Commit Graph

714 Commits

Author SHA1 Message Date
James Henderson 9485b265e8 [binutils] Add response file option to help and docs
Many LLVM-based tools already support response files (i.e. files
containing a list of options, specified with '@'). This change simply
updates the documentation and help text for some of these tools to
include it. I haven't attempted to fix all tools, just a selection that
I am interested in.

I've taken the opportunity to add some tests for --help behaviour, where
they were missing. We could expand these tests, but I don't think that's
within scope of this patch.

This fixes https://bugs.llvm.org/show_bug.cgi?id=42233 and
https://bugs.llvm.org/show_bug.cgi?id=42236.

Reviewed by: grimar, MaskRay, jkorous

Differential Revision: https://reviews.llvm.org/D63597

llvm-svn: 364036
2019-06-21 11:49:20 +00:00
James Henderson a8ed354b64 [docs][llvm-objdump] Improve llvm-objdump documentation
The llvm-objdump document was missing many options, and there were also
some style issues with it. This patches fixes all but the first issue
listed in https://bugs.llvm.org/show_bug.cgi?id=42249 by:

    1. Adding missing options and commands.
    2. Standardising on double dashes for long-options throughout.
    3. Moving Mach-O specific options to a separate section.
    4. Removing options that don't exist or aren't relevant to
       llvm-objdump.

Reviewed by: MaskRay, mtrent, alexshap

Differential Revision: https://reviews.llvm.org/D63606

llvm-svn: 364019
2019-06-21 10:12:53 +00:00
Thomas Preud'homme a2ef1ba32f [FileCheck] Stop qualifying expressions as numeric
Summary:
Stop referring to "numeric expression", using simply the term
"expression" instead. Likewise for numeric operation since operations
are only used in numeric expressions.

Reviewers: jhenderson, jdenny, probinson, arichardson

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63500

llvm-svn: 363901
2019-06-19 23:47:24 +00:00
Andrea Di Biagio 792510f869 [llvm-mca][docs] clarify how the quality of the perf report is affected by the quality of the scheduling models.
Differential Revision: https://reviews.llvm.org/D63556

llvm-svn: 363830
2019-06-19 16:10:58 +00:00
James Henderson 891cdaab7a [docs][llvm-dwarfdump] Make the --show-parents and --show-children help text and docs more consistent and correct
The docs and help text for --show-parents and --show-children were a bit
inconsistent. The help text claimed they had an effect when "=<offset>"
was used, whereas the doc said it had an effect when "--find" or
"--name" were used. This change changes the doc to mention "=<offset>"
and removes this reference from the help text, to avoid having a very
long description in the help text (it still says "when selectively
printing entries").

Reviewed by: JDevlieghere, aprantl

Differential Revision: https://reviews.llvm.org/D63275

llvm-svn: 363380
2019-06-14 13:00:09 +00:00
Vedant Kumar 901d04fc6d [Coverage] Load code coverage data from archives
Support loading code coverage data from regular archives, thin archives,
and from MachO universal binaries which contain archives.

Testing: check-llvm, check-profile (with {A,UB}San enabled)

rdar://51538999

Differential Revision: https://reviews.llvm.org/D63232

llvm-svn: 363325
2019-06-13 20:48:57 +00:00
James Henderson e6820dac99 [docs][llvm-symbolizer] Fix formatting issue with --functions
Reviewed by: rupprecht

Differential Revision: https://reviews.llvm.org/D63195

llvm-svn: 363266
2019-06-13 13:58:44 +00:00
James Henderson 86b510aa58 [docs][llvm-dwarfdump] Add missing options and behaviour to documentation
This fixes https://bugs.llvm.org/show_bug.cgi?id=42185.

llvm-dwarfdump's documentation was missing a number of options and other
behaviours. This change tries to fix up the documentation by adding
these missing items.

Reviewed by: JDevlieghere

Differential Revision: https://reviews.llvm.org/D63217

llvm-svn: 363264
2019-06-13 13:53:16 +00:00
Shoaib Meenai 8f4973f57b [llvm-lipo] Update llvm-lipo docs for -archs flag
The information for -archs flag is added to llvm-lipo.rst.

Patch by Anusha Basana <anusha.basana@gmail.com>

Differential Revision: https://reviews.llvm.org/D63100

llvm-svn: 363182
2019-06-12 17:37:01 +00:00
James Henderson 31908669c6 [docs][llvm-symbolizer] Fix typo and grammar error
llvm-svn: 363145
2019-06-12 11:41:43 +00:00
James Henderson 4cfcacbdfe [docs] Fix typo
llvm-svn: 363138
2019-06-12 10:48:33 +00:00
James Henderson 2c16bb8034 [llvm-nm] Fix docs and help text for --print-size
The --print-size help text and documentation claimed that the size was
printed instead of the address, but this is incorrect. It is printed as
well as the address. This patch fixes this issue.

