[BOLT][merge-fdata] Fix basic sample profile aggregation without LBR info #118481
Conversation
tdusnoki
requested review from
aaupov,
maksfb,
rafaelauler,
ayermolo and
dcci
as code owners
|
Thank you for submitting a Pull Request (PR) to the LLVM Project! This PR will be automatically labeled and the relevant teams will be notified. If you wish to, you can add reviewers by using the "Reviewers" section on this page. If this is not working for you, it is probably because you do not have write permissions for the repository. In which case you can instead tag reviewers by name in a comment by using If you have received no comments on your PR for a week, you can request a review by "ping"ing the PR by adding a comment “Ping”. The common courtesy "ping" rate is once a week. Please remember that you are asking for valuable time from other developers. If you have further questions, they may be answered by the LLVM GitHub User Guide. You can also ask questions in a comment on this PR, on the LLVM Discord or on the forums. |
|
@llvm/pr-subscribers-bolt Author: Tibor Dusnoki (tdusnoki) ChangesWhen a basic sample profile is gathered without LBR info, the generated profile contains a "no-lbr" tag in the first line of the fdata file. This PR fixes merge-fdata to recognize and save this tag to the output file. Full diff: https://github.com/llvm/llvm-project/pull/118481.diff 5 Files Affected:
diff --git a/bolt/test/X86/Inputs/no-lbr_profile_1.fdata b/bolt/test/X86/Inputs/no-lbr_profile_1.fdata
new file mode 100644
index 00000000000000..34035b12c5bf0f
--- /dev/null
+++ b/bolt/test/X86/Inputs/no-lbr_profile_1.fdata
@@ -0,0 +1,305 @@
+no_lbr cycles:HG:
+1 __aarch64_cas4_acq/1 c 2
+1 __aarch64_cas4_acq/1 0 20
+1 __aarch64_cas4_acq/1 14 954
+1 __aarch64_swp4_rel/1 14 657
+1 __ieee754_fmod 54 1
+1 __ieee754_fmod 14 1
+1 __ieee754_fmod c8 59
+1 __ieee754_fmod 74 2
+1 __ieee754_fmod 8c 119
+1 __ieee754_fmod b4 55
+1 __ieee754_fmod 78 95
+1 __ieee754_fmod a0 93
+1 __ieee754_fmod 94 33
+1 __ieee754_fmod c4 96
+1 __ieee754_fmod 84 31
+1 __ieee754_fmod 80 9
+1 __ieee754_fmod c0 38
+1 __ieee754_fmod 1c 12
+1 __ieee754_fmod 88 111
+1 __ieee754_fmod 18 14
+1 __ieee754_fmod 98 95
+1 __ieee754_fmod ac 13
+1 __ieee754_fmod 58 7
+1 __ieee754_fmod 3c 14
+1 __ieee754_fmod b0 39
+1 __ieee754_fmod 7c 32
+1 __ieee754_fmod 20 1
+1 __ieee754_fmod 5c 16
+1 __ieee754_fmod bc 3
+1 __ieee754_fmod 90 127
+1 __ieee754_fmod 8 2
+1 __ieee754_fmod e0 2
+1 __ieee754_fmod 28 1
+1 __ieee754_fmod 38 5
+1 __ieee754_fmod 68 2
+1 __random/1 34 14
+1 __random/1 18 19
+1 __random/1 14 17
+1 __random/1 84 49
+1 __random/1 c 1
+1 __random/1 64 85
+1 __random/1 3c 60
+1 __random/1 78 7
+1 __random/1 58 33
+1 __random/1 2c 2
