10336 Commits

Author SHA1 Message Date
Francis Visoiu Mistrih
aad252295b Reland "[Remarks] Add a new Remark / RemarkParser abstraction"
This adds a Remark class that allows us to share code when working with
remarks.

The C API has been updated to reflect this. Instead of the parser
generating C structs, it's now using a C++ object that is used through
opaque pointers in C. This gives us much more flexibility on what
changes we can make to the internal state of the object and interacts
much better with scenarios where the library is used through dlopen.

* C API updates:
  * move from C structs to opaque pointers and functions
  * the remark type is now an enum instead of a string
* unit tests updates:
  * use mostly the C++ API
  * keep one test for the C API
  * rename to YAMLRemarksParsingTest
* a typo was fixed: AnalysisFPCompute -> AnalysisFPCommute.
* a new error message was added: "expected a remark tag."
* llvm-opt-report has been updated to use the C++ parser instead of the
C API

Differential Revision: https://reviews.llvm.org/D59049

Original llvm-svn: 356491

llvm-svn: 356519
2019-03-19 21:11:07 +00:00
Francis Visoiu Mistrih
a58b553f92 Revert "[Remarks] Add a new Remark / RemarkParser abstraction"
This reverts commit 51dc6a8c84cd6a58562e320e1828a0158dbbf750.

Breaks
http://lab.llvm.org:8011/builders/clang-cmake-x86_64-sde-avx512-linux/builds/20034/steps/build%20stage%201/logs/stdio.

llvm-svn: 356492
2019-03-19 18:21:43 +00:00
Francis Visoiu Mistrih
de75d7efaf [Remarks] Add a new Remark / RemarkParser abstraction
This adds a Remark class that allows us to share code when working with
remarks.

The C API has been updated to reflect this. Instead of the parser
generating C structs, it's now using a C++ object that is used through
opaque pointers in C. This gives us much more flexibility on what
changes we can make to the internal state of the object and interacts
much better with scenarios where the library is used through dlopen.

* C API updates:
  * move from C structs to opaque pointers and functions
  * the remark type is now an enum instead of a string
* unit tests updates:
  * use mostly the C++ API
  * keep one test for the C API
  * rename to YAMLRemarksParsingTest
* a typo was fixed: AnalysisFPCompute -> AnalysisFPCommute.
* a new error message was added: "expected a remark tag."
* llvm-opt-report has been updated to use the C++ parser instead of the
C API

Differential Revision: https://reviews.llvm.org/D59049

llvm-svn: 356491
2019-03-19 18:09:51 +00:00
Jordan Rupprecht
4229c66a80 [llvm-ar] Support N [count] modifier
Summary:
GNU ar supports the 'N' count modifier for the extract (x) and delete (d) operations. When an archive contains multiple members with the same name, this can be used to extract (or delete) them individually. For example:

```
$ llvm-ar t archive.a
foo
foo
$ llvm-ar x archive.a
-> Writes foo twice, overwriting it the second time :( :(
$ llvm-ar xN 1 archive.a foo && mv foo foo.1
$ llvm-ar xN 2 archive.a foo && mv foo foo.2
-> Write foo twice, renaming it in between invocations to preserve all versions
```

Reviewers: ruiu, MaskRay

Reviewed By: ruiu, MaskRay

Subscribers: jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59503

llvm-svn: 356466
2019-03-19 16:09:54 +00:00
Serge Guelton
ff8e1cddfe Use response file when generating LLVM-C.dll
As discovered in D56774 the command line gets to long, so use a response file
to give the script the libs. This change has been tested and is confirmed
working for me.

Commited on behalf of Jakob Bornecrantz.
Differential Revision: https://reviews.llvm.org/D56781

llvm-svn: 356443
2019-03-19 09:14:09 +00:00
Jake Ehrlich
83efed9fe8 [llvm-objcopy] Make .build-id linking atomic
This change makes linking into .build-id atomic and safe to use.
Some users under particular workflows are reporting that this races
more than half the time under particular conditions.

llvm-svn: 356404
2019-03-18 20:35:18 +00:00
George Rimar
85af6d1c85 [llvm-objcopy] - Calculate the string table section sizes correctly.
This fixes the https://bugs.llvm.org/show_bug.cgi?id=40980.

Previously if string optimization occurred as a result of
StringTableBuilder's finalize() method, the size wasn't updated.

This hopefully also makes the interaction between sections during finalization
processes a bit more clear.