Reviewed by: MaskRay, mtrent, ruiu

Differential Revision: https://reviews.llvm.org/D63142

llvm-svn: 363136
2019-06-12 10:44:41 +00:00
Jordan Rupprecht 4c3722aea8 [docs] Add "GNU binutils Replacements" section to command guide
Summary:
This splits out a section in the command guide for llvm tools that can be used as replacements for GNU tools. For pages that didn't exist, I added stub pages that can be individually filled in by followup patches.

Tested by running `ninja docs-llvm-html` and inspecting locally.

Reviewers: jhenderson, MaskRay, grimar, alexshap

Reviewed By: jhenderson, MaskRay, grimar

Subscribers: smeenai, arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63014

llvm-svn: 363100
2019-06-11 21:13:01 +00:00
James Henderson 5058ae0945 [docs][llvm-nm] Add darwin as --format option
llvm-svn: 363081
2019-06-11 15:58:10 +00:00
James Henderson 224410b7c1 [docs][llvm-nm] Make --help help text consistent with other options
llvm-svn: 363073
2019-06-11 14:55:31 +00:00
James Henderson 9487963244 [llvm-dwarfdump] Simplify --ignore-case help text and documentation
There was a typo in the --ignore-case help text that was copied into the
llvm-dwarfdump command-guide. Additionally, this patch simplifies the
wording, since it was unnecessarily verbose: the switch applies for
searching in general and doesn't need explicitly stating different
search modes (which might go out-of-date as options are added or
removed).

Reviwed by: JDevlieghere

Differential Revision: https://reviews.llvm.org/D63133

llvm-svn: 363066
2019-06-11 13:51:18 +00:00
James Henderson be7f5c7158 [docs][llvm-nm] Fix documentation regarding llvm-nm reading stdin
llvm-nm reads a.out NOT stdin when no input file is specified. This
patch fixes the doc accordingly, and rephrases the surrounding sentence
slightly.

Reviewed by: grimar

Differential Revision: https://reviews.llvm.org/D63135

llvm-svn: 363065
2019-06-11 13:46:52 +00:00
James Henderson d5f38dae59 [llvm-dwarfdump] Add -o to help text and remove --out-file from doc
-o is in the documentation, but not in the llvm-dwarfdump help text.
This patch adds it by inverting the -o and --out-file aliasing. It also
removes --out-file from the documentation, since we don't really want
people to be using this switch in practice.

Reviewed by: aprantl, JDevlieghere, dblaikie

Differential Revision: https://reviews.llvm.org/D63013

llvm-svn: 363044
2019-06-11 10:20:07 +00:00
Matt Davis 41bf444e61 [Docs] [llvm-mca] Point out a caveat for using llvm-mca markers in source code.
Summary: See: https://bugs.llvm.org/show_bug.cgi?id=42173

Reviewers: andreadb, mattd, RKSimon, spatel

Reviewed By: andreadb

Subscribers: tschuett, gbedwell, llvm-commits, andreadb

Tags: #llvm

Patch by Max Marrone (maxpm)! Thanks!

Differential Revision: https://reviews.llvm.org/D63040

llvm-svn: 362979
2019-06-10 20:38:56 +00:00
Alexander Shaposhnikov 85ea2de4b5 [llvm-lipo] Add docs for llvm-lipo
Add docs (llvm-lipo.rst) for llvm-lipo.

Test plan:
make -j8 sphinx 
check that ./docs/html/CommandGuide/llvm-lipo.html is built correctly and looks okay.

Differential revision: https://reviews.llvm.org/D62706

llvm-svn: 362848
2019-06-07 22:03:02 +00:00
James Henderson aa8753bc98 [docs]Move llvm-readobj from "Developer Tools" to "Basic Commands"
On the Command Guide page, there are multiple sections with links to the
different documentation pages available for LLVM tools. The "Basic
Tools" section includes tools like llvm-objdump, llvm-nm and so on. The
"Developer Tools" section contains things like FileCheck and lit. This
change moves llvm-readobj into the former block, from the latter.

Reviewed by: MaskRay

Differential Revision: https://reviews.llvm.org/D63011

llvm-svn: 362813
2019-06-07 16:43:44 +00:00
Thomas Preud'homme 71d3f227a7 FileCheck [6/12]: Introduce numeric variable definition
Summary:
This patch is part of a patch series to add support for FileCheck
numeric expressions. This specific patch introduces support for defining
numeric variable in a CHECK directive.

This commit introduces support for defining numeric variable from a
litteral value in the input text. Numeric expressions can then use the
variable provided it is on a later line.

Copyright:
    - Linaro (changes up to diff 183612 of revision D55940)
    - GraphCore (changes in later versions of revision D55940 and
                 in new revision created off D55940)

Reviewers: jhenderson, chandlerc, jdenny, probinson, grimar, arichardson, rnk

Subscribers: hiraditya, llvm-commits, probinson, dblaikie, grimar, arichardson, tra, rnk, kristina, hfinkel, rogfer01, JonChesterfield

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60386

llvm-svn: 362705
2019-06-06 13:21:06 +00:00
J. Ryan Stinnett d45eaf9405 [Docs] Modernize references to macOS
Summary:
This updates all places in documentation that refer to "Mac OS X", "OS X", etc.
to instead use the modern name "macOS" when no specific version number is
mentioned.

