LLVM-PROFDATA(1)

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🦋 llvm-profdata — LLVM's profile data tool 🦋

okay so this is the LLVM manual page for llvm-profdata, and it's giving main character energy for a small utility. We're gonna go through every command, flag, default, and example, bestie — no skips, no cap. 💖

🌸 NAME 🌸

llvm-profdata — profile data tool. That's the whole name section, short and iconic. 🎀

✨ SYNOPSIS ✨

llvm-profdata command [args…]

yes bestie, it's command plus args…. That's the vibe. 💅

💖 DESCRIPTION 💖

The llvm-profdata tool is a small utility for working with profile data files. Lowkey tiny, highkey useful. 🦋

🫶 COMMANDS 🫶

Three commands live here:

  • merge
  • show
  • overlap

🔥 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 literally the group-chat merge of profiles. 💖

By default, profile data is merged without modification. That means the relative importance of each input file is proportional to the number of samples or counts it contains. So generally, input from a longer training run is interpreted as relatively more important than a shorter run. Depending on what those training runs are like, it may be useful to adjust the weight given to each input file with the -weighted-input option. Ngl, weights are where the drama is. 👑

Profiles passed in via -weighted-input, -input-files, or via positional arguments are processed once for each time they are seen. Periodt.

🎀 OPTIONS 🎀

okay bestie, here's the full flag lineup:

  • -help — Print a summary of command line options.
  • -output=output, -o=output — Specify the output file name. Output cannot be -, because the resulting indexed profile data can't be written to standard output.
  • -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. ✨
  • -input-files=path, -f=path — 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=path — 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. 🫶

  • -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:

  • -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). 💀
  • -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.
  • -num-threads=N, -j=N — 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.
  • -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.
  • -supplement-instr-with-sample=path_to_sample_profile — 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=threshold_float_number — 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.
  • -instr-prof-cold-threshold=threshold_int_number — User specified cold threshold for instr profile which will override the cold threshold got from profile summary.
  • -suppl-min-size-threshold=threshold_int_number — 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.

🦋 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, so 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 takes a profile data file and displays the information about the profile counters for this file and for any of the specified function(s). It's the nosy bestie of commands, and we love her. 🔥

If filename is omitted or is -, then llvm-profdata show reads its input from standard input. 🫶

🍓 OPTIONS 🍓

  • -all-functions — Print details for every function.
  • -counts — Print the counter values for the displayed functions.
  • -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=output — Specify the output file name. If output is - or it isn't specified, then the output is sent to standard output.
  • -instr (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.
  • -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 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.
  • -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. 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. This option is only meaningful for sample-based profile in extbinary format.

🦋 OVERLAP 🦋

✨ SYNOPSIS ✨

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

💖 DESCRIPTION 💖

okay so llvm-profdata overlap takes two profile data files and shows you the overlap of counter distribution — both for the whole files and for any functions you specifically ask about. it's giving "how much do these two profiles actually vibe with each other" 💅

so in this command, overlap means this, and bestie i'm gonna need you to focus for a sec:

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 the matched counters, and c1_u_i (i = 1 .. s) and c2_v_i (i = 1 .. v) are the unmatched counters — meaning the counters that only exist in the base profile file and the 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. Then:

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 🌈

here's a lil example so it actually clicks: if base profile file has counts of {400, 600}, and test profile file has matched counts of {60000, 40000}, the overlap is 80%. slay 💅

🎀 OPTIONS 🎀

  • -function=string — prints details for a function if the function's name contains the given string. cute lil filter, iykyk ✨
  • -help — prints a summary of command line options. the classic "what do i even do here" button 🙈
  • -o=output or -o output — specifies the output file name. if output is - or it isn't specified at all, then the output goes straight to standard output 💖
  • -value-cutoff=n — shows only those functions whose max count values are greater or equal to n. by default, the value-cutoff is set to the max of unsigned long long (so, literally everything gets shown — no filter, no cap 🧢)
  • -cs — only show overlap for the context sensitive profile counts. the default is to show non-context sensitive profile counts. pick your fighter 👑

💀 EXIT STATUS 💀

llvm-profdata returns 1 if the command is omitted or is invalid, if it cannot read input files, or if there's a mismatch between their data. like yeah she's dramatic but she's also correct 😭

👑 AUTHOR 👑

Maintained by the LLVM Team (https://llvm.org/). legends, fr fr 🫶

2003-2023, LLVM Project

and that's the whole page bestie!! 🎀 this was from the LLVM Project, dated 2023-07-14, and you were reading LLVM-PROFDATA(1) — go forth and profile beautifully 💜✨🦋

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