Differential revision: https://reviews.llvm.org/D59488

llvm-svn: 356371
2019-03-18 14:27:41 +00:00
Roman Lebedev
5d84c488b2 [llvm-exegesis] Separate tool options into three categories.
Results in much nicer -help output:
```
$ ./bin/llvm-exegesis -help
USAGE: llvm-exegesis [options]

OPTIONS:

Color Options:

  -color                                         - Use colors in output (default=autodetect)

General options:

  -enable-cse-in-irtranslator                    - Should enable CSE in irtranslator
  -enable-cse-in-legalizer                       - Should enable CSE in Legalizer

Generic Options:

  -help                                          - Display available options (-help-hidden for more)
  -help-list                                     - Display list of available options (-help-list-hidden for more)
  -version                                       - Display the version of this program

llvm-exegesis analysis options:

  -analysis-clustering-epsilon=<number>          - dbscan epsilon for benchmark point clustering
  -analysis-clusters-output-file=<string>        -
  -analysis-display-unstable-clusters            - if there is more than one benchmark for an opcode, said benchmarks may end up not being clustered into the same cluster if the measured performance characteristics are different. by default all such opcodes are filtered out. this flag will instead show only such unstable opcodes
  -analysis-inconsistencies-output-file=<string> -
  -analysis-inconsistency-epsilon=<number>       - epsilon for detection of when the cluster is different from the LLVM schedule profile values
  -analysis-numpoints=<uint>                     - minimum number of points in an analysis cluster

llvm-exegesis benchmark options:

  -ignore-invalid-sched-class                    - ignore instructions that do not define a sched class
  -mode=<value>                                  - the mode to run
    =latency                                     -   Instruction Latency
    =inverse_throughput                          -   Instruction Inverse Throughput
    =uops                                        -   Uop Decomposition
    =analysis                                    -   Analysis
  -num-repetitions=<uint>                        - number of time to repeat the asm snippet
  -opcode-index=<int>                            - opcode to measure, by index
  -opcode-name=<string>                          - comma-separated list of opcodes to measure, by name
  -snippets-file=<string>                        - code snippets to measure

llvm-exegesis options:

  -benchmarks-file=<string>                      - File to read (analysis mode) or write (latency/uops/inverse_throughput modes) benchmark results. “-” uses stdin/stdout.
  -mcpu=<string>                                 - cpu name to use for pfm counters, leave empty to autodetect
```

llvm-svn: 356364
2019-03-18 11:32:37 +00:00
Fangrui Song
109967fa40 [llvm-profdata] Deleted unused Cutoffs added by D16005
llvm-svn: 356248
2019-03-15 10:43:51 +00:00
James Henderson
cccf1bdc3a [yaml2obj]Allow explicit setting of p_filesz, p_memsz, and p_offset
yaml2obj currently derives the p_filesz, p_memsz, and p_offset values of
program headers from their sections. This makes writing tests for
certain formats more complex, and sometimes impossible. This patch
allows setting these fields explicitly, overriding the default value,
when relevant.

Reviewed by: jakehehrlich, Higuoxing

Differential Revision: https://reviews.llvm.org/D59372

llvm-svn: 356247
2019-03-15 10:35:27 +00:00
Fangrui Song
0e49cca591 [llvm-readobj] Delete unused variable. NFC
llvm-svn: 356246
2019-03-15 10:34:57 +00:00
Fangrui Song
9abcfb073d [llvm-objcopy] Delete unused parameter from replaceDebugSections. NFC
llvm-svn: 356245
2019-03-15 10:27:28 +00:00
Fangrui Song
afd6b2d8c3 [llvm-objcopy] Don't use {}; NFC
llvm-svn: 356244
2019-03-15 10:20:51 +00:00
Jordan Rupprecht
48ffd0d44c [llvm-strip] Hook up (unimplemented) --only-keep-debug
For ELF, we accept but ignore --only-keep-debug. Do the same for llvm-strip.

COFF does implement this, so update the test that it is supported.

llvm-svn: 356207
2019-03-14 21:51:42 +00:00
Max Moroz
31cf7668c7 Speeding up llvm-cov export with multithreaded renderFiles implementation.
Summary:
CoverageExporterJson::renderFiles accounts for most of the execution time given a large profdata file with multiple binaries.

Proposed solution is to generate JSON for each file in parallel and sort at the end to preserve deterministic output. Also added flags to skip generating parts of the output to trim the output size.

Patch by Sajjad Mirza (@sajjadm).