+1 __random_r/1 58 1
+1 __random_r/1 2c 31
+1 __random_r/1 c 39
+1 __random_r/1 48 38
+1 cos 300 1
+1 cos 438 1
+1 cos 32c 3
+1 cos 370 3
+1 cos 5bc 15
+1 cos 14c 2
+1 cos 414 5
+1 cos 324 1
+1 cos 2bc 28
+1 cos 44c 6
+1 cos 48 1
+1 cos 238 17
+1 cos 38 18
+1 cos 50 2
+1 cos 440 49
+1 cos 30c 5
+1 cos 46c 7
+1 cos 68 3
+1 cos 5c0 11
+1 cos 2c4 40
+1 cos 18 17
+1 cos 3d8 39
+1 cos 5c4 12
+1 cos 350 6
+1 cos 5b8 59
+1 cos 6c 4
+1 cos 2ec 16
+1 cos 64 25
+1 cos 468 2
+1 cos 70 90
+1 cos 248 17
+1 cos 2d8 12
+1 cos 26c 1
+1 cos 344 5
+1 cos 2c0 45
+1 cos 58 7
+1 cos 328 4
+1 cos 308 7
+1 cos 40c 10
+1 cos 3f8 27
+1 cos 5d0 9
+1 cos 3e0 55
+1 cos 3e4 16
+1 cos 274 5
+1 cos 2cc 70
+1 cos 264 3
+1 cos 28c 6
+1 cos 5e8 4
+1 cos 444 7
+1 cos 4c 3
+1 cos 3dc 52
+1 cos 304 1
+1 cos 288 16
+1 cos 608 2
+1 cos 6e0 14
+1 cos 2a8 14
+1 cos 2d4 7
+1 cos 340 32
+1 cos 5dc 2
+1 cos 138 18
+1 cos 268 11
+1 cos 2e8 3
+1 cos 3f4 2
+1 cos 400 1
+1 cos 2b4 4
+1 cos 294 2
+1 cos 420 4
+1 cos 2e4 1
+1 cos 418 2
+1 cos 36c 1
+1 exp 54 2
+1 exp 3c 1
+1 exp 70 10
+1 exp 50 228
+1 exp 48 1
+1 exp 14 164
+1 exp 34 12
+1 exp 0 20
+1 exp 74 4
+1 fmod 8 11
+1 fmod 28 19
+1 fmod 14 3
+1 fmod 4 11
+1 fmod 24 9
+1 fmod 0 2
+1 fmod 20 1
+1 log a8 2
+1 log 94 12
+1 log 20 78
+1 log b4 14
+1 log 68 79
+1 log 10 5
+1 log 30 25
+1 log 0 10
+1 log 50 14
+1 log 88 6
+1 log 74 18
+1 main 1c8 1
+1 main 70 1
+1 main e0 1
+1 main 48 3
+1 main 110 3
+1 main 12c 19
+1 main cc 21
+1 main d8 15
+1 main 44 9
+1 main d4 5
+1 main 114 2
+1 main 7c 18
+1 main fc 160
+1 main f8 27
+1 main 11c 21
+1 main bc 9
+1 main b8 26
+1 main a4 4
+1 main 94 15
+1 main 60 19
+1 main b0 2
+1 rand 10 1
+1 rand 4 14
+1 rand 8 13
+1 sin 2a0 1
+1 sin 25c 1
+1 sin 260 1
+1 sin a0 1
+1 sin 608 1
+1 sin 1c4 1
+1 sin 74 2
+1 sin 4a8 2
+1 sin 228 1
+1 sin 4b8 27
+1 sin 45c 1
+1 sin 58 6
+1 sin 274 21
+1 sin 220 15
+1 sin 0 9
+1 sin 628 1
+1 sin 284 6
+1 sin 2a8 3
+1 sin 208 9
+1 sin 4bc 4
+1 sin 700 7
+1 sin 4ac 6
+1 sin 70 29
+1 sin 280 2
+1 sin 4e8 1
+1 sin 240 1
+1 sin 5f0 6
+1 sin 5e4 16
+1 sin 290 1
+1 sin 204 3
+1 sin 270 2
+1 sin 4c8 3
+1 sin 458 5
+1 sin 60 4
+1 sin 1c 17
+1 sin 170 17
+1 sin 5e0 2
+1 sin 464 1
+1 sin 4d0 2
+1 sin 234 8
+1 sin 484 1
+1 sin 4e4 5
+1 sin 4c4 9
+1 sin 468 1
+1 sin 64 13
+1 sin 20c 4
+1 sin 200 10
+1 sin 184 1
+1 sin 1f0 10
+1 sin 5dc 6
+1 sin 1a4 2
+1 sin 1d0 17
+1 sin 23c 4
+1 sin 48c 7
+1 sin 3c 17
+1 sin 488 3
+1 sin 164 5
+1 sin 30 1
+1 sin 1e4 5
+1 sin 1b0 16
+1 sin 450 4
+1 sin 190 23
+1 sin 470 19
+1 sin 230 1
+1 sin 4b0 3
+1 sin 10 4
+1 sin 78 3
+1 sin 5c 5
+1 sin 278 6
+1 sin 248 2
+1 sin 238 2
+1 sin 5fc 2
+1 sin 490 1
+1 sin 268 3
+1 sin 2a4 4
+1 sin 498 1
+1 sqrt 1c 66
+1 tan 374 1
