[ntuple] Add support for half-precision floats #13844

enirolf · 2023-10-11T17:08:18Z

This PR adds support to 16-bit (IEEE 754-2008) floating point numbers to RNTuple. In similar vein to 32-bit doubles, this is enabled by changing the column representation of ordinary float fields (i.e., regular float fields are used, but the values are saved to disk using half precision).

Because half-precision floats are only part of the C++ standard from C++23 onwards, for now we use parts of the half library (MIT-licensed) for converting between half- and single-precision floats. For x86 processors, the F16C ISA extension can be enabled to do this conversion on the hardware directly. However, this appears to mess with TFormulaTests.

phsft-bot · 2023-10-11T17:08:27Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac11/noimt, mac12arm/cxx20, windows10/default
How to customize builds

phsft-bot · 2023-10-11T17:09:59Z

Build failed on ROOT-ubuntu2004/python3.
See console output.

phsft-bot · 2023-10-11T17:32:14Z

Build failed on ROOT-ubuntu2204/nortcxxmod.
Running on root-ubuntu-2204-3.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Errors:

[2023-10-11T17:31:20.272Z] /home/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:174:4: error: ‘_Float16’ was not declared in this scope; did you mean ‘_Float64’?
[2023-10-11T17:31:20.272Z] /home/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:176:7: error: ‘fp16Val’ was not declared in this scope
[2023-10-11T17:31:20.272Z] /home/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:176:29: error: ‘_Float16’ does not name a type; did you mean ‘_Float64’?
[2023-10-11T17:31:20.272Z] /home/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:187:4: error: ‘_Float16’ was not declared in this scope; did you mean ‘_Float64’?
[2023-10-11T17:31:20.272Z] /home/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:189:20: error: ‘fp16Val’ was not declared in this scope

phsft-bot · 2023-10-11T18:26:20Z

Build failed on ROOT-performance-centos8-multicore/soversion.
Running on olbdw-01.cern.ch:/data/sftnight/workspace/root-pullrequests-build
See console output.

Errors:

[2023-10-11T18:25:34.265Z] /data/sftnight/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:174:4: error: ‘_Float16’ was not declared in this scope
[2023-10-11T18:25:34.265Z] /data/sftnight/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:176:7: error: ‘fp16Val’ was not declared in this scope
[2023-10-11T18:25:34.520Z] /data/sftnight/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:176:29: error: ‘_Float16’ does not name a type; did you mean ‘_Float64’?
[2023-10-11T18:25:34.520Z] /data/sftnight/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:187:4: error: ‘_Float16’ was not declared in this scope
[2023-10-11T18:25:34.520Z] /data/sftnight/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:189:20: error: ‘fp16Val’ was not declared in this scope

phsft-bot · 2023-10-11T18:28:11Z

Build failed on windows10/default.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Errors:

[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(174,4): error C2065: '_Float16': undeclared identifier [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(174,13): error C2146: syntax error: missing ';' before identifier 'fp16Val' [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(174,13): error C2065: 'fp16Val': undeclared identifier [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(176,7): error C2065: 'fp16Val': undeclared identifier [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(176,29): error C2061: syntax error: identifier '_Float16' [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(177,39): error C2065: 'fp16Val': undeclared identifier [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(187,4): error C2065: '_Float16': undeclared identifier [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(187,13): error C2146: syntax error: missing ';' before identifier 'fp16Val' [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(187,13): error C2065: 'fp16Val': undeclared identifier [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]
[2023-10-11T18:08:29.273Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(189,20): error C2065: 'fp16Val': undeclared identifier [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]

And 1 more

github-actions · 2023-10-11T18:31:21Z

Test Results

      11 files       11 suites 1d 18h 13m 31s ⏱️
  2 481 tests   2 481 ✔️ 0 💤 0 ❌
26 220 runs 26 220 ✔️ 0 💤 0 ❌

Results for commit fefd73a.

♻️ This comment has been updated with latest results.

phsft-bot · 2023-10-12T19:11:38Z

Build failed on mac11/noimt.
See console output.

phsft-bot · 2023-10-16T16:20:08Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

phsft-bot · 2023-10-16T16:32:39Z

Build failed on ROOT-performance-centos8-multicore/soversion.
Running on olbdw-01.cern.ch:/data/sftnight/workspace/root-pullrequests-build
See console output.

Errors:

[2023-10-16T16:32:07.166Z] /data/sftnight/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:17:10: fatal error: ROOT/Float16.hxx: No such file or directory

phsft-bot · 2023-10-16T16:34:41Z

Build failed on mac12arm/cxx20.
Running on macphsft26.dyndns.cern.ch:/Users/sftnight/build/workspace/root-pullrequests-build
See console output.