If a specific version is mentioned, this attempts to use the OS name at the time
of that version:

* Mac OS X for 10.0 - 10.7
* OS X for 10.8 - 10.11
* macOS for 10.12 - present

Reviewers: JDevlieghere

Subscribers: mgorny, christof, arphaman, cfe-commits, lldb-commits, libcxx-commits, llvm-commits

Tags: #clang, #lldb, #libc, #llvm

Differential Revision: https://reviews.llvm.org/D62654

llvm-svn: 362113
2019-05-30 16:46:22 +00:00
Thomas Preud'homme 1a944d27b2 FileCheck: Improve FileCheck variable terminology
Summary:
Terminology introduced by [[#]] blocks is confusing and does not
integrate well with existing terminology.

First, variables referred by [[]] blocks are called "pattern variables"
while the text a CHECK directive needs to match is called a "CHECK
pattern". This is inconsistent with variables in [[#]] blocks since
[[#]] blocks are also found in CHECK pattern yet those variables are
called "numeric variable".

Second, the replacing of both [[]] and [[#]] blocks by the value of the
variable or expression they contain is represented by a
FileCheckPatternSubstitution class. The naming refers to being a
substitution in a CHECK pattern but could be wrongly understood as being
a substitution of a pattern variable.

Third and lastly, comments use "numeric expression" to refer both to the
[[#]] blocks as well as to the numeric expressions these blocks contain
which get evaluated at match time.

This patch solves these confusions by
- calling variables in [[]] and [[#]] blocks as string and numeric
  variables respectively;
- referring to [[]] and [[#]] as substitution *blocks*, with the former
  being a string substitution block and the latter a numeric
  substitution block;
- calling [[]] and [[#]] blocks to be replaced by the value of a
  variable or expression they contain a substitution (as opposed to
  definition when these blocks are used to defined a variable), with the
  former being a string substitution and the latter a numeric
  substitution;
- renaming the FileCheckPatternSubstitution as a FileCheckSubstitution
  class with FileCheckStringSubstitution and
  FileCheckNumericSubstitution subclasses;
- restricting the use of "numeric expression" to refer to the expression
  that is evaluated in a numeric substitution.

While numeric substitution blocks only support numeric substitutions of
numeric expressions at the moment there are plans to augment numeric
substitution blocks to support numeric definitions as well as both a
numeric definition and numeric substitution in the same numeric
substitution block.

Reviewers: jhenderson, jdenny, probinson, arichardson

Subscribers: hiraditya, arichardson, probinson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62146

llvm-svn: 361445
2019-05-23 00:10:14 +00:00
Thomas Preud'homme 5c15dbafb9 [FileCheck] Fix sphinx error: Make input be gas block
Summary:
Change example of input text from being llvm block to being gas block
since that text is made-up assembly.

Reviewers: jhenderson, jdenny, probinson, arichardson

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61893

llvm-svn: 360781
2019-05-15 15:20:45 +00:00
Thomas Preud'homme 7b4ecdd3c2 Reinstate "FileCheck [5/12]: Introduce regular numeric variables"
This reinstates r360578 (git e47362c1ec),
reverted in r360653 (git 004393681c),
with a fix for the list added in FileCheck.rst to build without error.

Copyright:
    - Linaro (changes up to diff 183612 of revision D55940)
    - GraphCore (changes in later versions of revision D55940 and
                 in new revision created off D55940)

Reviewers: jhenderson, chandlerc, jdenny, probinson, grimar,
arichardson, rnk

Subscribers: hiraditya, llvm-commits, probinson, dblaikie, grimar,
arichardson, tra, rnk, kristina, hfinkel, rogfer01, JonChesterfield

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60385

llvm-svn: 360665
2019-05-14 11:58:30 +00:00
Thomas Preud'homme 004393681c Revert "FileCheck [5/12]: Introduce regular numeric variables"
This reverts r360578 (git e47362c1ec) to
solve the sphinx build failure on
http://lab.llvm.org:8011/builders/llvm-sphinx-docs buildbot.

llvm-svn: 360653
2019-05-14 08:43:11 +00:00
Thomas Preud'homme e47362c1ec FileCheck [5/12]: Introduce regular numeric variables
Summary:
This patch is part of a patch series to add support for FileCheck
numeric expressions. This specific patch introduces regular numeric
variables which can be set on the command-line.

This commit introduces regular numeric variable that can be set on the
command-line with the -D option to a numeric value. They can then be
used in CHECK patterns in numeric expression with the same shape as
@LINE numeric expression, ie. VAR, VAR+offset or VAR-offset where offset
is an integer literal.

The commit also enable strict whitespace in the verbose.txt testcase to
check that the position or the location diagnostics. It fixes one of the
existing CHECK in the process which was not accurately testing a
location diagnostic (ie. the diagnostic was correct, not the CHECK).

