llvm-bolt <executable> [-o outputfile] <executable>.bolt [-data=perf.fdata] [options]
-h
Alias for --help
--help
Display available options (--help-hidden for more)
--help-hidden
Display all available options
--help-list
Display list of available options (--help-list-hidden for more)
--help-list-hidden
Display list of all available options
--version
Display the version of this program
--bolt-info
Write bolt info section in the output binary
-o <string>
output file
-w <string>
Save recorded profile to a file
--align-text=<uint>
Alignment of .text section
--allow-stripped
Allow processing of stripped binaries
--alt-inst-feature-size=<uint>
Size of feature field in .altinstructions
--alt-inst-has-padlen
Specify that .altinstructions has padlen field
--asm-dump[=<dump folder>]
Dump function into assembly
-b
Alias for -data
--bolt-id=<string>
Add any string to tag this execution in the output binary via bolt info section
--break-funcs=<func1,func2,func3,...>
List of functions to core dump on (debugging)
--check-encoding
Perform verification of LLVM instruction encoding/decoding. Every instruction in the input is decoded and re-encoded. If the resulting bytes do not match the input, a warning message is printed.
--comp-dir-override=<string>
Overrides DW_AT_comp_dir, and provides an alternative base location, which is used with DW_AT_dwo_name to construct a path to *.dwo files.
--create-debug-names-section
Creates .debug_names section, if the input binary doesn't have it already, for DWARF5 CU/TUs.
--cu-processing-batch-size=<uint>
Specifies the size of batches for processing CUs. Higher number has better performance, but more memory usage. Default value is 1.
--data=<string>
data file
--data2=<string>
data file
--debug-skeleton-cu
Prints out offsets for abbrev and debug_info of Skeleton CUs that get patched.
--debug-thread-count=<uint>
Specifies the number of threads to be used when processing DWO debug information.
--dot-tooltip-code
Add basic block instructions as tool tips on nodes
--dump-alt-instructions
Dump Linux alternative instructions info
--dump-cg=<string>
Dump callgraph to the given file
--dump-data
Dump parsed bolt data for debugging
--dump-dot-all
Dump function CFGs to graphviz format after each stage;enable ‘-print-loops’ for color-coded blocks
--dump-linux-exceptions
Dump Linux kernel exception table
--dump-orc
Dump raw ORC unwind information (sorted)
--dump-para-sites
Dump Linux kernel paravitual patch sites
--dump-pci-fixups
Dump Linux kernel PCI fixup table
--dump-smp-locks
Dump Linux kernel SMP locks
--dump-static-calls
Dump Linux kernel static calls
--dump-static-keys
Dump Linux kernel static keys jump table
--dwarf-output-path=<string>
Path to where .dwo files or dwp file will be written out to.
--dwp=<string>
Path and name to DWP file.
--dyno-stats
Print execution info based on profile
--dyno-stats-all
Print dyno stats after each stage
--dyno-stats-scale=<uint>
Scale to be applied while reporting dyno stats
--enable-bat
Write BOLT Address Translation tables
--force-data-relocations
Force relocations to data sections to always be processed
--force-patch
Force patching of original entry points
--funcs=<func1,func2,func3,...>
Limit optimizations to functions from the list
--funcs-file=<string>
File with list of functions to optimize
--funcs-file-no-regex=<string>
File with list of functions to optimize (non-regex)
--funcs-no-regex=<func1,func2,func3,...>
Limit optimizations to functions from the list (non-regex)
--hot-data
Hot data symbols support (relocation mode)
--hot-functions-at-end
If reorder-functions is used, order functions putting hottest last
--hot-text
Generate hot text symbols. Apply this option to a precompiled binary that manually calls into hugify, such that at runtime hugify call will put hot code into 2M pages. This requires relocation.
--hot-text-move-sections=<sec1,sec2,sec3,...>
List of sections containing functions used for hugifying hot text. BOLT makes sure these functions are not placed on the same page as the hot text. (default=‘.stub,.mover’).