Reviewers: Dor1s, vsk

Reviewed By: Dor1s, vsk

Subscribers: liaoyuke, mgrang, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59277

llvm-svn: 356178
2019-03-14 17:49:27 +00:00
James Henderson
f563d45752 [llvm-objcopy]Don't implicitly strip sections in segments
This patch changes llvm-objcopy's behaviour to not strip sections that
are in segments, if they otherwise would be due to a stripping operation
(--strip-all, --strip-sections, --strip-non-alloc). This preserves the
segment contents. It does not change the behaviour of --strip-all-gnu
(although we could choose to do so), because GNU objcopy's behaviour in
this case seems to be to strip the section, nor does it prevent removing
of sections in segments with --remove-section (if a user REALLY wants to
remove a section, we should probably let them, although I could be
persuaded that warning might be appropriate). Tests have been added to
show this latter behaviour.

This fixes https://bugs.llvm.org/show_bug.cgi?id=41006.

Reviewed by: grimar, rupprecht, jakehehrlich

Differential Revision: https://reviews.llvm.org/D59293

This is a reland of r356129, attempting to fix greendragon failures
due to a suspected compatibility issue with od on the greendragon bots
versus other versions.

llvm-svn: 356136
2019-03-14 11:47:41 +00:00
James Henderson
88e40ab1b8 Revert r356129 due to greendragon bot failures
llvm-svn: 356133
2019-03-14 11:23:04 +00:00
James Henderson
1bd484c2b8 [llvm-objcopy]Don't implicitly strip sections in segments
This patch changes llvm-objcopy's behaviour to not strip sections that
are in segments, if they otherwise would be due to a stripping operation
(--strip-all, --strip-sections, --strip-non-alloc). This preserves the
segment contents. It does not change the behaviour of --strip-all-gnu
(although we could choose to do so), because GNU objcopy's behaviour in
this case seems to be to strip the section, nor does it prevent removing
of sections in segments with --remove-section (if a user REALLY wants to
remove a section, we should probably let them, although I could be
persuaded that warning might be appropriate). Tests have been added to
show this latter behaviour.

This fixes https://bugs.llvm.org/show_bug.cgi?id=41006.

Reviewed by: grimar, rupprecht, jakehehrlich

Differential Revision: https://reviews.llvm.org/D59293

llvm-svn: 356129
2019-03-14 10:20:27 +00:00
Jordan Rupprecht
4047825f64 [llvm-objcopy][NFC] Remove unnecessary llvm-objcopy.h #includes
llvm-svn: 356109
2019-03-13 23:40:16 +00:00
Jordan Rupprecht
bd637ddd64 [llvm-objcopy] Cleanup errors from CopyConfig and remove llvm-objcopy.h dependency
error() was previously cleaned up from CopyConfig, but new uses were introduced.

This also tweaks the error message for --add-symbol to report all invalid flags.

llvm-svn: 356105
2019-03-13 22:26:01 +00:00
Tim Renouf
0740b7d5b8 [AMDGPU] Switched HSA metadata to use MsgPackDocument
Summary:
MsgPackDocument is the lighter-weight replacement for MsgPackTypes. This
commit switches AMDGPU HSA metadata processing to use MsgPackDocument
instead of MsgPackTypes.

Differential Revision: https://reviews.llvm.org/D57024

Change-Id: I0751668013abe8c87db01db1170831a76079b3a6
llvm-svn: 356081
2019-03-13 18:55:50 +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
James Henderson
9af6a3c5cb [yaml2obj]Allow explicit symbol indexes in relocations and emit error for bad names
Prior to this change, the "Symbol" field of a relocation would always be
assumed to be a symbol name, and if no such symbol existed, the
relocation would reference index 0. This confused me when I tried to use
a literal symbol index in the field: since "0x1" was not a known symbol
name, the symbol index was set as 0. This change falls back to treating
unknown symbol names as integers, and emits an error if the name is not
found and the string is not an integer.

Note that the Symbol field is optional, so if a relocation doesn't
reference a symbol, it shouldn't be specified. The new error required a
number of test updates.