Copyright:
    - Linaro (changes up to diff 183612 of revision D55940)
    - GraphCore (changes in later versions of revision D55940 and
                 in new revision created off D55940)

Reviewers: jhenderson, chandlerc, jdenny, probinson, grimar, arichardson, rnk

Subscribers: hiraditya, llvm-commits, probinson, dblaikie, grimar, arichardson, tra, rnk, kristina, hfinkel, rogfer01, JonChesterfield

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60385

llvm-svn: 360578
2019-05-13 12:39:08 +00:00
Andrea Di Biagio 4e62554bfa [MCA] Add support for nested and overlapping region markers
This patch fixes PR41523
https://bugs.llvm.org/show_bug.cgi?id=41523

Regions can now nest/overlap provided that they have different names.
Anonymous regions cannot overlap.

Region end markers must specify the region name. The only exception is for when
there is only one user-defined region; in that particular case, the region end
marker doesn't need to specify a name.

Incorrect region end markers are no longer ignored. Instead, the tool reports an
error and we exit with an error code.

Added test cases to verify the new diagnostic error messages.

Updated the llvm-mca docs to reflect this feature change.

Differential Revision: https://reviews.llvm.org/D61676

llvm-svn: 360351
2019-05-09 15:18:09 +00:00
Thomas Preud'homme 288ed91e99 FileCheck [4/12]: Introduce @LINE numeric expressions
Summary:
This patch is part of a patch series to add support for FileCheck
numeric expressions. This specific patch introduces the @LINE numeric
expressions.

This commit introduces a new syntax to express a relation a numeric
value in the input text must have with the line number of a given CHECK
pattern: [[#<@LINE numeric expression>]]. Further commits build on that
to express relations between several numeric values in the input text.
To help with naming, regular variables are renamed into pattern
variables and old @LINE expression syntax is referred to as legacy
numeric expression.

Compared to existing @LINE expressions, this new syntax allow arbitrary
spacing between the component of the expression. It offers otherwise the
same functionality but the commit serves to introduce some of the data
structure needed to support more general numeric expressions.

Copyright:
    - Linaro (changes up to diff 183612 of revision D55940)
    - GraphCore (changes in later versions of revision D55940 and
                 in new revision created off D55940)

Reviewers: jhenderson, chandlerc, jdenny, probinson, grimar, arichardson, rnk

Subscribers: hiraditya, llvm-commits, probinson, dblaikie, grimar, arichardson, tra, rnk, kristina, hfinkel, rogfer01, JonChesterfield

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60384

llvm-svn: 359741
2019-05-02 00:04:38 +00:00
Rong Xu b1f9577a5f [llvm-profdata] Fix indentation error in docs. NFC.
llvm-svn: 359625
2019-04-30 22:35:35 +00:00
Rong Xu 287908f9c8 [llvm-profdata] Fix indentation error. NFC
llvm-svn: 359619
2019-04-30 22:05:11 +00:00
Rong Xu 998b97f6f1 [llvm-profdata] Add overlap command to compute similarity b/w two profile files
Add overlap functionality to llvm-profdata tool to compute the similarity
between two profile files.

Differential Revision: https://reviews.llvm.org/D60977

llvm-svn: 359612
2019-04-30 21:19:12 +00:00
Igor Kudrin 99f641ccad [llvm-symbolizer] Add llvm-addr2line
This adds an alias for llvm-symbolizer with different defaults so that
it can be used as a drop-in replacement for GNU's addr2line.

If a substring "addr2line" is found in the tool's name:
  * it defaults "-i", "-f" and "-C" to OFF;
  * it uses "--output-style=GNU" by default.

Differential Revision: https://reviews.llvm.org/D60067

llvm-svn: 358749
2019-04-19 10:17:52 +00:00
Igor Kudrin 1b71b7f3b8 [llvm-symbolizer] Unhide and document the "-output-style" option
With the latest changes, the option gets useful for users of
llvm-symbolizer, not only for the upcoming llvm-addr2line.

Differential Revision: https://reviews.llvm.org/D60816

llvm-svn: 358748
2019-04-19 10:14:18 +00:00
Rong Xu 4f471ee990 [llvm-profdata] Fix one bad format in llvm-profdata CommandGuide doc. NFC
llvm-svn: 358643
2019-04-18 07:11:05 +00:00
Andrea Di Biagio f6a60f1f80 [llvm-mca][scheduler-stats] Print issued micro opcodes per cycle. NFCI
It makes more sense to print out the number of micro opcodes that are issued
every cycle rather than the number of instructions issued per cycle.
This behavior is also consistent with the dispatch-stats: numbers from the two
views can now be easily compared.

llvm-svn: 357919
2019-04-08 16:05:54 +00:00
Guillaume Chatelet 848df5b509 Add an option do not dump the generated object on disk
Reviewers: courbet

Subscribers: llvm-commits, bdb

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60317

llvm-svn: 357769
2019-04-05 15:18:59 +00:00
Roman Lebedev c2423fe689 [llvm-exegesis] Introduce a 'naive' clustering algorithm (PR40880)
Summary:
This is an alternative to D59539.