--insert-retpolines
Run retpoline insertion pass
--keep-aranges
Keep or generate .debug_aranges section if .gdb_index is written
--keep-tmp
Preserve intermediate .o file
--lite
Skip processing of cold functions
--log-file=<string>
Redirect journaling to a file instead of stdout/stderr
--long-jump-labels
Always use long jumps/nops for Linux kernel static keys
--match-profile-with-function-hash
Match profile with function hash
--max-data-relocations=<uint>
Maximum number of data relocations to process
--max-funcs=<uint>
Maximum number of functions to process
--no-huge-pages
Use regular size pages for code alignment
--no-threads
Disable multithreading
--pad-funcs=<func1:pad1,func2:pad2,func3:pad3,...>
List of functions to pad with amount of bytes
--print-mappings
Print mappings in the legend, between characters/blocks and text sections (default false).
--profile-format=<value>
Format to dump profile output in aggregation mode, default is fdata
fdata
: offset-based plaintext formatyaml
: dense YAML representation--r11-availability=<value>
Determine the availability of r11 before indirect branches
never
: r11 not availablealways
: r11 available before calls and jumpsabi
: r11 available before calls but not before jumps--relocs
Use relocations in the binary (default=autodetect)
--remove-symtab
Remove .symtab section
--reorder-skip-symbols=<symbol1,symbol2,symbol3,...>
List of symbol names that cannot be reordered
--reorder-symbols=<symbol1,symbol2,symbol3,...>
List of symbol names that can be reordered
--retpoline-lfence
Determine if lfence instruction should exist in the retpoline
--skip-funcs=<func1,func2,func3,...>
List of functions to skip
--skip-funcs-file=<string>
File with list of functions to skip
--strict
Trust the input to be from a well-formed source
--tasks-per-thread=<uint>
Number of tasks to be created per thread
--terminal-trap
Assume that execution stops at trap instruction
--thread-count=<uint>
Number of threads
--top-called-limit=<uint>
Maximum number of functions to print in top called functions section
--trap-avx512
In relocation mode trap upon entry to any function that uses AVX-512 instructions
--trap-old-code
Insert traps in old function bodies (relocation mode)
--update-debug-sections
Update DWARF debug sections of the executable
--use-gnu-stack
Use GNU_STACK program header for new segment (workaround for issues with strip/objcopy)
--use-old-text
Re-use space in old .text if possible (relocation mode)
-v <uint>
Set verbosity level for diagnostic output
--write-dwp
Output a single dwarf package file (dwp) instead of multiple non-relocatable dwarf object files (dwo).
--align-blocks
Align basic blocks
--align-blocks-min-size=<uint>
Minimal size of the basic block that should be aligned
--align-blocks-threshold=<uint>
Align only blocks with frequency larger than containing function execution frequency specified in percent. E.g. 1000 means aligning blocks that are 10 times more frequently executed than the containing function.
--align-functions=<uint>
Align functions at a given value (relocation mode)
--align-functions-max-bytes=<uint>
Maximum number of bytes to use to align functions
--assume-abi
Assume the ABI is never violated
--block-alignment=<uint>
Boundary to use for alignment of basic blocks
--bolt-seed=<uint>
Seed for randomization
--cg-from-perf-data
Use perf data directly when constructing the call graph for stale functions
--cg-ignore-recursive-calls
Ignore recursive calls when constructing the call graph
--cg-use-split-hot-size
Use hot/cold data on basic blocks to determine hot sizes for call graph functions
--cold-threshold=<uint>
Tenths of percents of main entry frequency to use as a threshold when evaluating whether a basic block is cold (0 means it is only considered cold if the block has zero samples). Default: 0
--elim-link-veneers
Run veneer elimination pass
--eliminate-unreachable
Eliminate unreachable code
--equalize-bb-counts
Use same count for BBs that should have equivalent count (used in non-LBR and shrink wrapping)
--execution-count-threshold=<uint>
Perform profiling accuracy-sensitive optimizations only if function execution count >= the threshold (default: 0)
--fix-block-counts
Adjust block counts based on outgoing branch counts
--fix-func-counts
Adjust function counts based on basic blocks execution count
--force-inline=<func1,func2,func3,...>
List of functions to always consider for inlining
--frame-opt=<value>
Optimize stack frame accesses
none
: do not perform frame optimizationhot
: perform FOP on hot functionsall
: perform FOP on all functions--frame-opt-rm-stores
Apply additional analysis to remove stores (experimental)
--function-order=<string>
File containing an ordered list of functions to use for function reordering
--generate-function-order=<string>
File to dump the ordered list of functions to use for function reordering
--generate-link-sections=<string>
Generate a list of function sections in a format suitable for inclusion in a linker script
--group-stubs
Share stubs across functions
--hugify
Automatically put hot code on 2MB page(s) (hugify) at runtime. No manual call to hugify is needed in the binary (which is what --hot-text relies on).
