942 Commits

Author SHA1 Message Date
Yuanfang Chen
bf8086d1c1 [llc] (almost) remove --print-machineinstrs
Its effect could be achieved by
`-stop-after`,`-print-after`,`-print-after-all`. But a few tests need to
print MIR after ISel which could not be done with
`-print-after`/`-stop-after` since isel pass does not have commandline name.
That's the reason `--print-machineinstrs` is downgraded to
`--print-after-isel` in this patch. `--print-after-isel` could be
removed after we switch to new pass manager since isel pass would have a
commandline text name to use `print-after` or equivalent switches.

The motivation of this patch is to reduce tests dependency on
would-be-deprecated feature.

Reviewed By: arsenm, dsanders

Differential Revision: https://reviews.llvm.org/D83275
2020-07-20 10:43:28 -07:00
Elvina Yakubova
9d37b40f76 [llvm-readobj] Print error when executed with no input files
This patch changes llvm-readelf (and llvm-readobj for consistency)
behavior to print an error when executed with no input files.

Reading from stdin can be achieved via a '-' for the input
object.

Fixes https://bugs.llvm.org/show_bug.cgi?id=46400

Differential Revision: https://reviews.llvm.org/D83704

Reviewed by: jhenderson, MaskRay, sbc, jyknight
2020-07-20 10:39:05 +01:00
Sameer Arora
4336e89619 Introducing llvm-libtool-darwin
This diff starts the implementation of llvm-libtool-darwin
(an llvm based replacement of cctool's libtool).
Libtool is used for creating static and dynamic libraries
from a bunch of object files given as input.

Reviewed by alexshap, smeenai, jhenderson, MaskRay

Differential Revision: https://reviews.llvm.org/D82923
2020-07-17 08:07:02 -07:00
Clement Courbet
17ad6e2f24 Revert "[llvm-exegesis] Add benchmark latency option on X86 that uses LBR for more precise measurements."
From @erichkeane:
```
This patch doesn't seem to build for me:
/iusers/ekeane1/workspaces/llvm-project/llvm/tools/llvm-exegesis/lib/X86/X86Counter.cpp: In function ‘llvm::Error llvm::exegesis::parseDataBuffer(const char*, size_t, const void*, const void*, llvm::SmallVector<long int, 4>*)’:
/iusers/ekeane1/workspaces/llvm-project/llvm/tools/llvm-exegesis/lib/X86/X86Counter.cpp:99:37: error: ‘struct perf_branch_entry’ has no member named ‘cycles’

CycleArray->push_back(Entry.cycles);
I'm on RHEL7, so I have kernel 3.10, so it doesn't have 'cycles'.

According ot this: https://elixir.bootlin.com/linux/v4.3/source/include/uapi/linux/perf_event.h#L963 kernel 4.3 is the first time that 'cycles' appeared in this structure.
```
2020-07-17 16:55:17 +02:00
Jinsong Ji
f958fcb9e1 [docs] fix ident in llvm-exegesis.rst 2020-07-16 17:30:09 +00:00
Vy Nguyen
86e9087897 [llvm-exegesis] Add benchmark latency option on X86 that uses LBR for more precise measurements.
Starting with Skylake, the LBR contains the precise number of cycles between the two
    consecutive branches.
    Making use of this will hopefully make the measurements more precise than the
    existing methods of using RDTSC.

            Differential Revision: https://reviews.llvm.org/D77422
2020-07-16 12:12:46 -04:00
Joel E. Denny
45343bf20f [FileCheck] Fix up -dump-input* docs
In FileCheck.rst, add `-dump-input-context` and `-dump-input-filter`,
and fix some `-dump-input` documentation.

In `FileCheck -help`, `cl::value_desc("kind")` is being ignored for
`-dump-input-filter`, so just drop it.

Extend `-dump-input=help` to mention FILECHECK_OPTS.
2020-07-10 17:21:01 -04:00
Oliver Stannard
e53ceb3dc0 [llvm-objdump] Display locations of variables alongside disassembly
This adds the --debug-vars option to llvm-objdump, which prints
locations (registers/memory) of source-level variables alongside the
disassembly based on DWARF info. A vertical line is printed for each
live-range, with a label at the top giving the variable name and
location, and the position and length of the line indicating the program
counter range in which it is valid.