Errors:

[2023-10-16T16:34:37.880Z] FAILED: tree/ntuple/CMakeFiles/ROOTNTuple.dir/v7/src/RColumnElement.cxx.o
[2023-10-16T16:34:38.139Z] /Users/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:17:10: fatal error: 'ROOT/Float16.hxx' file not found

phsft-bot · 2023-10-16T16:44:42Z

Build failed on ROOT-ubuntu2004/python3.
Running on root-ubuntu-2004-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Errors:

[2023-10-16T16:44:02.467Z] FAILED: tree/ntuple/CMakeFiles/ROOTNTuple.dir/v7/src/RColumnElement.cxx.o
[2023-10-16T16:44:02.777Z] /home/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:17:10: fatal error: ROOT/Float16.hxx: No such file or directory

phsft-bot · 2023-10-16T16:49:55Z

Build failed on ROOT-ubuntu2204/nortcxxmod.
Running on root-ubuntu-2204-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Errors:

[2023-10-16T16:48:46.748Z] /home/sftnight/build/workspace/root-pullrequests-build/root/tree/ntuple/v7/src/RColumnElement.cxx:17:10: fatal error: ROOT/Float16.hxx: No such file or directory

phsft-bot · 2023-10-16T17:21:42Z

Build failed on windows10/default.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Errors:

[2023-10-16T17:02:59.290Z] C:\build\workspace\root-pullrequests-build\root\tree\ntuple\v7\src\RColumnElement.cxx(17,10): fatal error C1083: Cannot open include file: 'ROOT/Float16.hxx': No such file or directory [C:\build\workspace\root-pullrequests-build\build\tree\ntuple\ROOTNTuple.vcxproj]

phsft-bot · 2023-10-17T06:51:23Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

phsft-bot · 2023-10-17T07:30:20Z

Build failed on windows10/default.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Errors:

[2023-10-17T07:27:44.010Z] C:\build\workspace\root-pullrequests-build\root\core\imt\src\TTaskGroup.cxx(18,10): fatal error C1083: Cannot open include file: 'tbb/task_group.h': No such file or directory [C:\build\workspace\root-pullrequests-build\build\core\imt\Imt.vcxproj]
[2023-10-17T07:27:44.285Z] C:\build\workspace\root-pullrequests-build\root\core\imt\src\ROpaqueTaskArena.hxx(1,10): fatal error C1083: Cannot open include file: 'tbb/task_arena.h': No such file or directory [C:\build\workspace\root-pullrequests-build\build\core\imt\Imt.vcxproj]
[2023-10-17T07:27:45.429Z] C:\build\workspace\root-pullrequests-build\root\core\imt\src\ROpaqueTaskArena.hxx(1,10): fatal error C1083: Cannot open include file: 'tbb/task_arena.h': No such file or directory [C:\build\workspace\root-pullrequests-build\build\core\imt\Imt.vcxproj]

phsft-bot · 2023-10-17T07:42:10Z

Build failed on ROOT-ubuntu2204/nortcxxmod.
Running on root-ubuntu-2204-2.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

projectroot.test.test_TFormulaTests

phsft-bot · 2023-10-17T08:35:48Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

phsft-bot · 2023-10-17T09:12:45Z

Build failed on windows10/default.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Errors:

[2023-10-17T09:10:02.720Z] C:\build\workspace\root-pullrequests-build\root\core\imt\src\TTaskGroup.cxx(18,10): fatal error C1083: Cannot open include file: 'tbb/task_group.h': No such file or directory [C:\build\workspace\root-pullrequests-build\build\core\imt\Imt.vcxproj]
[2023-10-17T09:10:03.001Z] C:\build\workspace\root-pullrequests-build\root\core\imt\src\ROpaqueTaskArena.hxx(1,10): fatal error C1083: Cannot open include file: 'tbb/task_arena.h': No such file or directory [C:\build\workspace\root-pullrequests-build\build\core\imt\Imt.vcxproj]
[2023-10-17T09:10:04.178Z] C:\build\workspace\root-pullrequests-build\root\core\imt\src\ROpaqueTaskArena.hxx(1,10): fatal error C1083: Cannot open include file: 'tbb/task_arena.h': No such file or directory [C:\build\workspace\root-pullrequests-build\build\core\imt\Imt.vcxproj]

phsft-bot · 2023-10-17T09:23:09Z

Build failed on ROOT-ubuntu2204/nortcxxmod.
Running on root-ubuntu-2204-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

projectroot.test.test_TFormulaTests

phsft-bot · 2023-10-17T10:45:53Z

Build failed on ROOT-ubuntu2004/python3.
Running on root-ubuntu-2004-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

projectroot.test.test_TFormulaTests

phsft-bot · 2023-10-17T13:17:29Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

phsft-bot · 2023-10-17T14:38:43Z

Build failed on windows10/default.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Failing tests:

jblomer

Cool! I think it's very good shape.