--icf
Fold functions with identical code
--icp
Alias for --indirect-call-promotion
--icp-calls-remaining-percent-threshold=<uint>
The percentage threshold against remaining unpromoted indirect call count for the promotion for calls
--icp-calls-topn
Alias for --indirect-call-promotion-calls-topn
--icp-calls-total-percent-threshold=<uint>
The percentage threshold against total count for the promotion for calls
--icp-eliminate-loads
Enable load elimination using memory profiling data when performing ICP
--icp-funcs=<func1,func2,func3,...>
List of functions to enable ICP for
--icp-inline
Only promote call targets eligible for inlining
--icp-jt-remaining-percent-threshold=<uint>
The percentage threshold against remaining unpromoted indirect call count for the promotion for jump tables
--icp-jt-targets
Alias for --icp-jump-tables-targets
--icp-jt-topn
Alias for --indirect-call-promotion-jump-tables-topn
--icp-jt-total-percent-threshold=<uint>
The percentage threshold against total count for the promotion for jump tables
--icp-jump-tables-targets
For jump tables, optimize indirect jmp targets instead of indices
--icp-mp-threshold
Alias for --indirect-call-promotion-mispredict-threshold
--icp-old-code-sequence
Use old code sequence for promoted calls
--icp-top-callsites=<uint>
Optimize hottest calls until at least this percentage of all indirect calls frequency is covered. 0 = all callsites
--icp-topn
Alias for --indirect-call-promotion-topn
--icp-use-mp
Alias for --indirect-call-promotion-use-mispredicts
--indirect-call-promotion=<value>
Indirect call promotion
none
: do not perform indirect call promotioncalls
: perform ICP on indirect callsjump-tables
: perform ICP on jump tablesall
: perform ICP on calls and jump tables--indirect-call-promotion-calls-topn=<uint>
Limit number of targets to consider when doing indirect call promotion on calls. 0 = no limit
--indirect-call-promotion-jump-tables-topn=<uint>
Limit number of targets to consider when doing indirect call promotion on jump tables. 0 = no limit
--indirect-call-promotion-topn=<uint>
Limit number of targets to consider when doing indirect call promotion. 0 = no limit
--indirect-call-promotion-use-mispredicts
Use misprediction frequency for determining whether or not ICP should be applied at a callsite. The -indirect-call-promotion-mispredict-threshold value will be used by this heuristic
--infer-fall-throughs
Infer execution count for fall-through blocks
--infer-stale-profile
Infer counts from stale profile data.
--inline-all
Inline all functions
--inline-ap
Adjust function profile after inlining
--inline-limit=<uint>
Maximum number of call sites to inline
--inline-max-iters=<uint>
Maximum number of inline iterations
--inline-memcpy
Inline memcpy using ‘rep movsb’ instruction (X86-only)
--inline-small-functions
Inline functions if increase in size is less than defined by -inline-small- functions-bytes
--inline-small-functions-bytes=<uint>
Max number of bytes for the function to be considered small for inlining purposes
--instrument
Instrument code to generate accurate profile data
--iterative-guess
In non-LBR mode, guess edge counts using iterative technique
--jt-footprint-optimize-for-icache
With jt-footprint-reduction, only process PIC jumptables and turn off other transformations that increase code size
--jt-footprint-reduction
Make jump tables size smaller at the cost of using more instructions at jump sites
--jump-tables=<value>
Jump tables support (default=basic)
none
: do not optimize functions with jump tablesbasic
: optimize functions with jump tablesmove
: move jump tables to a separate sectionsplit
: split jump tables section into hot and cold based on function execution frequencyaggressive
: aggressively split jump tables section based on usage of the tables--keep-nops
Keep no-op instructions. By default they are removed.