Differential revision: https://reviews.llvm.org/D70720
2020-07-09 09:58:00 +01:00
Nico Weber
ae4d21baa4 fix typos to cycle bots 2020-07-06 20:37:11 -04:00
Mike Edwards
5e9ac43a7a [LIT] Correcting max-failures option in lit documentation. 2020-06-27 14:57:04 -07:00
Djordje Todorovic
c0e9a51908 [docs][llvm-dwarfdump] Fix the warnings during docs-llvm-html buil
Before the fix the build of docs-llvm-html would fail.
The D80959 introduced options that are not recognized, so we have
warning as:

  llvm-project/llvm/docs/CommandGuide/llvm-dwarfdump.rst:40\
  :unknown option: --debug-info

Differential Revision: https://reviews.llvm.org/D82460
2020-06-25 11:04:28 +02:00
Peter Collingbourne
7d1cbe5a8a llvm-nm: Implement --special-syms.
Differential Revision: https://reviews.llvm.org/D82251
2020-06-22 13:05:47 -07:00
Zequan Wu
7549421f49 [llvm-readobj] set --elf-cg-profile as alias of --cg-profile
Summary: Rename --elf-cg-profile to --cg-profile and keep --elf-cg-profile as an alias of --cg-profile.

Reviewers: jhenderson, MaskRay, espindola, hans

Reviewed By: jhenderson, MaskRay

Subscribers: emaste, rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81855
2020-06-17 11:24:45 -07:00
Paul Walker
1b3768875a [FileCheck] Implement * and / operators for ExpressionValue.
Subscribers: arichardson, hiraditya, thopre, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80915
2020-06-17 09:39:17 +00:00
Cyndy Ishida
fd46376e35 [llvm][llvm-nm] add TextAPI/MachO support
Summary:
This completes the needed glueing to support reading tbd files from nm.
This includes specifying which slice filtering with `--arch` and a new
option specifically for tbd files `--add-inlinedinfo` which will show
the reexported libraries that are appended in the tbd file.

Reviewers: ributzka, steven_wu, JDevlieghere, jhenderson

Reviewed By: JDevlieghere

Subscribers: hiraditya, MaskRay, dexonsmith, rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81614
2020-06-11 18:54:16 -07:00
Thomas Preud'homme
a5f3d35feb FileCheck [11/12]: Add matching constraint specification
This patch is part of a patch series to add support for FileCheck
numeric expressions. This specific patch adds support for specifying the
matching constraint for a numeric expression, ie. how the value being
matched should relate to the numeric expression.

This commit only adds the equality constraint where the numeric value
matched must be equal to the numeric expression. It is the default
matching constraint used when not specified. It is added to provision
other matching constraint (e.g. inequality relations).

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)

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D60391
2020-06-10 15:56:10 +01:00
Paul Walker
a8c59c6124 [FileCheck] Add function call support to numerical expressions.
This patch extends numerical expressions to allow calls to
predefined functions. These calls can be combined with the
existing numerical operators, which includes nesting calls.

The call syntax is:

  <func>(<args>)

Where <func> is a predefined string literal, currently limited to
one of add, max, min and sub. <arg> is a comma seperated list of
numerical expressions.

Subscribers: arichardson, hiraditya, thopre, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79936
2020-06-10 09:42:00 +00:00
Mehdi Amini
ed76433842 Change filecheck default to dump input on failure
Having the input dumped on failure seems like a better
default: I debugged FileCheck tests for a while without knowing
about this option, which really helps to understand failures.

Remove `-dump-input-on-failure` and the environment variable
FILECHECK_DUMP_INPUT_ON_FAILURE which are now obsolete.

Differential Revision: https://reviews.llvm.org/D81422
2020-06-09 18:57:46 +00:00
Sanjay Patel
f8f4aec997 [Docs] fix typos for llvm-mca; NFC 2020-06-07 11:14:24 -04:00
Mike Edwards
1e5cc34a44 [LIT] NFC adding max-failures option to lit documentation.
Differential Revision: https://reviews.llvm.org/D81337
2020-06-06 18:26:45 -07:00
Jonas Devlieghere
2b24554801 [llvm-dwarfdump] Print [=<offset>] after --debug-* options in help output.
Some of the --debug-* options can take an optional offset. Although the
man page does a good job of making that clear, it's much harder to
discover from the help output.

