filter remark emission"
This reverts commit 20fff32b7d1f1a1bd417b22aa9f26ededd97a3e5.

llvm-svn: 355976
2019-03-12 20:54:18 +00:00
Francis Visoiu Mistrih
5fb25c63d5 [Remarks] Add -foptimization-record-passes to filter remark emission
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.

This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`

will only emit the remarks coming from the pass `inline`.

This adds:

* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin

Differential Revision: https://reviews.llvm.org/D59268

llvm-svn: 355964
2019-03-12 20:28:50 +00:00
Rong Xu
d2acd4c4e2 Recommit r354930 "[PGO] Context sensitive PGO (part 1)"
Fixed UBSan failures.

llvm-svn: 355005
2019-02-27 17:24:33 +00:00
Vlad Tsyrklevich
3def5ac311 Revert "[PGO] Context sensitive PGO (part 1)"
This reverts commit r354930, it was causing UBSan failures.

llvm-svn: 354953
2019-02-27 03:45:28 +00:00
Rong Xu
a0b71feeed [PGO] Context sensitive PGO (part 1)
Current PGO profile counts are not context sensitive. The branch probabilities
for the inlined functions are kept the same for all call-sites, and they might
be very different from the actual branch probabilities. These suboptimal
profiles can greatly affect some downstream optimizations, in particular for
the machine basic block placement optimization.

In this patch, we propose to have a post-inline PGO instrumentation/use pass,
which we called Context Sensitive PGO (CSPGO). For the users who want the best
possible performance, they can perform a second round of PGO instrument/use on
the top of the regular PGO. They will have two sets of profile counts. The
first pass profile will be manly for inline, indirect-call promotion, and
CGSCC simplification pass optimizations. The second pass profile is for
post-inline optimizations and code-gen optimizations.

A typical usage:
// Regular PGO instrumentation and generate pass1 profile.
> clang -O2 -fprofile-generate source.c -o gen
> ./gen
> llvm-profdata merge default.*profraw -o pass1.profdata
// CSPGO instrumentation.
> clang -O2 -fprofile-use=pass1.profdata -fcs-profile-generate -o gen2
> ./gen2
// Merge two sets of profiles
> llvm-profdata merge default.*profraw pass1.profdata -o profile.profdata
// Use the combined profile. Pass manager will invoke two PGO use passes.
> clang -O2 -fprofile-use=profile.profdata -o use

This change touches many components in the compiler. The reviewed patch
(D54175) will committed in phrases.

Differential Revision: https://reviews.llvm.org/D54175

llvm-svn: 354930
2019-02-26 22:37:46 +00:00
Bob Haarman
33d844b804 [lld-link] preserve @llvm.used symbols in LTO
Summary:
We translate @llvm.used to COFF by generating /include directives
in the .drectve section. However, in LTO links, this happens after
directives have already been processed, so the new directives do
not take effect. This change marks @llvm.used symbols as GCRoots
so that they are preserved as intended.

Fixes PR40733.

Reviewers: rnk, pcc, ruiu

Reviewed By: ruiu

Subscribers: mehdi_amini, steven_wu, dexonsmith, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58255

llvm-svn: 354410
2019-02-20 00:26:01 +00:00
Teresa Johnson
709aaf7b4d [ThinLTO] Detect partially split modules during the thin link
Summary:
The changes to disable LTO unit splitting by default (r350949) and
detect inconsistently split LTO units (r350948) are causing some crashes
when the inconsistency is detected in multiple threads simultaneously.
Fix that by having the code always look for the inconsistently split
LTO units during the thin link, by checking for the presence of type
tests recorded in the summaries.

Modify test added in r350948 to remove single threading required to fix
a bot failure due to this issue (and some debugging options added in the
process of diagnosing it).

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57561

llvm-svn: 354062
2019-02-14 21:22:50 +00:00
Chandler Carruth
ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
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.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Teresa Johnson
52c19ef944 [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
2019-01-11 18:31:57 +00:00
Easwaran Raman
8482e48d19 [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
2018-12-13 19:54:27 +00:00
Teresa Johnson
525ee88977 [ThinLTO] Import local variables from the same module as caller
Summary:
We can sometimes end up with multiple copies of a local variable that
have the same GUID in the index. This happens when there are local
variables with the same name that are in different source files having the
same name/path at compile time (but compiled into different bitcode objects).

