LLVM-PROFDATA(1)

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💅 LLVM-PROFDATA(1) — the profile data tool, but make it make sense

okay so real talk: this is the LLVM-PROFDATA(1) page from the LLVM manual, and it’s all about llvm-profdata. She’s a tiny utility, but she is booked and busy working with profile data files. Let’s get into it, bestie 🫶

✨ NAME ✨

llvm-profdata — profile data tool. That’s the name, that’s the vibe, and honestly? Iconic.

🦋 SYNOPSIS 🦋

llvm-profdata command [args...]

🌸 DESCRIPTION 🌸

The llvm-profdata tool is a small utility for working with profile data files. Small but mighty, no cap 💅

🎀 COMMANDS 🎀

There are four commands on the menu, and yes, you need to know them:

  • merge
  • show
  • overlap
  • order

🧚 MERGE 🧚

🦋 SYNOPSIS 🦋

llvm-profdata merge [options] [filename...]

🌸 DESCRIPTION 🌸

llvm-profdata merge takes several profile data files generated by PGO instrumentation and merges them together into a single indexed profile data file. It’s giving group project, but everyone actually contributes ✨

By default, profile data is merged without modification. This means that the relative importance of each input file is proportional to the number of samples or counts it contains. In general, the input from a longer training run will be interpreted as relatively more important than a shorter run. Depending on the nature of the training runs, it may be useful to adjust the weight given to each input file by using the -weighted-input option.

Profiles passed in via -weighted-input, -input-files, or via positional arguments are processed once for each time they are seen. noted, bestie — every appearance counts 👀

💅 OPTIONS 💅

Okay so this list is long, but every single flag matters. Let’s go 💖

  • --help — Print a summary of command line options. the “help me help you” button, always there for you 🫶
  • --output=<output>, -o — Specify the output file name. Output cannot be - as the resulting indexed profile data can't be written to standard output. so don’t try to be cute with stdout, it literally won’t work 😭
  • --weighted-input=<weight,filename> — Specify an input file name along with a weight. The profile counts of the supplied filename will be scaled (multiplied) by the supplied weight, where weight is a decimal integer >= 1. Input files specified without using this option are assigned a default weight of 1. Examples are shown below. this is how you make one profile the main character 👑
  • --input-files=<path>, -f — Specify a file which contains a list of files to merge. The entries in this file are newline-separated. Lines starting with # are skipped. Entries may be of the form <filename> or <weight>,<filename>.
  • --remapping-file=<path>, -r — Specify a file which contains a remapping from symbol names in the input profile to the symbol names that should be used in the output profile. The file should consist of lines of the form <input-symbol> <output-symbol>. Blank lines and lines starting with # are skipped.

The llvm-cxxmap <> tool can be used to generate the symbol remapping file. handy little helper, iykyk 🧚

  • --instr (default) — Specify that the input profile is an instrumentation-based profile.
  • --sample — Specify that the input profile is a sample-based profile.

The format of the generated file can be generated in one of three ways (the original says “three” and then lists four — we’re just the messenger 😭):