Currently the only reference to this is the following sentence:

> Where applicable these parameters take an optional =<offset> argument
> to dump only the entry at the specified offset.

This patch changes the help output from to print [=<offset>] after the
options that take an offset.

  --debug-info[=<offset>]    - Dump the .debug_info section

rdar://problem/63150066

Differential revision: https://reviews.llvm.org/D80959
2020-06-02 11:06:11 -07:00
Thomas Preud'homme
959d70cd6e FileCheck [10/12]: Add support for signed numeric values
Summary:
This patch is part of a patch series to add support for FileCheck
numeric expressions. This specific patch adds support signed numeric
values, thus allowing negative numeric values.

As such, the patch adds a new class to represent a signed or unsigned
value and add the logic for type promotion and type conversion in
numeric expression mixing signed and unsigned values. It also adds
the %d format specifier to represent signed value.

Finally, it also adds underflow and overflow detection when performing a
binary operation.

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

Reviewed By: jhenderson, arichardson

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60390
2020-05-28 10:44:21 +01:00
Alex Richardson
aa7eac2e43 [FileCheck] Allow parenthesized expressions
With this change it is be possible to write FileCheck expressions such
as [[#(VAR+1)-2]]. Currently, the only supported arithmetic operators are
plus and minus, so this is not particularly useful yet. However, it our
CHERI fork we have tests that benefit from having multiplication in
FileCheck expressions. Allowing parenthesized expressions is the simplest
way for us to work around the current lack of operator precedence in
FileCheck expressions.

Reviewed By: thopre, jhenderson
Differential Revision: https://reviews.llvm.org/D77383
2020-05-27 16:31:39 +01:00
Alexander Shaposhnikov
372d313844 [llvm-objcopy][MachO] Add support for removing Swift symbols
cctools strip has the option "-T" which removes Swift symbols.
This diff implements this option in llvm-strip for MachO.

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D80099
2020-05-26 16:49:56 -07:00
Jinsong Ji
fa4ec092cd [docs][llvm-extract] Add missing alias/bb options
llvm-extract get serveral new options, but we forgot to update doc.
This patch update the doc.

Reviewed By: volkan

Differential Revision: https://reviews.llvm.org/D80413
2020-05-22 03:52:07 +00:00
Jonas Devlieghere
b03521b98d [dsymutil] Add reproducers to dsymutil
Add support for generating a dsymutil reproducer. The result is a folder
containing all the object files for linking.

When --gen-reproducer is passed, dsymutil uses a FileCollectorFileSystem
which keeps track of all the files used by dsymutil. These files are
copied into a temporary directory when dsymutil exists.

When this path is passed to --use-reproducer, dsymutil uses a
RedirectingFileSystem that will use the files from the reproducer
directory instead of the actual paths. This means you don't need to mess
with the OSO path prefix.

Differential revision: https://reviews.llvm.org/D79398
2020-05-21 10:59:49 -07:00
Jonas Devlieghere
028966e9eb [dsymutil] Make sure the --help output and man page are consistent
As suggested by Adrian in D79398.
2020-05-18 11:38:36 -07:00
Wei Mi
0220efbbe5 [llvm-profdata] Update CommandGuide
Add a bunch of SampleFDO related flags added recently into llvm-profdata to
its command guide.

Differential Revision: https://reviews.llvm.org/D79911
2020-05-14 13:59:42 -07:00
Joel E. Denny
f717458fdf [FileCheck] Support comment directives
Sometimes you want to disable a FileCheck directive without removing
it entirely, or you want to write comments that mention a directive by
name.  The `COM:` directive makes it easy to do this.  For example,
you might have:

```
; X32: pinsrd_1:
; X32:    pinsrd $1, 4(%esp), %xmm0

; COM: FIXME: X64 isn't working correctly yet for this part of codegen, but
; COM: X64 will have something similar to X32:
; COM:
; COM:   X64: pinsrd_1:
; COM:   X64:    pinsrd $1, %edi, %xmm0
```

Without this patch, you need to use some combination of rewording and
directive syntax mangling to prevent FileCheck from recognizing the
commented occurrences of `X32:` and `X64:` above as directives.
Moreover, FileCheck diagnostics have been proposed that might complain
about the occurrences of `X64` that don't have the trailing `:`
because they look like directive typos:

  <http://lists.llvm.org/pipermail/llvm-dev/2020-April/140610.html>

I think dodging all these problems can prove tedious for test authors,
and directive syntax mangling already makes the purpose of existing
test code unclear.  `COM:` can avoid all these problems.