--lite-threshold-count=<uint>
Similar to ‘-lite-threshold-pct’ but specify threshold using absolute function call count. I.e. limit processing to functions executed at least the specified number of times.
--lite-threshold-pct=<uint>
Threshold (in percent) for selecting functions to process in lite mode. Higher threshold means fewer functions to process. E.g threshold of 90 means only top 10 percent of functions with profile will be processed.
--match-with-call-graph
Match functions with call graph
--memcpy1-spec=<func1,func2:cs1:cs2,func3:cs1,...>
List of functions with call sites for which to specialize memcpy() for size 1
--min-branch-clusters
Use a modified clustering algorithm geared towards minimizing branches
--name-similarity-function-matching-threshold=<uint>
Match functions using namespace and edit distance.
--no-inline
Disable all inlining (overrides other inlining options)
--no-scan
Do not scan cold functions for external references (may result in slower binary)
--peepholes=<value>
Enable peephole optimizations
none
: disable peepholesdouble-jumps
: remove double jumps when abletailcall-traps
: insert tail call trapsuseless-branches
: remove useless conditional branchesall
: enable all peephole optimizations--plt=<value>
Optimize PLT calls (requires linking with -znow)
none
: do not optimize PLT callshot
: optimize executed (hot) PLT callsall
: optimize all PLT calls--preserve-blocks-alignment
Try to preserve basic block alignment
--profile-ignore-hash
Ignore hash while reading function profile
--profile-use-dfs
Use DFS order for YAML profile
--reg-reassign
Reassign registers so as to avoid using REX prefixes in hot code
--reorder-blocks=<value>
Change layout of basic blocks in a function
none
: do not reorder basic blocksreverse
: layout blocks in reverse ordernormal
: perform optimal layout based on profilebranch-predictor
: perform optimal layout prioritizing branch predictionscache
: perform optimal layout prioritizing I-cache behaviorcache+
: perform layout optimizing I-cache behaviorext-tsp
: perform layout optimizing I-cache behaviorcluster-shuffle
: perform random layout of clusters--reorder-data=<section1,section2,section3,...>
List of sections to reorder
--reorder-data-algo=<value>
Algorithm used to reorder data sections
count
: sort hot data by read countsfuncs
: sort hot data by hot function usage and count--reorder-data-inplace
Reorder data sections in place
--reorder-data-max-bytes=<uint>
Maximum number of bytes to reorder
--reorder-data-max-symbols=<uint>
Maximum number of symbols to reorder
--reorder-functions=<value>
Reorder and cluster functions (works only with relocations)
none
: do not reorder functionsexec-count
: order by execution counthfsort
: use hfsort algorithmhfsort+
: use cache-directed sortcdsort
: use cache-directed sortpettis-hansen
: use Pettis-Hansen algorithmrandom
: reorder functions randomlyuser
: use function order specified by -function-order--reorder-functions-use-hot-size
Use a function's hot size when doing clustering
--report-bad-layout=<uint>
Print top functions with suboptimal code layout on input
--report-stale
Print the list of functions with stale profile
--runtime-hugify-lib=<string>
Specify file name of the runtime hugify library
--runtime-instrumentation-lib=<string>
Specify file name of the runtime instrumentation library
--sctc-mode=<value>
Mode for simplify conditional tail calls
always
: always perform sctcpreserve
: only perform sctc when branch direction is preservedheuristic
: use branch prediction data to control sctc--sequential-disassembly
Performs disassembly sequentially
--shrink-wrapping-threshold=<uint>
Percentage of prologue execution count to use as threshold when evaluating whether a block is cold enough to be profitable to move eligible spills there
--simplify-conditional-tail-calls
Simplify conditional tail calls by removing unnecessary jumps
--simplify-rodata-loads
Simplify loads from read-only sections by replacing the memory operand with the constant found in the corresponding section
--split-align-threshold=<uint>
When deciding to split a function, apply this alignment while doing the size comparison (see -split-threshold). Default value: 2.