Reviewed by: grimar, ruiu
Differential Revision: https://reviews.llvm.org/D58510

llvm-svn: 355938
2019-03-12 17:00:25 +00:00
Xing GUO
737a42660e [llvm-readobj] Print symbol version when dumping relocations (PR31564)
Summary: This helps resolve https://bugs.llvm.org/show_bug.cgi?id=31564

Reviewers: jhenderson, grimar

Reviewed By: jhenderson

Subscribers: rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59175

llvm-svn: 355922
2019-03-12 14:30:13 +00:00
Eugene Leviant
27a13eb691 [llvm-objcopy] Remove unneeded checks. NFC
Differential revision: https://reviews.llvm.org/D59081

llvm-svn: 355914
2019-03-12 12:41:06 +00:00
Peter Collingbourne
ab72ac7186 llvm-objcopy: Remove unused field. NFCI.
Differential Revision: https://reviews.llvm.org/D59126

llvm-svn: 355892
2019-03-12 02:17:01 +00:00
Nathan Lanza
0368dcdd6e Add Swift enumerator value for CodeView::SourceLanguage
Summary:
Swift now generates PDBs for debugging on Windows. llvm and lldb
need a language enumerator value too properly handle the output
emitted by swiftc.

Subscribers: jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59231

llvm-svn: 355882
2019-03-11 23:27:59 +00:00
George Rimar
757b91db38 [yaml2obj] - Simplify. NFC.
llvm-svn: 355832
2019-03-11 16:10:02 +00:00
George Rimar
3e5b9fe4cd [llvm-objcopy] - Fix --compress-debug-sections when there are relocations.
When --compress-debug-sections is given,
llvm-objcopy removes the uncompressed sections and adds compressed to the section list.
This makes all the pointers to old sections to be outdated.

Currently, code already has logic for replacing the target sections of the relocation
sections. But we also have to update the relocations by themselves.

This fixes https://bugs.llvm.org/show_bug.cgi?id=40885.

Differential revision: https://reviews.llvm.org/D58960

llvm-svn: 355821
2019-03-11 11:01:24 +00:00
Sunil Srivastava
b609f580a3 Improve "llvm-nm -f sysv" output for Elf files
Specifically, compute and Print Type and Section columns.

This is a re-commit of rL354833, after fixing the Asan problem found a a buildbot.

Differential Revision: https://reviews.llvm.org/D59060

llvm-svn: 355742
2019-03-08 22:00:50 +00:00
James Henderson
502ebba706 [llvm-readelf]Don't lose negative-ness of negative addends for no symbol relocations
llvm-readelf prints relocation addends as:

  <symbol value>[+-]<absolute addend>

where [+-] is determined from whether addend is less than zero or not.
However, it does not print the +/- if there is no symbol, which meant
that negative addends became their positive value with no indication
that this had happened. This patch stops the absolute conversion when
addends are negative and there is no associated symbol.

Reviewed by: Higuoxing, mattd, MaskRay

Differential Revision: https://reviews.llvm.org/D59095

llvm-svn: 355696
2019-03-08 13:22:05 +00:00
Matt Davis
28382105e7 [llvm-mca] Emit a message when no bottlenecks are identified.
Summary:
Since bottleneck hints are enabled via user request, it can be
confusing if no bottleneck information is presented.  Such is the
case when no bottlenecks are identified.  This patch emits a message
in that case.

Reviewers: andreadb

Reviewed By: andreadb

Subscribers: tschuett, gbedwell, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59098

llvm-svn: 355628
2019-03-07 19:34:44 +00:00
Xing GUO
ef6399f2ef [llvm-readobj] Dump DT_USED value as string like GNU readelf does
Reviewers: jhenderson

Reviewed By: jhenderson

Subscribers: rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59089

llvm-svn: 355600
2019-03-07 14:53:10 +00:00
George Rimar
bd3c267f5b [yaml2obj] - Allow producing ELFDATANONE ELFs
I need this to remove a binary from LLD test suite.
The patch also simplifies the code a bit.

Differential revision: https://reviews.llvm.org/D59082

llvm-svn: 355591
2019-03-07 12:09:19 +00:00
Francis Visoiu Mistrih
db7c2e63ef Reland "[Remarks] Refactor remark diagnostic emission in a RemarkStreamer"
This allows us to store more info about where we're emitting the remarks
without cluttering LLVMContext. This is needed for future support for
the remark section.

Differential Revision: https://reviews.llvm.org/D58996

Original llvm-svn: 355507

llvm-svn: 355514
2019-03-06 15:20:13 +00:00
Francis Visoiu Mistrih
ab95f38139 Revert "[Remarks] Refactor remark diagnostic emission in a RemarkStreamer"
This reverts commit 2e8c4997a2089f8228c843fd81b148d903472e02.