This patch also updates the small set of existing tests that define
`COM` as a check prefix:

- clang/test/CodeGen/default-address-space.c
- clang/test/CodeGenOpenCL/addr-space-struct-arg.cl
- clang/test/Driver/hip-device-libs.hip
- llvm/test/Assembler/drop-debug-info-nonzero-alloca.ll

I think lit should support `COM:` as well.  Perhaps `clang -verify`
should too.

Reviewed By: jhenderson, thopre

Differential Revision: https://reviews.llvm.org/D79276
2020-05-13 11:29:48 -04:00
Joel E. Denny
2412893f8a Revert "[FileCheck] Support comment directives"
This reverts commit 9a9a5f9893c8db05cebc8818eb8485bff61f7c74 to try to
fix a bot:

http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/23489
2020-05-11 19:41:22 -04:00
Joel E. Denny
efde2f4800 [FileCheck] Support comment directives
Sometimes you want to disable a FileCheck directive without removing
it entirely, or you want to write comments that mention a directive by
name.  The `COM:` directive makes it easy to do this.  For example,
you might have:

```
; X32: pinsrd_1:
; X32:    pinsrd $1, 4(%esp), %xmm0

; COM: FIXME: X64 isn't working correctly yet for this part of codegen, but
; COM: X64 will have something similar to X32:
; COM:
; COM:   X64: pinsrd_1:
; COM:   X64:    pinsrd $1, %edi, %xmm0
```

Without this patch, you need to use some combination of rewording and
directive syntax mangling to prevent FileCheck from recognizing the
commented occurrences of `X32:` and `X64:` above as directives.
Moreover, FileCheck diagnostics have been proposed that might complain
about the occurrences of `X64` that don't have the trailing `:`
because they look like directive typos:

  <http://lists.llvm.org/pipermail/llvm-dev/2020-April/140610.html>

I think dodging all these problems can prove tedious for test authors,
and directive syntax mangling already makes the purpose of existing
test code unclear.  `COM:` can avoid all these problems.

This patch also updates the small set of existing tests that define
`COM` as a check prefix:

- clang/test/CodeGen/default-address-space.c
- clang/test/CodeGenOpenCL/addr-space-struct-arg.cl
- clang/test/Driver/hip-device-libs.hip
- llvm/test/Assembler/drop-debug-info-nonzero-alloca.ll

I think lit should support `COM:` as well.  Perhaps `clang -verify`
should too.

Reviewed By: jhenderson, thopre

Differential Revision: https://reviews.llvm.org/D79276
2020-05-11 14:53:48 -04:00
Jonas Devlieghere
5e66aeab68 [dsymutil] Add option to print statistics about the .debug_info size.
This patch adds statistics about the contribution of each object file to
the linked debug info. When --statistics is passed to dsymutil, it
prints a table after linking as illustrated below.

It lists the object file name, the size of the debug info in the object
file in bytes, and the absolute size contribution to the linked dSYM and
the percentage difference. The table is sorted by the output size, so
the object files contributing the most to the link are listed first.

.debug_info section size (in bytes)
-------------------------------------------------------------------------------
Filename                                           Object         dSYM   Change
-------------------------------------------------------------------------------
basic2.macho.x86_64.o                                210b         165b  -24.00%
basic3.macho.x86_64.o                                177b         150b  -16.51%
basic1.macho.x86_64.o                                125b         129b    3.15%
-------------------------------------------------------------------------------
Total                                                512b         444b  -14.23%
-------------------------------------------------------------------------------

Differential revision: https://reviews.llvm.org/D79513
2020-05-06 19:48:45 -07:00
James Henderson
637a5f9e5d [docs][llvm-objcopy] Update --output-target text with right defaults
The --output-target documentation has slightly rotted, as the default is
no longer purely based on the input file format, but also the value of
--input-target. This patch updates the documentation to make this
explicit.