Let's suppose we have measured 4 different opcodes, and got: `0.5`, `1.0`, `1.5`, `2.0`.
Let's suppose we are using `-analysis-clustering-epsilon=0.5`.
By default now we will start processing the `0.5` point, find that `1.0` is it's neighbor, add them to a new cluster.
Then we will notice that `1.5` is a neighbor of `1.0` and add it to that same cluster.
Then we will notice that `2.0` is a neighbor of `1.5` and add it to that same cluster.
So all these points ended up in the same cluster.
This may or may not be a correct implementation of dbscan clustering algorithm.

But this is rather horribly broken for the reasons of comparing the clusters with the LLVM sched data.
Let's suppose all those opcodes are currently in the same sched cluster.
If i specify `-analysis-inconsistency-epsilon=0.5`, then no matter
the LLVM values this cluster will **never** match the LLVM values,
and thus this cluster will **always** be displayed as inconsistent.

The solution is obviously to split off some of these opcodes into different sched cluster.
But how do i do that? Out of 4 opcodes displayed in the inconsistency report,
which ones are the "bad ones"? Which ones are the most different from the checked-in data?
I'd need to go in to the `.yaml` and look it up manually.

The trivial solution is to, when creating clusters, don't use the full dbscan algorithm,
but instead "pick some unclustered point, pick all unclustered points that are it's neighbor,
put them all into a new cluster, repeat". And just so as it happens, we can arrive
at that algorithm by not performing the "add neighbors of a neighbor to the cluster" step.

But that won't work well once we teach analyze mode to operate in on-1D mode
(i.e. on more than a single measurement type at a time), because the clustering would
depend on the order of the measurements.

Instead, let's just create a single cluster per opcode, and put all the points of that opcode into said cluster.
And simultaneously check that every point in that cluster is a neighbor of every other point in the cluster,
and if they are not, the cluster (==opcode) is unstable.

This is //yet another// step to bring me closer to being able to continue cleanup of bdver2 sched model..

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=40880 | PR40880 ]].

Reviewers: courbet, gchatelet

Reviewed By: courbet

Subscribers: tschuett, jdoerfert, RKSimon, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59820

llvm-svn: 357152
2019-03-28 08:55:01 +00:00
Francis Visoiu Mistrih ee1a6e70fa [Remarks] Emit a section containing remark diagnostics metadata
A section containing metadata on remark diagnostics will be emitted if
the flag (-mllvm) -remarks-section is present.

For now, the metadata is:

* a magic number for remarks: "REMARKS\0"
* the version number: a little-endian uint64_t
* the absolute file path to the serialized remark diagnostics: a
  null-terminated string.

Differential Revision: https://reviews.llvm.org/D59571

llvm-svn: 357043
2019-03-27 01:13:59 +00:00
Max Moroz a80d9ce5cf 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
Andrea Di Biagio be3281a281 [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
Rong Xu a6ff69f6dd [PGO] Context sensitive PGO (part 2)
Part 2 of CSPGO changes (mostly related to ProfileSummary).
Note that I use a default parameter in setProfileSummary() and getSummary().
This is to break the dependency in clang. I will make the parameter explicit
after changing clang in a separated patch.

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

llvm-svn: 355131
2019-02-28 19:55:07 +00:00
Roman Lebedev 542e5d7bb5 [llvm-exegesis] Split Epsilon param into two (PR40787)
Summary:
This eps param is used for two distinct things:
* initial point clusterization
* checking clusters against the llvm values

What if one wants to only look at highly different clusters, without changing
the clustering itself? In particular, this helps to weed out noisy measurements
(since the clusterization epsilon is still small, so there is a better chance
that noisy measurements from the same opcode will go into different clusters)

By splitting it into two params it is now possible.