  • --binary (default) — Emit the profile using a binary encoding. For instrumentation-based profile the output format is the indexed binary format.
  • --extbinary — Emit the profile using an extensible binary encoding. This option can only be used with sample-based profile. The extensible binary encoding can be more compact with compression enabled and can be loaded faster than the default binary encoding.
  • --text — Emit the profile in text mode. This option can also be used with both sample-based and instrumentation-based profile. When this option is used the profile will be dumped in the text format that is parsable by the profile reader.
  • --gcc — Emit the profile using GCC's gcov format (Not yet supported). not yet, bestie — she’s still loading 💀
  • --sparse[=true|false] — Do not emit function records with 0 execution count. Can only be used in conjunction with -instr. Defaults to false, since it can inhibit compiler optimization during PGO. so like, careful — it can mess with optimization 👀
  • --num-threads=<N>, -j — Use N threads to perform profile merging. When N=0, llvm-profdata auto-detects an appropriate number of threads to use. This is the default. parallel queen behavior ✨
  • --failure-mode=[any|all] — Set the failure mode. There are two options: 'any' causes the merge command to fail if any profiles are invalid, and 'all' causes the merge command to fail only if all profiles are invalid. If 'all' is set, information from any invalid profiles is excluded from the final merged product. The default failure mode is 'any'.
  • --prof-sym-list=<path> — Specify a file which contains a list of symbols to generate profile symbol list in the profile. This option can only be used with sample-based profile in extbinary format. The entries in this file are newline-separated.
  • --compress-all-sections=[true|false] — Compress all sections when writing the profile. This option can only be used with sample-based profile in extbinary format.
  • --use-md5=[true|false] — Use MD5 to represent string in name table when writing the profile. This option can only be used with sample-based profile in extbinary format.
  • --gen-partial-profile=[true|false] — Mark the profile to be a partial profile which only provides partial profile coverage for the optimized target. This option can only be used with sample-based profile in extbinary format.
  • --split-layout=[true|false] — Split the profile data section to two with one containing sample profiles with inlined functions and the other not. This option can only be used with sample-based profile in extbinary format.
  • --convert-sample-profile-layout=[nest|flat] — Convert the merged profile into a profile with a new layout. Supported layout are nest (Nested profile, the input should be CS flat profile) and flat (Profile with nested inlinees flattened out).
  • --supplement-instr-with-sample=<file> — Supplement an instrumentation profile with sample profile. The sample profile is the input of the flag. Output will be in instrumentation format (only works with -instr).
  • --zero-counter-threshold=<float> — For the function which is cold in instr profile but hot in sample profile, if the ratio of the number of zero counters divided by the total number of counters is above the threshold, the profile of the function will be regarded as being harmful for performance and will be dropped. cold in one place, hot in another — make it make sense 😭
  • --instr-prof-cold-threshold=<int> — User specified cold threshold for instr profile which will override the cold threshold got from profile summary.
  • --suppl-min-size-threshold=<int> — If the size of a function is smaller than the threshold, assume it can be inlined by PGO early inliner and it will not be adjusted based on sample profile.
  • --debug-info=<path> — Specify the executable or .dSYM that contains debug info for the raw profile. When --debug-info-correlate or --profile-correlate=debug-info was used for instrumentation, use this option to correlate the raw profile.
  • --binary-file=<path> — Specify the executable that contains profile data and profile name sections for the raw profile. When -profile-correlate=binary was used for instrumentation, use this option to correlate the raw profile.
  • --debuginfod — Use debuginfod to find the associated executables that contain profile data and name sections for the raw profiles to correlate them. When -profile-correlate=binary was used for instrumentation, this option can be used for correlation.
  • --debug-file-directory=<dir> — Use provided local directories to search for executables that contain profile data and name sections for the raw profiles to correlate them. When -profile-correlate=binary was used for instrumentation, this option can be used for correlation.
  • --correlate=<kind> — Specify the correlation kind (debug_info or binary) to use when -debuginfod or -debug-file-directory=<dir> option is provided.
  • --temporal-profile-trace-reservoir-size — The maximum number of temporal profile traces to be stored in the output profile. If more traces are added, we will use reservoir sampling to select which traces to keep. Note that changing this value between different merge invocations on the same indexed profile could result in sample bias. The default value is 100.
  • --temporal-profile-max-trace-length — The maximum number of functions in a single temporal profile trace. Longer traces will be truncated. The default value is 1000.
  • --function=<string> — Only keep functions matching the regex in the output, all others are erased from the profile.
  • --no-function=<string> — Remove functions matching the regex from the profile. If both --function and --no-function are specified and a function matches both, it is removed. matching both? gone. no hesitation 💅

🎀 EXAMPLES 🎀

🌸 Basic Usage 🌸

Merge three profiles:

llvm-profdata merge foo.profdata bar.profdata baz.profdata -output merged.profdata

🦋 Weighted Input 🦋

The input file foo.profdata is especially important, multiply its counts by 10:

llvm-profdata merge --weighted-input=10,foo.profdata bar.profdata baz.profdata --output merged.profdata

Exactly equivalent to the previous invocation (explicit form; useful for programmatic invocation):

llvm-profdata merge --weighted-input=10,foo.profdata --weighted-input=1,bar.profdata --weighted-input=1,baz.profdata --output merged.profdata

✨ SHOW ✨

💅 SYNOPSIS

llvm-profdata show [options] [filename]

🎀 DESCRIPTION

llvm-profdata show grabs a profile data file and spills all the tea about it — specifically, the info about the profile counters for that file and for any function(s) you ask about. 👀

If filename is left out or is -, then llvm-profdata show reads its input from standard input. Very demure, very stdin. 💖