Reviewed by: MaskRay, alexshap

Differential Revision: https://reviews.llvm.org/D79318
2020-05-05 11:22:56 +01:00
Djordje Todorovic
c074cdefc8 [llvm-dwarfdump][Stats] Clean up
This addresses:
  -Clean up the source code
  -Refactor the JSON fields
  -Fix the test cases
  -Improve the docs for the stats output

Differential Revision: https://reviews.llvm.org/D77789
2020-05-04 09:35:40 +02:00
Thomas Preud'homme
02fe8358c1 [docs][FileCheck] Fix invalid example
Summary:
FileCheck documentation contains an example of a numeric variable
defined and used on the same line. This is not currently supported by
FileCheck so this commit fixes the example to use CHECK-SAME for the
variable use.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D79253
2020-05-02 23:31:18 +01:00
James Henderson
40096a8dfd [docs][llvm-cxxfilt] Document --no-strip-underscore option
This option was added several months ago in commit e84468c1.

Reviewed by: MaskRay, erik.pilkington, steven_wu

Differential Revision: https://reviews.llvm.org/D79166
2020-05-01 11:03:06 +01:00
James Henderson
0082b94912 [docs][llvm-cxxfilt] Fix indentation in rst file
This makes it consistent throughout the options, although the end result
is unchanged.
2020-04-30 10:41:45 +01:00
Jon Roelofs
4abf0cd65d [docs] Fix :option: links 2020-04-25 16:19:02 -06:00
Xing GUO
3be88d17d4 [dsymutil][doc] Improve documentation.
This change helps improve `dsymutil` documentation.

- Add missing options
- Re-arrange options in alphabetical order
- Wrap inline options in double-back-quote
- `-v` is for `--version` not `--verbose`

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D78479
2020-04-23 20:06:52 +08:00
Jon Roelofs
7f465f9c3f [docs] Fix :option: links 2020-04-22 14:00:30 -06:00
Jon Roelofs
1174953e01 [docs] Document lit's --timeout=N flag 2020-04-22 12:57:25 -06:00
Richard Smith
be765b5d17 llvm-addr2line: assume addresses on the command line are hexadecimal rather than attempting to guess the base based on the form of the number.
Summary:
This matches the behavior of GNU addr2line. We previously treated
hexadecimal addresses as binary if they started with 0b, otherwise as
octal if they started with 0, otherwise as decimal.

This only affects llvm-addr2line; the behavior of llvm-symbolize is
unaffected.

Reviewers: ikudrin, rupprecht, jhenderson

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73306
2020-04-16 16:16:21 -07:00
Benjamin Kramer
ccaa8e3621 Address sphinx warnings
LanguageExtensions.rst:2191: WARNING: Title underline too short.
llvm-symbolizer.rst:157: Error in "code-block" directive: maximum 1 argument(s) allowed, 30 supplied.
2020-04-13 14:41:55 +02:00
SCOTT-HAMILTON
0cfb8bf071 Typos correction. 2020-04-13 13:46:18 +02:00
Qiu Chaofan
89d4bb7e9b [Docs] Add more FP option description for llc
This patch adds missing description of enable-no-signed-zeros-fp-math
and enable-no-trapping-fp-math options of llc.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D77713
2020-04-09 17:13:01 +08:00
Louis Dionne
9e1de34e9a [lit] Move the recursiveExpansionLimit setting to TestingConfig
The LitConfig is shared across the whole test suite. However, since
enabling recursive expansion can be a breaking change for some test
suites, it's important to confine the setting to test suites that
enable it explicitly.

Note that other issues were raised with the way recursiveExpansionLimit
operates. However, this commit simply moves the setting to the right
place -- the mechanism by which it works can be improved independently.

Differential Revision: https://reviews.llvm.org/D77415
2020-04-06 13:58:00 -04:00
diggerlin
94db89b3ba [llvm-objdump][XCOFF] Use symbol index+symbol name + storage mapping class as label for -D
SUMMARY:

For the llvm-objdump -D, the symbol name is used as a label in the disassembly for the specific address (when a symbol address is equal to the virtual address in the dump).

