LLVM-PROFDATA(1)

📦
version 18.1.8 · 10 versions
, in ubuntu stonking

okay bestie, welcome to the LLVM-PROFDATA(1) page — aka the manual for llvm-profdata, the tiny utility that is genuinely obsessed with working with profile data files. Think of it as the group-chat admin for your profile data: small, useful, and absolutely not here to waste your time. 💅

✨ NAME ✨

llvm-profdata — the Profile data tool. no cap, that's the whole name-and-game. 🎀

🦋 SYNOPSIS 🦋

llvm-profdata command [args...]

🌸 DESCRIPTION 🌸

The llvm-profdata tool is a small utility for working with profile data files. that's it, that's the vibe — small utility, profile data files, all very slay. ✨

💅 COMMANDS 💅

Here's the command squad, bestie:

  • 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 glow-up through consolidation. 💖

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. literally once per appearance, bestie — no sneaky double-counting unless you literally list it again. 🫶

OPTIONS

  • --help — Print a summary of command line options. your little “what are my choices” moment. 🧚
  • --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 nope, bestie, - is not it here. 🙈
  • --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 the “give this file main-character energy” knob. 🔥
  • --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>. like a little merge playlist, but make it text. 🎀
  • --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. so yes, there's a helper for that remap moment. 🦋

  • --instr (default) — Specify that the input profile is an instrumentation-based profile. this is the default vibe. ⭐
  • --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:

  • --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. fancy and fast, iykyk. ⚡
  • --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. human-readable-ish, slay. 📝
  • --gcc — Emit the profile using GCC's gcov format (Not yet supported). it's giving “coming eventually,” not “available now,” bestie. 💀
  • --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 the default is false for a real reason — don't just flip it for fun. ⚠️
  • --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 merge era, periodt. 🌈
  • --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'. choose your chaos level carefully. 💅
  • --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. tiny file energy. 🗜️
  • --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. partial coverage, fully intentional. 🌸
  • --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). choose your layout like you're choosing an aesthetic. 🦋
  • --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). combo move, but read the parenthetical. 👑
  • --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. dramatic? yes. accurate? also yes. 💀
  • --instr-prof-cold-threshold=<int> — User specified cold threshold for instr profile which will override the cold threshold got from profile summary. your threshold, your rules. 🔥
  • --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. smol function privileges. 🍓
  • --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. ✨
  • --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.
bestie, that sample-bias note is real — don't casually change this between merges on the same indexed profile and expect everything to be chill. 😭
  • --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. keep the chosen ones, delete the rest. 💅
  • --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. so matching both = gone, no debate. 🫶

EXAMPLES

Basic Usage

Merge three profiles:

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

that's the classic “three files walk into a merge” moment. 🎀

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

Okay bestie, llvm-profdata show is literally the "let me look at it" of the profile world 💅 — you hand it a profile data file and it displays all the info about the profile counters for that file, and for any of the function(s) you specify.

And if filename is omitted or it's -? Then llvm-profdata show reads its input from standard input. Slay, stdin gang 🫶

OPTIONS

  • --all-functions — print details for every function. All of them. No skips, no crumbs left behind ✨
  • --binary-ids — print the embedded binary ids chillin' in a profile.
  • --counts — print the counter values for the displayed functions.
  • --show-format=<text|json|yaml> — emit output in the selected format, if it's supported by the profile type you handed over 🙈
  • --function=<string> — print details for a function if the function's name contains the given string.
  • --help — print a summary of command line options. A little map of the vibes 🎀
  • --output=<output>, -o — specify the output file name. If output is - or it isn't specified, then the output is sent to standard output.
  • --instr (the default) — specify that the input profile is an instrumentation-based profile.
  • --text — instruct the profile dumper to show profile counts in the text format of the instrumentation-based profile data representation. By default, the profile information is dumped in a more human readable form (also in text) with annotations. Either way it's text, bestie, don't panic 💖
  • --topn=<n> — instruct 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 — specify that the input profile is a sample-based profile.
  • --memop-sizes — show the profiled sizes of the memory intrinsic calls for the shown functions.
  • --value-cutoff=<n> — show only those functions whose max count values are greater or equal to n. By default, the value-cutoff is set to 0.
  • --list-below-cutoff — only output names of functions whose max count value are below the cutoff value. Chaos gremlin mode, iconic honestly 🦋
  • --profile-version — print profile version.
  • --showcs — only show context sensitive profile counts. The default is to filter all context sensitive profile counts.
  • --show-prof-sym-list=[true|false] — show profile symbol list if it exists in the profile. Heads up: this option is only meaningful for sample-based profile in extbinary format.
  • --show-sec-info-only=[true|false] — show basic information about each section in the profile. Also only meaningful for sample-based profile in extbinary format, iykyk.
  • --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 show the correlated functions from the raw profile.
  • --covered — show 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 make it data 🔥

So in this command, overlap is defined like this, and I'm quoting the math exactly because she is that girl:

Suppose base profile file has the following counts: {c1_1, c1_2, ..., c1_n, c1_u_1, c2_u_2, ..., c2_u_s}, and 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) base profile file and test profile file, respectively.

Let sum_1 = c1_1 + c1_2 +  ... + c1_n +  c1_u_1 + c2_u_2
+ ... + c2_u_s, and 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 result 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. Perfect overlap? We love to see it 💖

Here's the example, fr fr: if base profile file has counts of {400, 600}, and test profile file has matched counts of {60000, 40000}, the overlap is 80%. Math ate and left no crumbs ✨

OPTIONS

  • --function=<string> — print details for a function if the function's name contains the given string.
  • --help — print a summary of command line options.
  • --output=<output>, -o — specify the output file name. If output is - or it isn't specified, then the output is sent to standard output.
  • --value-cutoff=<n> — show only those functions whose max count values are greater or equal to n. By default, the value-cutoff is set to max of unsigned long long. Yes, max, she is not playing around 😭
  • --cs — only show 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. Lowkey a glow-up for your binary's memory behaviour 🌈

This output can be directly passed 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. Faster startup = main character energy, no cap 👑

OPTIONS

  • --help — print a summary of command line options.
  • --output=<output>, -o — specify the output file name. If output is - or it isn't specified, then the output is sent 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 a 1 means something's not giving — go check your inputs bestie 🫶

🌟 Author 🌟

Maintained by the LLVM Team (https://llvm.org/). Shoutout to the maintainers, absolute icons 💜

2003-2026, LLVM Project.

That's the whole page, bestie — go profile something iconic 💅✨

Source/version line: this gem lives at 15, dated 2026-09-09, filed under LLVM-PROFDATA(1). Mwah, see you in the man pages 💖

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