--split-all-cold
Outline as many cold basic blocks as possible
--split-eh
Split C++ exception handling code
--split-functions
Split functions into fragments
--split-strategy=<value>
Strategy used to partition blocks into fragments
profile2
: split each function into a hot and cold fragment using profiling informationcdsplit
: split each function into a hot, warm, and cold fragment using profiling informationrandom2
: split each function into a hot and cold fragment at a randomly chosen split point (ignoring any available profiling information)randomN
: split each function into N fragments at a randomly chosen split points (ignoring any available profiling information)all
: split all basic blocks of each function into fragments such that each fragment contains exactly a single basic block--split-threshold=<uint>
Split function only if its main size is reduced by more than given amount of bytes. Default value: 0, i.e. split iff the size is reduced. Note that on some architectures the size can increase after splitting.
--stale-matching-max-func-size=<uint>
The maximum size of a function to consider for inference.
--stale-matching-min-matched-block=<uint>
Percentage threshold of matched basic blocks at which stale profile inference is executed.
--stale-threshold=<uint>
Maximum percentage of stale functions to tolerate (default: 100)
--stoke
Turn on the stoke analysis
--strip-rep-ret
Strip ‘repz’ prefix from ‘repz retq’ sequence (on by default)
--tail-duplication=<value>
Duplicate unconditional branches that cross a cache line
none
: do not applyaggressive
: aggressive strategymoderate
: moderate strategycache
: cache-aware duplication strategy--tsp-threshold=<uint>
Maximum number of hot basic blocks in a function for which to use a precise TSP solution while re-ordering basic blocks
--use-aggr-reg-reassign
Use register liveness analysis to try to find more opportunities for -reg- reassign optimization
--use-compact-aligner
Use compact approach for aligning functions
--use-edge-counts
Use edge count data when doing clustering
--verify-cfg
Verify the CFG after every pass
--x86-align-branch-boundary-hot-only
Only apply branch boundary alignment in hot code
--x86-strip-redundant-address-size
Remove redundant Address-Size override prefix
--align-macro-fusion=<value>
Fix instruction alignment for macro-fusion (x86 relocation mode)
none
: do not insert alignment no-ops for macro-fusionhot
: only insert alignment no-ops on hot execution paths (default)all
: always align instructions to allow macro-fusionllvm-bolt <executable> -instrument [-o outputfile] <instrumented-executable>
--conservative-instrumentation
Disable instrumentation optimizations that sacrifice profile accuracy (for debugging, default: false)
--instrument-calls
Record profile for inter-function control flow activity (default: true)
--instrument-hot-only
Only insert instrumentation on hot functions (needs profile, default: false)
--instrumentation-binpath=<string>
Path to instrumented binary in case if /proc/self/map_files is not accessible due to access restriction issues
--instrumentation-file=<string>
File name where instrumented profile will be saved (default: /tmp/prof.fdata)
--instrumentation-file-append-pid
Append PID to saved profile file name (default: false)
--instrumentation-no-counters-clear
Don't clear counters across dumps (use with instrumentation-sleep-time option)
--instrumentation-sleep-time=<uint>
Interval between profile writes (default: 0 = write only at program end). This is useful for service workloads when you want to dump profile every X minutes or if you are killing the program and the profile is not being dumped at the end.