This is nearly-free performance-wise:
Old:
```
$ perf stat -r 25 ./bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency-1.yaml -analysis-inconsistencies-output-file=/tmp/clusters-old.html
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 10099 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-old.html'
...
 Performance counter stats for './bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency-1.yaml -analysis-inconsistencies-output-file=/tmp/clusters-old.html' (25 runs):

            390.01 msec task-clock                #    0.998 CPUs utilized            ( +-  0.25% )
                12      context-switches          #   31.735 M/sec                    ( +- 27.38% )
                 0      cpu-migrations            #    0.000 K/sec
              4745      page-faults               # 12183.732 M/sec                   ( +-  0.54% )
        1562711900      cycles                    # 4012303.327 GHz                   ( +-  0.24% )  (82.90%)
         185567822      stalled-cycles-frontend   #   11.87% frontend cycles idle     ( +-  0.52% )  (83.30%)
         392106234      stalled-cycles-backend    #   25.09% backend cycles idle      ( +-  1.31% )  (33.79%)
        1839236666      instructions              #    1.18  insn per cycle
                                                  #    0.21  stalled cycles per insn  ( +-  0.15% )  (50.37%)
         407035764      branches                  # 1045074878.710 M/sec              ( +-  0.12% )  (66.80%)
          10896459      branch-misses             #    2.68% of all branches          ( +-  0.17% )  (83.20%)

          0.390629 +- 0.000972 seconds time elapsed  ( +-  0.25% )
```
```
$ perf stat -r 9 ./bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency.yml -analysis-inconsistencies-output-file=/tmp/clusters-old.html
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 50572 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-old.html'
...
 Performance counter stats for './bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency.yml -analysis-inconsistencies-output-file=/tmp/clusters-old.html' (9 runs):

           6803.36 msec task-clock                #    0.999 CPUs utilized            ( +-  0.96% )
               262      context-switches          #   38.546 M/sec                    ( +- 23.06% )
                 0      cpu-migrations            #    0.065 M/sec                    ( +- 76.03% )
             13287      page-faults               # 1953.206 M/sec                    ( +-  0.32% )
       27252537904      cycles                    # 4006024.257 GHz                   ( +-  0.95% )  (83.31%)
        1496314935      stalled-cycles-frontend   #    5.49% frontend cycles idle     ( +-  0.97% )  (83.32%)
       16128404524      stalled-cycles-backend    #   59.18% backend cycles idle      ( +-  0.30% )  (33.37%)
       17611143370      instructions              #    0.65  insn per cycle
                                                  #    0.92  stalled cycles per insn  ( +-  0.05% )  (50.04%)
        3894906599      branches                  # 572537147.437 M/sec               ( +-  0.03% )  (66.69%)
         116314514      branch-misses             #    2.99% of all branches          ( +-  0.20% )  (83.35%)

            6.8118 +- 0.0689 seconds time elapsed  ( +-  1.01%)
```
New:
```
$ perf stat -r 25 ./bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency-1.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new.html
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 10099 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new.html'
...
 Performance counter stats for './bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency-1.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new.html' (25 runs):

            400.14 msec task-clock                #    0.998 CPUs utilized            ( +-  0.66% )
                12      context-switches          #   29.429 M/sec                    ( +- 25.95% )
                 0      cpu-migrations            #    0.100 M/sec                    ( +-100.00% )
              4714      page-faults               # 11796.496 M/sec                   ( +-  0.55% )
        1603131306      cycles                    # 4011840.105 GHz                   ( +-  0.66% )  (82.85%)
         199538509      stalled-cycles-frontend   #   12.45% frontend cycles idle     ( +-  2.40% )  (83.10%)
         402249109      stalled-cycles-backend    #   25.09% backend cycles idle      ( +-  1.19% )  (34.05%)
        1847783963      instructions              #    1.15  insn per cycle
                                                  #    0.22  stalled cycles per insn  ( +-  0.18% )  (50.64%)
         407162722      branches                  # 1018925730.631 M/sec              ( +-  0.12% )  (67.02%)
          10932779      branch-misses             #    2.69% of all branches          ( +-  0.51% )  (83.28%)

           0.40077 +- 0.00267 seconds time elapsed  ( +-  0.67% )

lebedevri@pini-pini:/build/llvm-build-Clang-release$ perf stat -r 9 ./bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency.yml -analysis-inconsistencies-output-file=/tmp/clusters-new.html
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 50572 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new.html'
...
 Performance counter stats for './bin/llvm-exegesis -mode=analysis -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-latency.yml -analysis-inconsistencies-output-file=/tmp/clusters-new.html' (9 runs):

           6947.79 msec task-clock                #    1.000 CPUs utilized            ( +-  0.90% )
               217      context-switches          #   31.236 M/sec                    ( +- 36.16% )
                 1      cpu-migrations            #    0.096 M/sec                    ( +- 50.00% )
             13258      page-faults               # 1908.389 M/sec                    ( +-  0.34% )
       27830796523      cycles                    # 4006032.286 GHz                   ( +-  0.89% )  (83.30%)
        1504554006      stalled-cycles-frontend   #    5.41% frontend cycles idle     ( +-  2.10% )  (83.32%)
       16716574843      stalled-cycles-backend    #   60.07% backend cycles idle      ( +-  0.65% )  (33.38%)
       17755545931      instructions              #    0.64  insn per cycle
                                                  #    0.94  stalled cycles per insn  ( +-  0.09% )  (50.04%)
        3897255686      branches                  # 560980426.597 M/sec               ( +-  0.06% )  (66.70%)
         117045395      branch-misses             #    3.00% of all branches          ( +-  0.47% )  (83.34%)

            6.9507 +- 0.0627 seconds time elapsed  ( +-  0.90% )
```

I.e. it's +2.6% slowdown for one whole sweep, or +2% for 5 whole sweeps.
Within noise i'd say.

Should help with [[ https://bugs.llvm.org/show_bug.cgi?id=40787 | PR40787 ]].