Breaks bots.

llvm-svn: 355511
2019-03-06 14:52:37 +00:00
Francis Visoiu Mistrih
45571530a1 [Remarks] Refactor remark diagnostic emission in a RemarkStreamer
This allows us to store more info about where we're emitting the remarks
without cluttering LLVMContext. This is needed for future support for
the remark section.

Differential Revision: https://reviews.llvm.org/D58996

llvm-svn: 355507
2019-03-06 14:32:08 +00:00
George Rimar
4f51fe0c01 [llvm-objcopy] - Remove dead code. NFCI.
DecompressedSection can only be created if --decompress-debug-sections is specified.
https://github.com/llvm-mirror/llvm/blob/master/tools/llvm-objcopy/ELF/ELFObjcopy.cpp#L492

If it is specified when !zlib::isAvailable(), we error out early when parsing the options:
https://github.com/llvm-mirror/llvm/blob/master/tools/llvm-objcopy/CopyConfig.cpp#L657

What means the code I am removing in this patch is dead.

Differential revision: https://reviews.llvm.org/D59017

llvm-svn: 355505
2019-03-06 14:12:18 +00:00
George Rimar
edd70802af [llvm-objcopy] - Remove an excessive zlib::isAvailable() check and dead code.
There are 2 places where llvm-objcopy creates CompressedSection:

For --compress-debug-sections. It might create the compressed section from
regular here:
https://github.com/llvm-mirror/llvm/blob/master/tools/llvm-objcopy/ELF/ELFObjcopy.cpp#L486

All initially compressed sections are created as CompressedSection during reading the sections
from an object:
https://github.com/llvm-mirror/llvm/blob/master/tools/llvm-objcopy/ELF/Object.cpp#L1118
Those have DebugCompressionType::None type and a different constructor.

Case 1 has the following code in its constructor:

if (!zlib::isAvailable()) {
  CompressionType = DebugCompressionType::None;
  return;
}
(https://github.com/llvm-mirror/llvm/blob/master/tools/llvm-objcopy/ELF/Object.cpp#L267)

We can never reach that code with because would report an error much earlier:
https://github.com/llvm-mirror/llvm/blob/master/tools/llvm-objcopy/CopyConfig.cpp#L480

So the code I am removing is dead. Landing this will address the issue mentioned in https://bugs.llvm.org/show_bug.cgi?id=40886.

Differential revision: https://reviews.llvm.org/D59019

llvm-svn: 355503
2019-03-06 14:08:27 +00:00
George Rimar
09f6aceae8 [llvm-objcopy] - Fix incorrect CompressedSection creation.
We should create CompressedSection only if the section has SHF_COMPRESSED flag
or it's name starts from '.zdebug'.
Currently, we create it if section's data starts from ZLIB signature.

Differential revision: https://reviews.llvm.org/D59018

llvm-svn: 355501
2019-03-06 14:01:54 +00:00
Florian Hahn
eafd27fedf [opt] Report if the provided architecture is invalid.
Partly addresses PR15026.

There are a few tests that passed in invalid architectures, which are fixed in: rL355349 and D58931

Reviewers: echristo, efriedma, rengolin, atrick

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D58933

llvm-svn: 355455
2019-03-05 23:10:28 +00:00
Francis Visoiu Mistrih
7f77ac0406 [OptRemarks] Make OptRemarks more generic: rename OptRemarks to Remarks
Getting rid of the name "optimization remarks" for anything that
involves handling remarks on the client side.

It's safer to do this now, before we get stuck with that name in all the
APIs and public interfaces we decide to export to users in the future.

This renames llvm/tools/opt-remarks to llvm/tools/remarks-shlib, and now
generates `libRemarks.dylib` instead of `libOptRemarks.dylib`.

Differential Revision: https://reviews.llvm.org/D58535

llvm-svn: 355439
2019-03-05 20:45:17 +00:00
George Rimar
e24ba5947b [llvm-objcopy] - Simplify isCompressable and fix the issue relative.
When --compress-debug-sections is given, llvm-objcopy do not compress
sections that have "ZLIB" header in data. Normally this signature is used
in zlib-gnu compression format. But if zlib-gnu used then the name of the compressed
section should start from .z* (e.g .zdebug_info). If it does not, then it is not
a zlib-gnu format and section should be treated as a normal uncompressed section.

Differential revision: https://reviews.llvm.org/D58908

llvm-svn: 355399
2019-03-05 13:07:43 +00:00
George Rimar
d6ec2efde8 [llvm-objcopy] - Report "no zlib available" error properly when --compress-debug-sections is used.
If zlib is not available, and --compress-debug-sections is passed, 
we want to report an error. Currently, it is only reported for
--compress_debug_sections= form of the option.