--instrumentation-wait-forks
Wait until all forks of instrumented process will finish (use with instrumentation-sleep-time option)
--print-aliases
Print aliases when printing objects
--print-all
Print functions after each stage
--print-cfg
Print functions after CFG construction
--print-debug-info
Print debug info when printing functions
--print-disasm
Print function after disassembly
--print-dyno-opcode-stats=<uint>
Print per instruction opcode dyno stats and the functionnames:BB offsets of the nth highest execution counts
--print-dyno-stats-only
While printing functions output dyno-stats and skip instructions
--print-exceptions
Print exception handling data
--print-globals
Print global symbols after disassembly
--print-jump-tables
Print jump tables
--print-loops
Print loop related information
--print-mem-data
Print memory data annotations when printing functions
--print-normalized
Print functions after CFG is normalized
--print-only=<func1,func2,func3,...>
List of functions to print
--print-orc
Print ORC unwind information for instructions
--print-profile
Print functions after attaching profile
--print-profile-stats
Print profile quality/bias analysis
--print-pseudo-probes=<value>
Print pseudo probe info
decode
: decode probes section from binaryaddress_conversion
: update address2ProbesMap with output block addressencoded_probes
: display the encoded probes in binary sectionall
: enable all debugging printout--print-relocations
Print relocations when printing functions/objects
--print-reordered-data
Print section contents after reordering
--print-retpoline-insertion
Print functions after retpoline insertion pass
--print-sdt
Print all SDT markers
--print-sections
Print all registered sections
--print-unknown
Print names of functions with unknown control flow
--time-build
Print time spent constructing binary functions
--time-rewrite
Print time spent in rewriting passes
--print-after-branch-fixup
Print function after fixing local branches
--print-after-jt-footprint-reduction
Print function after jt-footprint-reduction pass
--print-after-lowering
Print function after instruction lowering
--print-cache-metrics
Calculate and print various metrics for instruction cache
--print-clusters
Print clusters
--print-estimate-edge-counts
Print function after edge counts are set for no-LBR profile
--print-finalized
Print function after CFG is finalized
--print-fix-relaxations
Print functions after fix relaxations pass
--print-fix-riscv-calls
Print functions after fix RISCV calls pass
--print-fop
Print functions after frame optimizer pass
--print-function-statistics=<uint>
Print statistics about basic block ordering
--print-icf
Print functions after ICF optimization
--print-icp
Print functions after indirect call promotion
--print-inline
Print functions after inlining optimization
--print-large-functions
Print functions that could not be overwritten due to excessive size
--print-longjmp
Print functions after longjmp pass
--print-optimize-bodyless
Print functions after bodyless optimization
--print-output-address-range
Print output address range for each basic block in the function whenBinaryFunction::print is called
--print-peepholes
Print functions after peephole optimization
--print-plt
Print functions after PLT optimization
--print-regreassign
Print functions after regreassign pass
--print-reordered
Print functions after layout optimization
--print-reordered-functions
Print functions after clustering
--print-sctc
Print functions after conditional tail call simplification
--print-simplify-rodata-loads
Print functions after simplification of RO data loads
--print-sorted-by=<value>
Print functions sorted by order of dyno stats
executed-forward-branches
: executed forward branchestaken-forward-branches
: taken forward branchesexecuted-backward-branches
: executed backward branchestaken-backward-branches
: taken backward branchesexecuted-unconditional-branches
: executed unconditional branchesall-function-calls
: all function callsindirect-calls
: indirect callsPLT-calls
: PLT callsexecuted-instructions
: executed instructionsexecuted-load-instructions
: executed load instructionsexecuted-store-instructions
: executed store instructionstaken-jump-table-branches
: taken jump table branchestaken-unknown-indirect-branches
: taken unknown indirect branchestotal-branches
: total branchestaken-branches
: taken branchesnon-taken-conditional-branches
: non-taken conditional branchestaken-conditional-branches
: taken conditional branchesall-conditional-branches
: all conditional brancheslinker-inserted-veneer-calls
: linker-inserted veneer callsall
: sorted by all names--print-sorted-by-order=<value>
Use ascending or descending order when printing functions ordered by dyno stats
--print-split
Print functions after code splitting
--print-stoke
Print functions after stoke analysis
--print-uce
Print functions after unreachable code elimination
--print-veneer-elimination
Print functions after veneer elimination pass
--time-opts
Print time spent in each optimization
--print-all-options
Print all option values after command line parsing
--print-options
Print non-default options after command line parsing