+1 tan 254 1
+1 tan 344 1
+1 tan 230 1
+1 tan 1e0 1
+1 tan 1c4 1
+1 tan 510 1
+1 tan 5c4 2
+1 tan 2b8 1
+1 tan 140 2
+1 tan 6c 1
+1 tan c 16
+1 tan 64 36
+1 tan 3b4 12
+1 tan 2c 16
+1 tan 2ac 16
+1 tan 5f8 24
+1 tan 358 32
+1 tan 4c 19
+1 tan 8c 22
+1 tan 134 1
+1 tan 26c 3
+1 tan 124 20
+1 tan 5bc 4
+1 tan 234 1
+1 tan 78 25
+1 tan 1c0 6
+1 tan 250 1
+1 tan 560 2
+1 tan 30c 13
+1 tan 390 157
+1 tan 378 20
+1 tan 33c 2
+1 tan 51c 319
+1 tan 2ec 22
+1 tan 5a8 8
+1 tan 98 22
+1 tan 144 18
+1 tan 548 9
+1 tan 128 16
+1 tan 130 3
+1 tan 5b8 3
+1 tan 394 25
+1 tan 340 6
+1 tan 148 7
+1 tan 1d8 2
+1 tan 2cc 25
+1 tan 4f0 1
+1 tan 18 1
+1 tan 5c0 5
+1 tan 544 2
+1 tan 540 6
+1 tan 550 3
+1 tan 214 5
+1 tan 338 2
+1 tan 354 3
+1 tan 53c 8
diff --git a/bolt/test/X86/Inputs/no-lbr_profile_2.fdata b/bolt/test/X86/Inputs/no-lbr_profile_2.fdata
new file mode 100644
index 00000000000000..f057d7a5021034
--- /dev/null
+++ b/bolt/test/X86/Inputs/no-lbr_profile_2.fdata
@@ -0,0 +1,290 @@
+no_lbr cycles:HG:
+1 __aarch64_cas4_acq/1 14 981
+1 __aarch64_cas4_acq/1 0 23
+1 __aarch64_swp4_rel/1 c 2
+1 __aarch64_swp4_rel/1 14 663
+1 __ieee754_fmod 80 17
+1 __ieee754_fmod bc 4
+1 __ieee754_fmod b4 56
+1 __ieee754_fmod 58 12
+1 __ieee754_fmod b0 49
+1 __ieee754_fmod c0 44
+1 __ieee754_fmod 18 12
+1 __ieee754_fmod 88 98
+1 __ieee754_fmod 38 12
+1 __ieee754_fmod c4 73
+1 __ieee754_fmod 1c 11
+1 __ieee754_fmod 98 85
+1 __ieee754_fmod a0 85
+1 __ieee754_fmod c8 65
+1 __ieee754_fmod ac 15
+1 __ieee754_fmod 8c 113
+1 __ieee754_fmod 8 1
+1 __ieee754_fmod 84 35
+1 __ieee754_fmod 78 103
+1 __ieee754_fmod 5c 8
+1 __ieee754_fmod 3c 8
+1 __ieee754_fmod 68 1
+1 __ieee754_fmod e0 4
+1 __ieee754_fmod 7c 38
+1 __ieee754_fmod 14 1
+1 __ieee754_fmod 90 119
+1 __ieee754_fmod 94 27
+1 __random/1 30 1
+1 __random/1 2c 1
+1 __random/1 14 17
+1 __random/1 c 1
+1 __random/1 84 45
+1 __random/1 78 5
+1 __random/1 64 80
+1 __random/1 58 35
+1 __random/1 34 18
+1 __random/1 3c 61
+1 __random/1 18 25
+1 __random_r/1 58 3
+1 __random_r/1 c 39
+1 __random_r/1 2c 35
+1 __random_r/1 48 41
+1 cos 448 1
+1 cos 3f4 2
+1 cos 2ac 3
+1 cos 2c8 1
+1 cos 32c 2
+1 cos 2cc 66
+1 cos 3d8 42
+1 cos 2bc 29
+1 cos 138 15
+1 cos 414 7
+1 cos 344 6
+1 cos 370 10
+1 cos 4c 12
+1 cos 2e4 2
+1 cos 350 4
+1 cos 38 13
+1 cos 248 15
+1 cos 264 5
+1 cos 5b8 52
+1 cos 64 18
+1 cos 328 3
+1 cos 3dc 44
+1 cos 50 6
+1 cos 184 1
+1 cos 58 7
+1 cos 2ec 21
+1 cos 300 5
+1 cos 70 88
+1 cos 2d8 13
+1 cos 6dc 3
+1 cos 6e0 11
+1 cos 27c 2
+1 cos 2c0 50
+1 cos 3e0 41
+1 cos 68 1
+1 cos 46c 8
+1 cos 2d4 5
+1 cos 340 24
+1 cos 3f8 29
+1 cos 2a8 21
+1 cos 48 3
+1 cos 44c 2
+1 cos 440 51
+1 cos 2c4 41
+1 cos 238 16
+1 cos 5d0 11
+1 cos 3e4 19
+1 cos 324 2