In XCOFF, multiple symbols may have the same name, being differentiated by their storage mapping class. It is helpful to print the QualName and not just the name when forming the output label for a csect symbol. The symbol index further removes any ambiguity caused by duplicate names.

To maintain compatibility with the binutils objdump, the XCOFF-specific --symbol-description option is added to enable the enhanced format.

Reviewers: hubert.reinterpretcast, James Henderson, Jason Liu ,daltenty
Subscribers: wuzish, nemanjai, hiraditya

Differential Revision: https://reviews.llvm.org/D72973
2020-04-06 10:10:10 -04:00
vgxbj
4e26366ac1 [llvm-objdump] Teach llvm-objdump dump dynamic symbols.
Summary:
This patch is to teach `llvm-objdump` dump dynamic symbols (`-T` and `--dynamic-syms`). Currently, this patch is not fully compatible with `gnu-objdump`, but I would like to continue working on this in next few patches. It has two issues.

1. Some symbols shouldn't be marked as global(g). (`-t/--syms` has same issue as well) (Fixed by D75659)
2. `gnu-objdump` can dump version information and *dynamically* insert before symbol name field.

`objdump -T a.out` gives:

```
DYNAMIC SYMBOL TABLE:
0000000000000000  w   D  *UND*  0000000000000000              _ITM_deregisterTMCloneTable
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 printf
0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 __libc_start_main
0000000000000000  w   D  *UND*  0000000000000000              __gmon_start__
0000000000000000  w   D  *UND*  0000000000000000              _ITM_registerTMCloneTable
0000000000000000  w   DF *UND*  0000000000000000  GLIBC_2.2.5 __cxa_finalize
```

`llvm-objdump -T a.out` gives:

```
DYNAMIC SYMBOL TABLE:
0000000000000000  w   D  *UND*  0000000000000000 _ITM_deregisterTMCloneTable
0000000000000000 g    DF *UND*  0000000000000000 printf
0000000000000000 g    DF *UND*  0000000000000000 __libc_start_main
0000000000000000  w   D  *UND*  0000000000000000 __gmon_start__
0000000000000000  w   D  *UND*  0000000000000000 _ITM_registerTMCloneTable
0000000000000000  w   DF *UND*  0000000000000000 __cxa_finalize
```

Reviewers: jhenderson, grimar, MaskRay, espindola

Reviewed By: jhenderson, grimar

Subscribers: emaste, rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75756
2020-04-05 10:46:59 +08:00
Djordje Todorovic
b4201a6dd9 [llvm-dwarfdump] Add the --show-sections-sizes option
Add an option to llvm-dwarfdump to calculate the bytes within
the debug sections. Dump this numbers when using --statistics
option as well.

This is an initial patch (e.g. we should support other units,
since we only support 'bytes' now).

Differential Revision: https://reviews.llvm.org/D74205
2020-04-02 13:14:30 +02:00
Roman Lebedev
df37c4f17f [llvm-exegesis] 'Min' repetition mode
Summary:
As noted in documentation, different repetition modes have different trade-offs:

> .. option:: -repetition-mode=[duplicate|loop]
>
>  Specify the repetition mode. `duplicate` will create a large, straight line
>  basic block with `num-repetitions` copies of the snippet. `loop` will wrap
>  the snippet in a loop which will be run `num-repetitions` times. The `loop`
>  mode tends to better hide the effects of the CPU frontend on architectures
>  that cache decoded instructions, but consumes a register for counting
>  iterations.

Indeed. Example:

>>! In D74156#1873657, @lebedev.ri wrote:
> At least for `CMOV`, i'm seeing wildly different results
> |           | Latency | RThroughput |
> | duplicate | 1       | 0.8         |
> | loop      | 2       | 0.6         |
> where latency=1 seems correct, and i'd expect the througput to be close to 1/2 (since there are two execution units).

This isn't great for analysis, at least for schedule model development.