Fixes the https://bugs.llvm.org/show_bug.cgi?id=40886.

I do not think there is a way to write a test for this.

Differential revision: https://reviews.llvm.org/D58909

llvm-svn: 355391
2019-03-05 11:32:14 +00:00
Evgeniy Stepanov
135b61b60c Fix wrong enum value in switch.
llvm-svn: 355338
2019-03-04 21:00:28 +00:00
Rong Xu
888aa59db9 [PGO] Context sensitive PGO (part 3)
Part 3 of CSPGO changes (mostly related to PassMananger).

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

llvm-svn: 355330
2019-03-04 20:21:27 +00:00
Andrea Di Biagio
e84fbe16c1 [MCA] Correctly initialize struct SummaryView::BackPressureInfo.
This should appease the buildbots.

llvm-svn: 355309
2019-03-04 12:23:05 +00:00
Andrea Di Biagio
c5a150eca8 [MCA] Highlight kernel bottlenecks in the summary view.
This patch adds a new flag named -bottleneck-analysis to print out information
about throughput bottlenecks.

MCA knows how to identify and classify dynamic dispatch stalls. However, it
doesn't know how to analyze and highlight kernel bottlenecks.  The goal of this
patch is to teach MCA how to correlate increases in backend pressure to backend
stalls (and therefore, the loss of throughput).

From a Scheduler point of view, backend pressure is a function of the scheduler
buffer usage (i.e. how the number of uOps in the scheduler buffers changes over
time). Backend pressure increases (or decreases) when there is a mismatch
between the number of opcodes dispatched, and the number of opcodes issued in
the same cycle.  Since buffer resources are limited, continuous increases in
backend pressure would eventually leads to dispatch stalls. So, there is a
strong correlation between dispatch stalls, and how backpressure changed over
time.

This patch teaches how to identify situations where backend pressure increases
due to:
 - unavailable pipeline resources.
 - data dependencies.

Data dependencies may delay execution of instructions and therefore increase the
time that uOps have to spend in the scheduler buffers. That often translates to
an increase in backend pressure which may eventually lead to a bottleneck.
Contention on pipeline resources may also delay execution of instructions, and
lead to a temporary increase in backend pressure.

Internally, the Scheduler classifies instructions based on whether register /
memory operands are available or not.

An instruction is marked as "ready to execute" only if data dependencies are
fully resolved.
Every cycle, the Scheduler attempts to execute all instructions that are ready
to execute. If an instruction cannot execute because of unavailable pipeline
resources, then the Scheduler internally updates a BusyResourceUnits mask with
the ID of each unavailable resource.

ExecuteStage is responsible for tracking changes in backend pressure. If backend
pressure increases during a cycle because of contention on pipeline resources,
then ExecuteStage sends a "backend pressure" event to the listeners.
That event would contain information about instructions delayed by resource
pressure, as well as the BusyResourceUnits mask.

Note that ExecuteStage also knows how to identify situations where backpressure
increased because of delays introduced by data dependencies.

The SummaryView observes "backend pressure" events and prints out a "bottleneck
report".

Example of bottleneck report:

```
Cycles with backend pressure increase [ 99.89% ]
Throughput Bottlenecks:
  Resource Pressure       [ 0.00% ]
  Data Dependencies:      [ 99.89% ]
   - Register Dependencies [ 0.00% ]
   - Memory Dependencies   [ 99.89% ]
```

A bottleneck report is printed out only if increases in backend pressure
eventually caused backend stalls.

About the time complexity:

Time complexity is linear in the number of instructions in the
Scheduler::PendingSet.

The average slowdown tends to be in the range of ~5-6%.
For memory intensive kernels, the slowdown can be significant if flag
-noalias=false is specified. In the worst case scenario I have observed a
slowdown of ~30% when flag -noalias=false was specified.

We can definitely recover part of that slowdown if we optimize class LSUnit (by
doing extra bookkeeping to speedup queries). For now, this new analysis is
disabled by default, and it can be enabled via flag -bottleneck-analysis. Users
of MCA as a library can enable the generation of pressure events through the
constructor of ExecuteStage.

This patch partially addresses https://bugs.llvm.org/show_bug.cgi?id=37494

Differential Revision: https://reviews.llvm.org/D58728

llvm-svn: 355308
2019-03-04 11:52:34 +00:00