+1 cos 2b8 1
+1 cos 18 18
+1 cos 5bc 18
+1 cos 5c4 13
+1 cos 6c 4
+1 cos 274 1
+1 cos 268 18
+1 cos 54 5
+1 cos 294 3
+1 cos 288 5
+1 cos 420 7
+1 cos 26c 4
+1 cos 308 10
+1 cos 314 1
+1 cos 5c0 18
+1 cos 444 9
+1 cos 2b4 2
+1 cos 5e8 2
+1 cos 28c 1
+1 cos 40c 7
+1 cos 84 1
+1 cos 418 2
+1 cos 304 1
+1 cos 5dc 3
+1 exp 2c 1
+1 exp 24 2
+1 exp 54 3
+1 exp 50 201
+1 exp 34 26
+1 exp 14 140
+1 exp 4c 1
+1 exp 70 14
+1 exp 0 14
+1 exp 10 1
+1 exp 74 1
+1 fmod 18 4
+1 fmod 24 12
+1 fmod 28 33
+1 fmod 4 17
+1 fmod 8 13
+1 fmod 20 1
+1 fmod 14 1
+1 log 68 72
+1 log 94 12
+1 log 74 18
+1 log a8 5
+1 log 50 15
+1 log b4 10
+1 log 0 12
+1 log 20 72
+1 log 30 28
+1 log 88 6
+1 main 44 16
+1 main bc 12
+1 main cc 22
+1 main 12c 12
+1 main 70 1
+1 main f8 18
+1 main 48 3
+1 main 114 3
+1 main e0 4
+1 main fc 143
+1 main 60 22
+1 main d8 6
+1 main d0 1
+1 main b8 25
+1 main dc 1
+1 main 94 20
+1 main 11c 16
+1 main 110 1
+1 main b0 4
+1 main 7c 13
+1 main 130 4
+1 main a4 1
+1 rand 4 24
+1 rand 8 13
+1 rand 10 3
+1 rand 0 1
+1 sin 4a8 1
+1 sin 260 1
+1 sin 490 1
+1 sin 2a0 3
+1 sin 2a8 1
+1 sin 1c4 3
+1 sin 228 1
+1 sin 248 1
+1 sin 234 6
+1 sin 628 1
+1 sin 700 6
+1 sin 0 25
+1 sin 1c 13
+1 sin 2a4 5
+1 sin 4d0 1
+1 sin 290 1
+1 sin 3c 18
+1 sin 208 4
+1 sin 1f0 10
+1 sin 268 2
+1 sin 5e4 18
+1 sin 25c 1
+1 sin 60 2
+1 sin 5dc 1
+1 sin 274 24
+1 sin 1e4 2
+1 sin 450 6
+1 sin 1d0 24
+1 sin 23c 4
+1 sin 258 3
+1 sin 64 12
+1 sin 468 5
+1 sin 1a4 3
+1 sin 78 6
+1 sin 220 14
+1 sin 4b8 20
+1 sin 458 5
+1 sin 470 20
+1 sin 170 13
+1 sin 164 4
+1 sin 5f0 7
+1 sin 484 8
+1 sin 4b0 2
+1 sin 190 27
+1 sin 184 3
+1 sin 4c4 3
+1 sin 70 14
+1 sin 284 3
+1 sin 58 9
+1 sin 288 1
+1 sin 10 4
+1 sin 210 5
+1 sin 278 6
+1 sin 4bc 4
+1 sin 4ac 2
+1 sin 608 2
+1 sin 498 2
+1 sin 1b0 23
+1 sin 4e4 3
+1 sin 280 1
+1 sin 20c 12
+1 sin 45c 7
+1 sin 48c 5
+1 sin 218 2
+1 sin 5c 5
+1 sin 200 5
+1 sqrt 1c 62
+1 tan 550 1
+1 tan 588 2
+1 tan 120 1
+1 tan 33c 2
+1 tan 5c4 2
+1 tan 540 4
+1 tan 214 2
+1 tan 8c 30
+1 tan 374 4
+1 tan c 15
+1 tan 2ec 17
+1 tan 408 1
+1 tan 64 49
+1 tan 2cc 17
+1 tan 26c 4
+1 tan 140 2
+1 tan 548 6
+1 tan 144 14
+1 tan 358 31
+1 tan 340 4
+1 tan 78 28
+1 tan 148 7
+1 tan 560 2
+1 tan 128 16
+1 tan 270 1
+1 tan 5bc 1
+1 tan 394 27
+1 tan 30c 19
+1 tan 378 20
+1 tan 2ac 26
+1 tan 3b4 17
+1 tan 5b8 1
+1 tan 51c 353
+1 tan 35c 2
+1 tan 98 22
+1 tan 5f8 22
+1 tan 2c 18
+1 tan 5a8 6
+1 tan 5c0 4
+1 tan 124 14
+1 tan 1e8 1
+1 tan 4c 21
+1 tan 1c4 6
+1 tan 510 2
+1 tan 1c0 4
+1 tan 338 1
+1 tan 390 169
+1 tan 6c 2
+1 tan 3b0 3
+1 tan 53c 10
diff --git a/bolt/test/X86/merge-fdata-lbr-mode.test b/bolt/test/X86/merge-fdata-lbr-mode.test
new file mode 100644
index 00000000000000..d32c9caec90e6a