As discussed in excruciating detail in

>>! In D74156#1924514, @gchatelet wrote:
>>>! In D74156#1920632, @lebedev.ri wrote:
>> ... did that explanation of the question i'm having made any sense?
>
> Thx for digging in the conversation !
> Ok it makes more sense now.
>
> I discussed it a bit with @courbet:
>  - We want the analysis tool to stay simple so we'd rather not make it knowledgeable of the repetition mode.
>  - We'd like to still be able to select either repetition mode to dig into special cases
>
> So we could add a third `min` repetition mode that would run both and take the minimum. It could be the default option.
> Would you have some time to look what it would take to add this third mode?

there appears to be an agreement that it is indeed sub-par,
and that we should provide an optional, measurement (not analysis!) -time
way to rectify the situation.

However, the solutions isn't entirely straight-forward.

We can just add an actual 'multiplexer' `MinSnippetRepetitor`, because
if we just concatenate snippets produced by `DuplicateSnippetRepetitor`
and `LoopSnippetRepetitor` and run+measure that, the measurement will
naturally be different from what we'd get by running+measuring
them separately and taking the min.
([[ https://www.wolframalpha.com/input/?i=%28x%2By%29%2F2+%21%3D+min%28x%2C+y%29 | `time(D+L)/2 != min(time(D), time(L))` ]])

Also, it seems best to me to have a single snippet instead of generating
a snippet per repetition mode, since the only difference here is that the
loop repetition mode reserves one register for loop counter.

As far as i can tell, we can either teach `BenchmarkRunner::runConfiguration()`
to produce a single report given multiple repetitors (as in the patch),
or do that one layer higher - don't modify `BenchmarkRunner::runConfiguration()`,
produce multiple reports, don't actually print each one, but aggregate them somehow
and only print the final one.

Initially i've gone ahead with the latter approach, but it didn't look like a natural fit;
the former (as in the diff) does seem like a better fit to me.