🌸 OPTIONS 🌸

  • --all-functions — prints the details for literally every function. All of them. No skipping. 👑
  • --binary-ids — prints the embedded binary ids chillin' inside a profile. 🦋
  • --counts — prints the counter values for the functions being displayed. The actual numbers, bestie. 🔥
  • --show-format=<text|json|yaml> — emits output in whichever format you pick, as long as the profile type you handed over actually supports it. 🙈
  • --function=<string> — prints details for a function if that function's name contains the given string. Substring matching, not exact — iykyk. 🔍
  • --help — prints a summary of the command line options. Your little safety net. 🫶
  • --output=<output>, -o — sets the output file name. If output is - or you just don't specify it, the output goes to standard output. ✨
  • --instr (default) — declares that the input profile is an instrumentation-based profile. This is the default btw, so if you say nothing, this is what you get. 🎀
  • --text — tells the profile dumper to show profile counts in the text format of the instrumentation-based profile data representation. By default, the profile info gets dumped in a more human-readable form (also in text) with annotations. Same text energy, different fit. 💅
  • --topn=<n> — tells the profile dumper to show the top n functions with the hottest basic blocks in the summary section. By default, the topn functions are not dumped. 🔥
  • --sample — declares that the input profile is a sample-based profile. 🧚
  • --memop-sizes — shows the profiled sizes of the memory intrinsic calls for the shown functions. 🍓
  • --value-cutoff=<n> — shows only those functions whose max count values are greater than or equal to n. By default, the value-cutoff is set to 0. ⭐
  • --list-below-cutoff — outputs only the names of functions whose max count value is below the cutoff value. Flip side of the vibe check. 🙃
  • --profile-version — prints the profile version. 📌
  • --showcs — only shows context sensitive profile counts. The default is to filter all context sensitive profile counts. 🌈
  • --show-prof-sym-list=[true|false] — shows the profile symbol list if one exists in the profile. This option is only meaningful for sample-based profile in extbinary format. 💜
  • --show-sec-info-only=[true|false] — shows basic information about each section in the profile. This option is only meaningful for sample-based profile in extbinary format. 🎀
  • --debug-info=<path> — specifies the executable or .dSYM that contains debug info for the raw profile. When --debug-info-correlate or --profile-correlate=debug-info was used for instrumentation, use this option to show the correlated functions from the raw profile. 🫶
  • --covered — shows only the functions that have actually been executed, i.e., functions with non-zero counts. Main character functions only. 👑

💖 OVERLAP 💖

🌟 SYNOPSIS

llvm-profdata overlap [options] [base profile file] [test profile file]

🦋 DESCRIPTION

llvm-profdata overlap takes two profile data files and displays the overlap of counter distribution between the whole files and between any of the specified functions. It's giving compatibility check, but for profiles. 💅

In this command, overlap is defined as follows: suppose the base profile file has the following counts:

{c1_1, c1_2, ..., c1_n, c1_u_1, c2_u_2, ..., c2_u_s}

and the test profile file has:

{c2_1, c2_2, ..., c2_n, c2_v_1, c2_v_2, ..., c2_v_t}

Here c{1|2}_i (i = 1 .. n) are matched counters and c1_u_i (i = 1 .. s) and c2_v_i (i = 1 .. v) are unmatched counters (or counters only existing in) the base profile file and the test profile file, respectively. Then:

sum_1 = c1_1 + c1_2 +  ... + c1_n +  c1_u_1 + c2_u_2 + ... + c2_u_s
sum_2 = c2_1 + c2_2 + ... + c2_n + c2_v_1 + c2_v_2 + ... + c2_v_t
overlap = min(c1_1/sum_1, c2_1/sum_2) + min(c1_2/sum_1, c2_2/sum_2) + ...  + min(c1_n/sum_1, c2_n/sum_2)

The resulting overlap distribution is a percentage number, ranging from 0.0% to 100.0%, where 0.0% means there is no overlap and 100.0% means a perfect overlap. No notes. 💯

Here's an example: if the base profile file has counts of {400, 600}, and the test profile file has matched counts of {60000, 40000}, the overlap is 80%. Math ate that fr fr. 🍓

🔥 OPTIONS 🔥

  • --function=<string> — prints details for a function if that function's name contains the given string. 🔍
  • --help — prints a summary of the command line options. 🫶
  • --output=<output>, -o — sets the output file name. If output is - or you didn't specify it, the output goes to standard output. ✨
  • --value-cutoff=<n> — shows only those functions whose max count values are greater than or equal to n. By default, the value-cutoff is set to max of unsigned long long. Yeah, the whole entire max. 😭
  • --cs — only shows overlap for the context sensitive profile counts. The default is to show non-context sensitive profile counts. 🌀

🧚 ORDER 🧚

⭐ SYNOPSIS

llvm-profdata order [options] [filename]

💜 DESCRIPTION

llvm-profdata order uses temporal profiling traces from a profile and finds a function order that reduces the number of page faults for those traces. Obsessed with efficiency. 🔥

This output can be passed directly to lld via --symbol-ordering-file= for ELF or -order-file for Mach-O. And if the traces found in the profile are representative of the real world, then this order should improve startup performance. Slay. 👑

🌈 OPTIONS 🌈

  • --help — prints a summary of the command line options. 🫶
  • --output=<output>, -o — sets the output file name. If output is - or you didn't specify it, the output goes to standard output. ✨

💀 EXIT STATUS 💀

llvm-profdata returns 1 if the command is omitted or is invalid, if it cannot read input files, or if there is a mismatch between their data. So basically: no command, bad command, can't read, or the files don't agree. Not the vibe. 😭

Author — maintained by the LLVM Team (https://llvm.org/). We love a maintained-by-the-team moment. 💖 Copyright — 2003-2026, LLVM Project.

And that's the whole page, bestie — signed, sealed, delivered from page 23, dated 2026-10-20, filed under LLVM-PROFDATA(1). Go forth and profile responsibly. 💅✨🎀

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