In this case make sure we import the copy in the caller's module.
This enables importing both of the variables having the same GUID
(but which will have different promoted names since the module paths,
and therefore the module hashes, will be distinct).

Importing the wrong copy is particularly problematic for read only
variables, since we must import them as a local copy whenever
referenced. Otherwise we get undefs at link time.

Note that the llvm-lto.cpp and ThinLTOCodeGenerator changes are needed
for testing the distributed index case via clang, which will be sent as
a separate clang-side patch shortly. We were previously not doing the
dead code/read only computation before computing imports when testing
distributed index generation (like it was for testing importing and
other ThinLTO mechanisms alone).

Reviewers: evgeny777

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, dang, llvm-commits

Differential Revision: https://reviews.llvm.org/D55047

llvm-svn: 347886
2018-11-29 17:02:42 +00:00
Teresa Johnson
388284330d [ThinLTO] Consolidate cache key computation between new/old LTO APIs
Summary:
The old legacy LTO API had a separate cache key computation, which was
a subset of the cache key computation in the new LTO API (from what I
can tell this is largely just because certain features such as CFI,
dsoLocal, etc are only utilized via the new LTO API). However, having
separate computations is unnecessary (much of the code is duplicated),
and can lead to bugs when adding new optimizations if both cache
computation algorithms aren't updated properly - it's much easier to
maintain if we have a single facility.

This patch refactors the old LTO API code to use the cache key
computation from the new LTO API. To do this, we set up an lto::Config
object and fill in the fields that the old LTO was hashing (the others
will just use the defaults).

There are two notable changes:
- I added a Freestanding flag to the LTO Config. Currently this is only
used by the legacy LTO API. In the patch that added it (D30791) I had
asked about adding it to the new LTO API, but it looks like that was not
addressed. This should probably be discussed as a follow up to this
change, as it is orthogonal.
- The legacy LTO API had some code that was hashing the GUID of all
preserved symbols defined in the module. I looked back at the history of
this (which was added with the original hashing in the legacy LTO API in
D18494), and there is a comment in the review thread that it was added
in preparation for future internalization. We now do the internalization
of course, and that is handled in the new LTO API cache key computation
by hashing the recorded linkage type of all defined globals. Therefore I
didn't try to move over and keep the preserved symbols handling.

Reviewers: steven_wu, pcc

Subscribers: mehdi_amini, inglorion, eraman, dexonsmith, dang, llvm-commits

Differential Revision: https://reviews.llvm.org/D54635

llvm-svn: 347592
2018-11-26 20:40:37 +00:00
Pirama Arumuga Nainar
d61dc6f44b [LTO] Drop non-prevailing definitions only if linkage is not local or appending
Summary:
This fixes PR 37422

In ELF, non-weak symbols can also be non-prevailing.  In this particular
PR, the __llvm_profile_* symbols are non-prevailing but weren't getting
dropped - causing multiply-defined errors with lld.

Also add a test, strong_non_prevailing.ll, to ensure that multiple
copies of a strong symbol are dropped.

To fix the test regressions exposed by this fix,
- do not mark prevailing copies for symbols with 'appending' linkage.
There's no one prevailing copy for such symbols.
- fix the prevailing version in dead-strip-fulllto.ll
- explicitly pass exported symbols to llvm-lto in fumcimport.ll and
funcimport_var.ll

Reviewers: tejohnson, pcc

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith,
dang, srhines, llvm-commits

Differential Revision: https://reviews.llvm.org/D54125

llvm-svn: 346436
2018-11-08 20:10:07 +00:00
Xin Tong
243da175c1 [ThinLTO] Add an option to disable (thin)lto internalization.
Summary:
LTO and ThinLTO optimizes the IR differently.

One source of differences is the amount of internalizations that
can happen.

Add an option to enable/disable internalization so that other
differences can be studied in isolation. e.g. inlining.