Reviewers: courbet, gchatelet

Reviewed By: courbet

Subscribers: tschuett, RKSimon, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58476

llvm-svn: 354767
2019-02-25 09:36:12 +00:00
Roman Lebedev 69716394f3 [llvm-exegesis] Opcode stabilization / reclusterization (PR40715)
Summary:
Given an instruction `Opcode`, we can make benchmarks (measurements) of the
instruction characteristics/performance. Then, to facilitate further analysis
we group the benchmarks with *similar* characteristics into clusters.
Now, this is all not entirely deterministic. Some instructions have variable
characteristics, depending on their arguments. And thus, if we do several
benchmarks of the same instruction `Opcode`, we may end up with *different*
performance characteristics measurements. And when we then do clustering,
these several benchmarks of the same instruction `Opcode` may end up being
clustered into *different* clusters. This is not great for further analysis.

We shall find every `Opcode` with benchmarks not in just one cluster, and move
*all* the benchmarks of said `Opcode` into one new unstable cluster per `Opcode`.

I have solved this by making `ClusterId` a bit field, adding a `IsUnstable` bit,
and introducing `-analysis-display-unstable-clusters` switch to toggle between
displaying stable-only clusters and unstable-only clusters.

The reclusterization is deterministically stable, produces identical reports
between runs. (Or at least that is what i'm seeing, maybe it isn't)

Timings/comparisons:
old (current trunk/head) {F8303582}
```
$ perf stat -r 25 ./bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-old.html
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-old.html'
...
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-old.html'

 Performance counter stats for './bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-old.html' (25 runs):

           6624.73 msec task-clock                #    0.999 CPUs utilized            ( +-  0.53% )
               172      context-switches          #   25.965 M/sec                    ( +- 29.89% )
                 0      cpu-migrations            #    0.042 M/sec                    ( +- 56.54% )
             31073      page-faults               # 4690.754 M/sec                    ( +-  0.08% )
       26538711696      cycles                    # 4006230.292 GHz                   ( +-  0.53% )  (83.31%)
        2017496807      stalled-cycles-frontend   #    7.60% frontend cycles idle     ( +-  0.93% )  (83.32%)
       13403650062      stalled-cycles-backend    #   50.51% backend cycles idle      ( +-  0.33% )  (33.37%)
       19770706799      instructions              #    0.74  insn per cycle
                                                  #    0.68  stalled cycles per insn  ( +-  0.04% )  (50.04%)
        4419821812      branches                  # 667207369.714 M/sec               ( +-  0.03% )  (66.69%)
         121741669      branch-misses             #    2.75% of all branches          ( +-  0.28% )  (83.34%)

            6.6283 +- 0.0358 seconds time elapsed  ( +-  0.54% )
```

patch, with reclustering but without filtering (i.e. outputting all the stable *and* unstable clusters) {F8303586}
```
$ perf stat -r 25 ./bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new-all.html
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new-all.html'
...
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new-all.html'

 Performance counter stats for './bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new-all.html' (25 runs):

           6475.29 msec task-clock                #    0.999 CPUs utilized            ( +-  0.31% )
               213      context-switches          #   32.952 M/sec                    ( +- 23.81% )
                 1      cpu-migrations            #    0.130 M/sec                    ( +- 43.84% )
             31287      page-faults               # 4832.057 M/sec                    ( +-  0.08% )
       25939086577      cycles                    # 4006160.279 GHz                   ( +-  0.31% )  (83.31%)
        1958812858      stalled-cycles-frontend   #    7.55% frontend cycles idle     ( +-  0.68% )  (83.32%)
       13218961512      stalled-cycles-backend    #   50.96% backend cycles idle      ( +-  0.29% )  (33.37%)
       19752995402      instructions              #    0.76  insn per cycle
                                                  #    0.67  stalled cycles per insn  ( +-  0.04% )  (50.04%)
        4417079244      branches                  # 682195472.305 M/sec               ( +-  0.03% )  (66.70%)
         121510065      branch-misses             #    2.75% of all branches          ( +-  0.19% )  (83.34%)

            6.4832 +- 0.0229 seconds time elapsed  ( +-  0.35% )
```
Funnily, *this* measurement shows that said reclustering actually improved performance.

patch, with reclustering, only the stable clusters {F8303594}
```
$ perf stat -r 25 ./bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new-stable.html
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new-stable.html'
...
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new-stable.html'

 Performance counter stats for './bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new-stable.html' (25 runs):

           6387.71 msec task-clock                #    0.999 CPUs utilized            ( +-  0.13% )
               133      context-switches          #   20.792 M/sec                    ( +- 23.39% )
                 0      cpu-migrations            #    0.063 M/sec                    ( +- 61.24% )
             31318      page-faults               # 4903.256 M/sec                    ( +-  0.08% )
       25591984967      cycles                    # 4006786.266 GHz                   ( +-  0.13% )  (83.31%)
        1881234904      stalled-cycles-frontend   #    7.35% frontend cycles idle     ( +-  0.25% )  (83.33%)
       13209749965      stalled-cycles-backend    #   51.62% backend cycles idle      ( +-  0.16% )  (33.36%)
       19767554347      instructions              #    0.77  insn per cycle
                                                  #    0.67  stalled cycles per insn  ( +-  0.04% )  (50.03%)
        4417480305      branches                  # 691618858.046 M/sec               ( +-  0.03% )  (66.68%)
         118676358      branch-misses             #    2.69% of all branches          ( +-  0.07% )  (83.33%)

            6.3954 +- 0.0118 seconds time elapsed  ( +-  0.18% )
```
Performance improved even further?! Makes sense i guess, less clusters to print.