There's also a question of the test coverage. It sure currently does work here:
```
$ ./bin/llvm-exegesis --opcode-name=CMOV64rr --mode=inverse_throughput --repetition-mode=duplicate
Check generated assembly with: /usr/bin/objdump -d /tmp/snippet-8fb949.o
---
mode:            inverse_throughput
key:
  instructions:
    - 'CMOV64rr RAX RAX R11 i_0x0'
    - 'CMOV64rr RBP RBP R15 i_0x0'
    - 'CMOV64rr RBX RBX RBX i_0x0'
    - 'CMOV64rr RCX RCX RBX i_0x0'
    - 'CMOV64rr RDI RDI R10 i_0x0'
    - 'CMOV64rr RDX RDX RAX i_0x0'
    - 'CMOV64rr RSI RSI RAX i_0x0'
    - 'CMOV64rr R8 R8 R8 i_0x0'
    - 'CMOV64rr R9 R9 RDX i_0x0'
    - 'CMOV64rr R10 R10 RBX i_0x0'
    - 'CMOV64rr R11 R11 R14 i_0x0'
    - 'CMOV64rr R12 R12 R9 i_0x0'
    - 'CMOV64rr R13 R13 R12 i_0x0'
    - 'CMOV64rr R14 R14 R15 i_0x0'
    - 'CMOV64rr R15 R15 R13 i_0x0'
  config:          ''
  register_initial_values:
    - 'RAX=0x0'
    - 'R11=0x0'
    - 'EFLAGS=0x0'
    - 'RBP=0x0'
    - 'R15=0x0'
    - 'RBX=0x0'
    - 'RCX=0x0'
    - 'RDI=0x0'
    - 'R10=0x0'
    - 'RDX=0x0'
    - 'RSI=0x0'
    - 'R8=0x0'
    - 'R9=0x0'
    - 'R14=0x0'
    - 'R12=0x0'
    - 'R13=0x0'
cpu_name:        bdver2
llvm_triple:     x86_64-unknown-linux-gnu
num_repetitions: 10000
measurements:
  - { key: inverse_throughput, value: 0.819, per_snippet_value: 12.285 }
error:           ''
info:            instruction has tied variables, using static renaming.
assembled_snippet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
...
$ ./bin/llvm-exegesis --opcode-name=CMOV64rr --mode=inverse_throughput --repetition-mode=loop
Check generated assembly with: /usr/bin/objdump -d /tmp/snippet-051eb3.o
---
mode:            inverse_throughput
key:
  instructions:
    - 'CMOV64rr RAX RAX R11 i_0x0'
    - 'CMOV64rr RBP RBP RSI i_0x0'
    - 'CMOV64rr RBX RBX R9 i_0x0'
    - 'CMOV64rr RCX RCX RSI i_0x0'
    - 'CMOV64rr RDI RDI RBP i_0x0'
    - 'CMOV64rr RDX RDX R9 i_0x0'
    - 'CMOV64rr RSI RSI RDI i_0x0'
    - 'CMOV64rr R9 R9 R12 i_0x0'
    - 'CMOV64rr R10 R10 R11 i_0x0'
    - 'CMOV64rr R11 R11 R9 i_0x0'
    - 'CMOV64rr R12 R12 RBP i_0x0'
    - 'CMOV64rr R13 R13 RSI i_0x0'
    - 'CMOV64rr R14 R14 R14 i_0x0'
    - 'CMOV64rr R15 R15 R10 i_0x0'
  config:          ''
  register_initial_values:
    - 'RAX=0x0'
    - 'R11=0x0'
    - 'EFLAGS=0x0'
    - 'RBP=0x0'
    - 'RSI=0x0'
    - 'RBX=0x0'
    - 'R9=0x0'
    - 'RCX=0x0'
    - 'RDI=0x0'
    - 'RDX=0x0'
    - 'R12=0x0'
    - 'R10=0x0'
    - 'R13=0x0'
    - 'R14=0x0'
    - 'R15=0x0'
cpu_name:        bdver2
llvm_triple:     x86_64-unknown-linux-gnu
num_repetitions: 10000
measurements:
  - { key: inverse_throughput, value: 0.6083, per_snippet_value: 8.5162 }
error:           ''
info:            instruction has tied variables, using static renaming.
assembled_snippet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
...
$ ./bin/llvm-exegesis --opcode-name=CMOV64rr --mode=inverse_throughput --repetition-mode=min
Check generated assembly with: /usr/bin/objdump -d /tmp/snippet-c7a47d.o
Check generated assembly with: /usr/bin/objdump -d /tmp/snippet-2581f1.o
---
mode:            inverse_throughput
key:
  instructions:
    - 'CMOV64rr RAX RAX R11 i_0x0'
    - 'CMOV64rr RBP RBP R10 i_0x0'
    - 'CMOV64rr RBX RBX R10 i_0x0'
    - 'CMOV64rr RCX RCX RDX i_0x0'
    - 'CMOV64rr RDI RDI RAX i_0x0'
    - 'CMOV64rr RDX RDX R9 i_0x0'
    - 'CMOV64rr RSI RSI RAX i_0x0'
    - 'CMOV64rr R9 R9 RBX i_0x0'
    - 'CMOV64rr R10 R10 R12 i_0x0'
    - 'CMOV64rr R11 R11 RDI i_0x0'
    - 'CMOV64rr R12 R12 RDI i_0x0'
    - 'CMOV64rr R13 R13 RDI i_0x0'
    - 'CMOV64rr R14 R14 R9 i_0x0'
    - 'CMOV64rr R15 R15 RBP i_0x0'
  config:          ''
  register_initial_values:
    - 'RAX=0x0'
    - 'R11=0x0'
    - 'EFLAGS=0x0'
    - 'RBP=0x0'
    - 'R10=0x0'
    - 'RBX=0x0'
    - 'RCX=0x0'
    - 'RDX=0x0'
    - 'RDI=0x0'
    - 'R9=0x0'
    - 'RSI=0x0'
    - 'R12=0x0'
    - 'R13=0x0'
    - 'R14=0x0'
    - 'R15=0x0'
cpu_name:        bdver2
llvm_triple:     x86_64-unknown-linux-gnu
num_repetitions: 10000
measurements:
  - { key: inverse_throughput, value: 0.6073, per_snippet_value: 8.5022 }
error:           ''
info:            instruction has tied variables, using static renaming.
assembled_snippet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
...
```
but i open to suggestions as to how test that.

I also have gone with the suggestion to default to this new mode.
This was irking me for some time, so i'm happy to finally see progress here.
Looking forward to feedback.

Reviewers: courbet, gchatelet

Reviewed By: courbet, gchatelet

Subscribers: mstojanovic, RKSimon, llvm-commits, courbet, gchatelet

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D76921
2020-04-02 09:28:35 +03:00