There are other things lto and thinlto do differently, I will add
flags to enable/disable them as needed.

Reviewers: tejohnson, pcc, steven_wu

Subscribers: mehdi_amini, inglorion, steven_wu, dexonsmith, dang, llvm-commits

Differential Revision: https://reviews.llvm.org/D53294

llvm-svn: 346140
2018-11-05 15:49:46 +00:00
Richard Smith
4a1cdc1ae5 Add a flag to remap manglings when reading profile data information.
This can be used to preserve profiling information across codebase
changes that have widespread impact on mangled names, but across which
most profiling data should still be usable. For example, when switching
from libstdc++ to libc++, or from the old libstdc++ ABI to the new ABI,
or even from a 32-bit to a 64-bit build.

The user can provide a remapping file specifying parts of mangled names
that should be treated as equivalent (eg, std::__1 should be treated as
equivalent to std::__cxx11), and profile data will be treated as
applying to a particular function if its name is equivalent to the name
of a function in the profile data under the provided equivalences. See
the documentation change for a description of how this is configured.

Remapping is supported for both sample-based profiling and instruction
profiling. We do not support remapping indirect branch target
information, but all other profile data should be remapped
appropriately.

Support is only added for the new pass manager. If someone wants to also
add support for this for the old pass manager, doing so should be
straightforward.

This is the LLVM side of Clang r344199.

Reviewers: davidxl, tejohnson, dlj, erik.pilkington

Subscribers: mehdi_amini, steven_wu, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D51249

llvm-svn: 344200
2018-10-10 23:13:47 +00:00
James Henderson
cd11b8eeed Reland r342233: [ThinLTO] Allow setting of maximum cache size with 64-bit number
The original was reverted due to an apparent build-bot test failure,
but it looks like this is just a flaky test.

Also added a C-interface function for large values, and updated
llvm-lto's --thinlto-cache-max-size-bytes switch to take a type larger
than int.

The maximum cache size in terms of bytes is a 64-bit number. However,
the methods to set it only took unsigned previously, which meant that
the maximum cache size could not be specified above 4GB. That's quite
small compared to the output of some projects, so it makes sense to
provide the ability to set larger values in that field.

We also needed a C-interface function that provides a greater range
than the existing thinlto_codegen_set_cache_size_bytes, which also only
takes an unsigned, so this change also adds
hinlto_codegen_set_cache_size_megabytes.

Reviewed by: mehdi_amini, tejohnson, steven_wu

Differential Revision: https://reviews.llvm.org/D52023

llvm-svn: 342366
2018-09-17 10:21:26 +00:00
James Henderson
10c88305f4 Revert r342233.
This caused LLD test failures, which I've been unable to reproduce.

Reverting to allow for further investigation next week.

llvm-svn: 342244
2018-09-14 16:48:47 +00:00
James Henderson
71bb756ca9 [ThinLTO]Allow setting of maximum cache size with 64-bit number
Also added a C-interface function for large values, and updated
llvm-lto's --thinlto-cache-max-size-bytes switch to take a type larger
than int.

The maximum cache size in terms of bytes is a 64-bit number. However,
the methods to set it only took unsigned previously, which meant that
the maximum cache size could not be specified above 4GB. That's quite
small compared to the output of some projects, so it makes sense to
provide the ability to set larger values in that field.

We also needed a C-interface function that provides a greater range
than the existing thinlto_codegen_set_cache_size_bytes, which also only
takes an unsigned, so this change also adds
hinlto_codegen_set_cache_size_megabytes.

Reviewed by: mehdi_amini, tejohnson, steven_wu

Differential Revision: https://reviews.llvm.org/D52023

llvm-svn: 342233
2018-09-14 12:51:19 +00:00
Steven Wu
60afa177aa [ThinLTO] Fix memory corruption in ThinLTOCodeGenerator when CodeGenOnly was specified
Summary:
Issue occurs when doing ThinLTO with CodeGenOnly flag.
TMBuilder.TheTriple is assigned to by multiple threads in an unsafe way resulting in double-free of std::string memory.