Let's also add the new column type to the Packing.OnDiskEncoding unit test.

core/base/v7/inc/ROOT/RFloat16.hxx

jblomer · 2023-10-18T11:30:48Z

core/base/v7/inc/ROOT/RFloat16.hxx

+#define HALF_ENABLE_F16C_INTRINSICS __F16C__
+#endif
+#if HALF_ENABLE_F16C_INTRINSICS
+#include <immintrin.h>


Just curious, does this actually enable intrinsics on a "standard platform"?

Not by default. ROOT would have to be compiled with -mf16c, but this doesn't seem to play nice with projectroot.test.test_TFormulaTests when added to the CMake configuration. It might be worth it to further investigate and come up with a solution, though.

tree/ntuple/v7/src/RColumnElement.cxx

tree/ntuple/v7/src/RField.cxx

tree/ntuple/v7/test/ntuple_types.cxx

jblomer · 2023-10-18T11:48:37Z

tree/ntuple/v7/test/ntuple_types.cxx

+   FileRaii fileGuard("test_ntuple_float16.root");
+
+   auto f1Fld = RFieldBase::Create("f1", "float").Unwrap();
+   f1Fld->SetColumnRepresentative({ROOT::Experimental::EColumnType::kReal16});


Suggested change

f1Fld->SetColumnRepresentative({ROOT::Experimental::EColumnType::kReal16});

f1Fld->SetHalfPrecision();

tree/ntuple/v7/test/ntuple_types.cxx

phsft-bot · 2023-10-26T15:37:28Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

phsft-bot · 2023-11-03T12:54:37Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

phsft-bot · 2023-11-03T13:48:52Z

Build failed on ROOT-ubuntu2004/python3.
Running on root-ubuntu-2004-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

projectroot.tmva.pymva.test.PyMVA_Keras_Regression

jblomer

Great! Let's add one more test to the Packing, OnDiskEncoding unit test in ntuple_packing to verify the on-disk bit pattern is as expected.

jblomer · 2023-11-09T21:24:53Z

tree/ntuple/v7/inc/ROOT/RColumnElement.hxx

+         floatArray[i] = Internal::HalfToFloat(uint16Array[i]);
+         ByteSwapIfNecessary(floatArray[i]);


Shouldn't these two lines be reversed (in reverse order to packing)?

Yes, you're completely right!

phsft-bot · 2023-11-10T16:20:21Z

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

enirolf self-assigned this Oct 11, 2023

enirolf force-pushed the ntuple-float16 branch from a3011fe to d5a668d Compare October 16, 2023 16:20

enirolf force-pushed the ntuple-float16 branch from d5a668d to c08b11a Compare October 17, 2023 06:51

enirolf force-pushed the ntuple-float16 branch from c08b11a to 047aded Compare October 17, 2023 08:35

enirolf force-pushed the ntuple-float16 branch from 047aded to d11e9df Compare October 17, 2023 13:17

enirolf marked this pull request as ready for review October 18, 2023 06:36

enirolf requested review from bellenot and jblomer as code owners October 18, 2023 06:36

enirolf requested review from Axel-Naumann and pcanal as code owners October 18, 2023 06:36

enirolf requested a review from vepadulano October 18, 2023 06:36

jblomer requested changes Oct 18, 2023

View reviewed changes

enirolf mentioned this pull request Oct 23, 2023

Add half-precision floats to RtypesCores.h #13917

Closed

[v7] Add conversion to and from half-precision floats

6105ef3

enirolf force-pushed the ntuple-float16 branch from d11e9df to 0ed771b Compare October 26, 2023 15:37

enirolf requested a review from jblomer October 27, 2023 09:35

enirolf force-pushed the ntuple-float16 branch from 0ed771b to d924406 Compare November 3, 2023 12:54

guitargeek added the in:RNTuple label Nov 5, 2023

jblomer requested changes Nov 9, 2023

View reviewed changes

enirolf added 2 commits November 10, 2023 16:37

[ntuple] Add support for half-precision floats

3144849

[ntuple] Add packing tests for half-precision floats

fefd73a

enirolf force-pushed the ntuple-float16 branch from d924406 to fefd73a Compare November 10, 2023 16:20

jblomer approved these changes Nov 12, 2023

View reviewed changes

jblomer merged commit 21290a4 into root-project:master Nov 12, 2023

enirolf deleted the ntuple-float16 branch November 29, 2023 12:45

	f1Fld->SetColumnRepresentative({ROOT::Experimental::EColumnType::kReal16});
	f1Fld->SetHalfPrecision();

		floatArray[i] = Internal::HalfToFloat(uint16Array[i]);
		ByteSwapIfNecessary(floatArray[i]);

[ntuple] Add support for half-precision floats #13844

[ntuple] Add support for half-precision floats #13844

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