--- /dev/null
+++ b/bolt/test/X86/merge-fdata-lbr-mode.test
@@ -0,0 +1,6 @@
+## Check that merge-fdata tool doesn't falsely print no_lbr when not in no-lbr mode
+
+RUN: merge-fdata %S/Inputs/blarge.fdata %S/Inputs/blarge.fdata \
+RUN: | FileCheck %s --check-prefix=CHECK-FDATA
+
+CHECK-FDATA-NOT: no_lbr
diff --git a/bolt/test/X86/merge-fdata-no-lbr-mode.test b/bolt/test/X86/merge-fdata-no-lbr-mode.test
new file mode 100644
index 00000000000000..d63f98e096927d
--- /dev/null
+++ b/bolt/test/X86/merge-fdata-no-lbr-mode.test
@@ -0,0 +1,8 @@
+## Check that merge-fdata tool correctly processes fdata files with header
+## string produced by no-lbr mode (no_lbr)
+RUN: merge-fdata %S/Inputs/no-lbr_profile_1.fdata \
+RUN: %S/Inputs/no-lbr_profile_2.fdata \
+RUN: | FileCheck %s --check-prefix=CHECK-FDATA
+
+CHECK-FDATA: no_lbr
+CHECK-FDATA: 1 tan 234 1
diff --git a/bolt/tools/merge-fdata/merge-fdata.cpp b/bolt/tools/merge-fdata/merge-fdata.cpp
index 89ca46c1c0a8fa..4b7428020851ec 100644
--- a/bolt/tools/merge-fdata/merge-fdata.cpp
+++ b/bolt/tools/merge-fdata/merge-fdata.cpp
@@ -265,6 +265,7 @@ bool isYAML(const StringRef Filename) {
void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
errs() << "Using legacy profile format.\n";
std::optional<bool> BoltedCollection;
+ std::optional<bool> NoLBR;
std::mutex BoltedCollectionMutex;
typedef StringMap<uint64_t> ProfileTy;
@@ -304,6 +305,10 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
SmallVector<StringRef> Lines;
SplitString(Buf, Lines, "\n");
for (StringRef Line : Lines) {
+ if (Line.contains("no_lbr")) {
+ NoLBR = true;
+ continue;
+ }
size_t Pos = Line.rfind(" ");
if (Pos == StringRef::npos)
report_error(Filename, "Malformed / corrupted profile");
@@ -336,6 +341,8 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
if (BoltedCollection.value_or(false))
output() << "boltedcollection\n";
+ if (NoLBR.value_or(true))
+ output() << "no_lbr\n";
for (const auto &[Key, Value] : MergedProfile)
output() << Key << " " << Value << "\n";
|
tdusnoki
force-pushed
the
fix-nolbr-merge
branch
3 times, most recently
from
ade292b to
c0356a5
Compare
| @@ -297,6 +298,25 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) { | |||
| "cannot mix profile collected in BOLT and non-BOLT deployments"); | |||
| BoltedCollection = false; | |||
| } | |||
| // Check if the string "no_lbr" is in the first line | |||
| size_t FirstNewline = Buf.find('\n'); | |||
There was a problem hiding this comment.
Can it be on a second line, in case of boltedcollection?
There was a problem hiding this comment.
If it is, we've already dropped the first line just above when checking for boltedcollection.
There was a problem hiding this comment.