Pseudocode:
if (CodeGenOnly) {
  // Perform only parallel codegen and return.
  ThreadPool Pool;
  int count = 0;
  for (auto &ModuleBuffer : Modules) {
    Pool.async([&](int count) {
    ...
      /// Now call OutputBuffer = codegen(*TheModule);
      /// Which turns into initTMBuilder(moduleTMBuilder, Triple(TheModule.getTargetTriple()));
      /// Which turns into

      TMBuilder.TheTriple = std::move(TheTriple);   // std::string = "....."
      /// So, basically std::string assignment to same string on multiple threads = memory corruption

  }

  return;
}

Patch by Alex Borcan

Reviewers: llvm-commits, steven_wu

Reviewed By: steven_wu

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D51651

llvm-svn: 341422
2018-09-04 22:54:17 +00:00
Peter Collingbourne
b3516134ef IRGen: Write .dwo files when -split-dwarf-file is used together with -fthinlto-index.
Differential Revision: https://reviews.llvm.org/D47597

llvm-svn: 333677
2018-05-31 18:25:59 +00:00
Peter Collingbourne
13afbf5f9e LTO: Replace split dwarf implementation that uses objcopy with one that uses direct emission.
Part of PR37466.

Differential Revision: https://reviews.llvm.org/D47091

llvm-svn: 332884
2018-05-21 20:26:49 +00:00
Florian Hahn
dd48f29ba7 [LTO] Add stats-file option to LTO/Config.h.
This patch adds a StatsFile option to LTO/Config.h and updates both
LLVMGold and llvm-lto2 to set it.

Reviewers: MatzeB, tejohnson, espindola

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D45531

llvm-svn: 330411
2018-04-20 10:18:36 +00:00
Yunlian Jiang
dfd7baa5a5 Enable debug fission for thinLTO linked via gold-plugin
Summary: This enables debug fission on implicit ThinLTO when linked with gold. It will put the .dwo files in a directory specified by user. 

Reviewers: tejohnson, pcc, dblaikie

Reviewed By: pcc

Subscribers: JDevlieghere, mehdi_amini, inglorion

Differential Revision: https://reviews.llvm.org/D44792

llvm-svn: 329988
2018-04-13 05:03:28 +00:00
David Blaikie
dcf19ce471 Sink Analysis/ObjectUtil(canBeOmittedFromSymbolTable) into IR so it can be legitimately be used by Object/IRSymtab
llvm-svn: 328135
2018-03-21 19:23:45 +00:00
Bob Haarman
6f58d8aefa Revert "[LTO] Support filtering by hotness threshold"
This reverts commit 1f3bd185c53beb6aa68446974b7e80837abd6ef0 (r326107)
because it fails
ThinLTO/X86/diagnostic-handler-remarks-with-hotness.ll.

llvm-svn: 326975
2018-03-08 01:13:10 +00:00
Ekaterina Romanova
26e5ff8165 [ThinLTO] Added a couple of C LTO API interfaces to control the cache policy.
- thinlto_codegen_set_cache_size_bytes to control the absolute size of cache directory. 
- thinlto_codegen_set_cache_size_files the size and amount of files in cache directory. 
These functions have been supported in C++ LTO API for a long time, but were absent in C LTO API.

Differential Revision: https://reviews.llvm.org/D42446

llvm-svn: 326537
2018-03-02 03:51:27 +00:00
Adam Nemet
dd0f9242a1 [LTO] Support filtering by hotness threshold
This wires up -pass-remarks-hotness-threshold to LTO and ThinLTO.

Next is to change the clang driver to pass this
with -fdiagnostics-hotness-threshold.

Differential Revision: https://reviews.llvm.org/D41465

llvm-svn: 326107
2018-02-26 18:37:45 +00:00
Vitaly Buka
b49050d555 [ThinLTO] Always create linked objects file for --thinlto-index-only=
Summary:
ThinLTO indexing may decide to skip all objects. If we don't write something to
the list build system may consider this as failure or linker can reuse a file
from the previews build.

Reviewers: pcc, tejohnson

Subscribers: mehdi_amini, inglorion, eraman, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D43415

llvm-svn: 325819
2018-02-22 19:06:15 +00:00