patch, with reclustering, only the unstable clusters {F8303601}
```
$ perf stat -r 25 ./bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new-unstable.html -analysis-display-unstable-clusters
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new-unstable.html'
...
no exegesis target for x86_64-unknown-linux-gnu, using default
Parsed 43970 benchmark points
Printing sched class consistency analysis results to file '/tmp/clusters-new-unstable.html'

 Performance counter stats for './bin/llvm-exegesis -mode=analysis -analysis-epsilon=0.5 -benchmarks-file=/home/lebedevri/PileDriver-Sched/benchmarks-inverse_throughput.yaml -analysis-inconsistencies-output-file=/tmp/clusters-new-unstable.html -analysis-display-unstable-clusters' (25 runs):

           6124.96 msec task-clock                #    1.000 CPUs utilized            ( +-  0.20% )
               194      context-switches          #   31.709 M/sec                    ( +- 20.46% )
                 0      cpu-migrations            #    0.039 M/sec                    ( +- 49.77% )
             31413      page-faults               # 5129.261 M/sec                    ( +-  0.06% )
       24536794267      cycles                    # 4006425.858 GHz                   ( +-  0.19% )  (83.31%)
        1676085087      stalled-cycles-frontend   #    6.83% frontend cycles idle     ( +-  0.46% )  (83.32%)
       13035595603      stalled-cycles-backend    #   53.13% backend cycles idle      ( +-  0.16% )  (33.36%)
       18260877653      instructions              #    0.74  insn per cycle
                                                  #    0.71  stalled cycles per insn  ( +-  0.05% )  (50.03%)
        4112411983      branches                  # 671484364.603 M/sec               ( +-  0.03% )  (66.68%)
         114066929      branch-misses             #    2.77% of all branches          ( +-  0.11% )  (83.32%)

            6.1278 +- 0.0121 seconds time elapsed  ( +-  0.20% )
```
This tells us that the actual `-analysis-inconsistencies-output-file=` outputting only takes ~0.4 sec for 43970 benchmark points (3 whole sweeps)
(Also, wow this is fast, it used to take several minutes originally)

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=40715 | PR40715 ]].

Reviewers: courbet, gchatelet

Reviewed By: courbet

Subscribers: tschuett, jdoerfert, llvm-commits, RKSimon

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58355

llvm-svn: 354441
2019-02-20 09:14:04 +00:00
Vedant Kumar a0b9725479 [llvm-cov] Add support for gcov --hash-filenames option
The patch adds support for --hash-filenames to llvm-cov. This option adds md5
hash of the source path to the name of the generated .gcov file. The option is
crucial for cases where you have multiple files with the same name but can't
use --preserve-paths as resulting filenames exceed the limit.

from gcov(1):

```
-x
--hash-filenames
    By default, gcov uses the full pathname of the source files to to
    create an output filename.  This can lead to long filenames that
    can overflow filesystem limits.  This option creates names of the
    form source-file##md5.gcov, where the source-file component is
    the final filename part and the md5 component is calculated from
    the full mangled name that would have been used otherwise.
```

Patch by Igor Ignatev!

Differential Revision: https://reviews.llvm.org/D58370

llvm-svn: 354379
2019-02-19 20:45:00 +00:00
Guillaume Chatelet bd604e011f [llvm-exegesis] [NFC] Fixing typo.
Reviewers: courbet, gchatelet

Reviewed By: courbet, gchatelet

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D54895

llvm-svn: 354250
2019-02-18 10:08:20 +00:00
Roman Lebedev 21193f4b7e [llvm-exegesis] Don't default to running&dumping all analyses to '-'
Summary:
Up until the point i have looked in the source, i didn't even understood that
i can disable 'cluster' output. I have always silenced it via ` &> /dev/null`.
(And hoped it wasn't contributing much of the run time.)

While i expect that it has it's use-cases i never once needed it so far.
If i forget to silence it, console is completely flooded with that output.

How about not expecting users to opt-out of analyses,
but to explicitly specify the analyses that should be performed?

Reviewers: courbet, gchatelet

Reviewed By: courbet

Subscribers: tschuett, RKSimon, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57648

llvm-svn: 353021
2019-02-04 09:12:08 +00:00
Clement Courbet 362653f7af [llvm-exegesis] Add throughput mode.
Summary:
This just uses the latency benchmark runner on the parallel uops snippet
generator.

Fixes PR37698.

Reviewers: gchatelet

Subscribers: tschuett, RKSimon, llvm-commits

Differential Revision: https://reviews.llvm.org/D57000

llvm-svn: 352632
2019-01-30 16:02:20 +00:00
James Henderson 6f39f6ace7 [llvm-symbolizer][doc] Tweak wording of --adjust-vma switch description
The address isn't dynamically relocated. The object is.

llvm-svn: 352477
2019-01-29 10:43:48 +00:00