I've updated both comment and variable name to avoid confusion.
There was a problem hiding this comment.
nit: please capitalize var name to CheckNoLBRPos.
Also a nice way to settle this would be to simply add a test that covers this BAT mode case?
Could use split-file to tidy things up as well.
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
tdusnoki
force-pushed
the
fix-nolbr-merge
branch
from
c0356a5 to
f57a552
Compare
There was a problem hiding this comment.
Tests are target-agnostic, right?
If so, could you move them outside of the x86 folder?
Another suggestion would be to minimize the fdata files a bit.
And maybe introducing another fdata file to check that merging lbr/non-lbr profiles is not possible.
Thank you!
tdusnoki
force-pushed
the
fix-nolbr-merge
branch
2 times, most recently
from
6611933 to
b8ebec1
Compare
|
That was quick, thanks @tdusnoki ! I think though tests would now fail as you check on What I had in mind was something even simpler. And if your second non-lbr profile has something like |
tdusnoki
force-pushed
the
fix-nolbr-merge
branch
from
b8ebec1 to
67a8a34
Compare
tdusnoki
force-pushed
the
fix-nolbr-merge
branch
3 times, most recently
from
4e54c1b to
0489643
Compare
|
Just adding that there is a great overlap with: A difference (ignoring the formatting changes) is that |
tdusnoki
force-pushed
the
fix-nolbr-merge
branch
2 times, most recently
from
5a55e2a to
1ab6c85
Compare
…info When a basic sample profile is gathered without LBR info, the generated profile contains a "no-lbr" tag in the first line of the fdata file. This PR fixes merge-fdata to recognize and save this tag to the output file.
tdusnoki
force-pushed
the
fix-nolbr-merge
branch
from
1ab6c85 to
b986e8f
Compare
|
@tdusnoki Congratulations on having your first Pull Request (PR) merged into the LLVM Project! Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR. Please check whether problems have been caused by your change specifically, as the builds can include changes from many authors. It is not uncommon for your change to be included in a build that fails due to someone else's changes, or infrastructure issues. How to do this, and the rest of the post-merge process, is covered in detail here. If your change does cause a problem, it may be reverted, or you can revert it yourself. This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again. If you don't get any reports, no action is required from you. Your changes are working as expected, well done! |
When a basic sample profile is gathered without LBR info, the generated profile contains a "no-lbr" tag in the first line of the fdata file. This PR fixes merge-fdata to recognize and save this tag to the output file.