LLVM-BCANALYZER(1) LLVM LLVM-BCANALYZER(1)NAME
llvm-bcanalyzer - LLVM bitcode analyzer
SYNOPSIS
llvm-bcanalyzer [options] [filename]
DESCRIPTION
The llvm-bcanalyzer command is a small utility for analyzing bitcode
files. The tool reads a bitcode file (such as generated with the
llvm-as tool) and produces a statistical report on the contents of the
bitcode file. The tool can also dump a low level but human readable
version of the bitcode file. This tool is probably not of much inter‐
est or utility except for those working directly with the bitcode file
format. Most LLVM users can just ignore this tool.
If filename is omitted or is -, then llvm-bcanalyzer reads its input
from standard input. This is useful for combining the tool into a
pipeline. Output is written to the standard output.
OPTIONS-nodetails
Causes llvm-bcanalyzer to abbreviate its output by writing out
only a module level summary. The details for individual func‐
tions are not displayed.
-dump Causes llvm-bcanalyzer to dump the bitcode in a human readable
format. This format is significantly different from LLVM assem‐
bly and provides details about the encoding of the bitcode file.
-verify
Causes llvm-bcanalyzer to verify the module produced by reading
the bitcode. This ensures that the statistics generated are
based on a consistent module.
-help Print a summary of command line options.
EXIT STATUS
If llvm-bcanalyzer succeeds, it will exit with 0. Otherwise, if an
error occurs, it will exit with a non-zero value, usually 1.
SUMMARY OUTPUT DEFINITIONS
The following items are always printed by llvm-bcanalyzer. They com‐
prize the summary output.
Bitcode Analysis Of Module
This just provides the name of the module for which bitcode analysis
is being generated.
Bitcode Version Number
The bitcode version (not LLVM version) of the file read by the ana‐
lyzer.
File Size
The size, in bytes, of the entire bitcode file.
Module Bytes
The size, in bytes, of the module block. Percentage is relative to
File Size.
Function Bytes
The size, in bytes, of all the function blocks. Percentage is rela‐
tive to File Size.
Global Types Bytes
The size, in bytes, of the Global Types Pool. Percentage is rela‐
tive to File Size. This is the size of the definitions of all types
in the bitcode file.
Constant Pool Bytes
The size, in bytes, of the Constant Pool Blocks Percentage is rela‐
tive to File Size.
Module Globals Bytes
Ths size, in bytes, of the Global Variable Definitions and their
initializers. Percentage is relative to File Size.
Instruction List Bytes
The size, in bytes, of all the instruction lists in all the func‐
tions. Percentage is relative to File Size. Note that this value
is also included in the Function Bytes.
Compaction Table Bytes
The size, in bytes, of all the compaction tables in all the func‐
tions. Percentage is relative to File Size. Note that this value
is also included in the Function Bytes.
Symbol Table Bytes
The size, in bytes, of all the symbol tables in all the functions.
Percentage is relative to File Size. Note that this value is also
included in the Function Bytes.
Dependent Libraries Bytes
The size, in bytes, of the list of dependent libraries in the mod‐
ule. Percentage is relative to File Size. Note that this value is
also included in the Module Global Bytes.
Number Of Bitcode Blocks
The total number of blocks of any kind in the bitcode file.
Number Of Functions
The total number of function definitions in the bitcode file.
Number Of Types
The total number of types defined in the Global Types Pool.
Number Of Constants
The total number of constants (of any type) defined in the Constant
Pool.
Number Of Basic Blocks
The total number of basic blocks defined in all functions in the
bitcode file.
Number Of Instructions
The total number of instructions defined in all functions in the
bitcode file.
Number Of Long Instructions
The total number of long instructions defined in all functions in
the bitcode file. Long instructions are those taking greater than 4
bytes. Typically long instructions are GetElementPtr with several
indices, PHI nodes, and calls to functions with large numbers of
arguments.
Number Of Operands
The total number of operands used in all instructions in the bitcode
file.
Number Of Compaction Tables
The total number of compaction tables in all functions in the bit‐
code file.
Number Of Symbol Tables
The total number of symbol tables in all functions in the bitcode
file.
Number Of Dependent Libs
The total number of dependent libraries found in the bitcode file.
Total Instruction Size
The total size of the instructions in all functions in the bitcode
file.
Average Instruction Size
The average number of bytes per instruction across all functions in
the bitcode file. This value is computed by dividing Total Instruc‐
tion Size by Number Of Instructions.
Maximum Type Slot Number
The maximum value used for a type’s slot number. Larger slot number
values take more bytes to encode.
Maximum Value Slot Number
The maximum value used for a value’s slot number. Larger slot num‐
ber values take more bytes to encode.
Bytes Per Value
The average size of a Value definition (of any type). This is com‐
puted by dividing File Size by the total number of values of any
type.
Bytes Per Global
The average size of a global definition (constants and global vari‐
ables).
Bytes Per Function
The average number of bytes per function definition. This is com‐
puted by dividing Function Bytes by Number Of Functions.
# of VBR 32-bit Integers
The total number of 32-bit integers encoded using the Variable Bit
Rate encoding scheme.
# of VBR 64-bit Integers
The total number of 64-bit integers encoded using the Variable Bit
Rate encoding scheme.
# of VBR Compressed Bytes
The total number of bytes consumed by the 32-bit and 64-bit integers
that use the Variable Bit Rate encoding scheme.
# of VBR Expanded Bytes
The total number of bytes that would have been consumed by the
32-bit and 64-bit integers had they not been compressed with the
Variable Bit Rage encoding scheme.
Bytes Saved With VBR
The total number of bytes saved by using the Variable Bit Rate
encoding scheme. The percentage is relative to # of VBR Expanded
Bytes.
DETAILED OUTPUT DEFINITIONS
The following definitions occur only if the -nodetails option was not
given. The detailed output provides additional information on a
per-function basis.
Type
The type signature of the function.
Byte Size
The total number of bytes in the function’s block.
Basic Blocks
The number of basic blocks defined by the function.
Instructions
The number of instructions defined by the function.
Long Instructions
The number of instructions using the long instruction format in the
function.
Operands
The number of operands used by all instructions in the function.
Instruction Size
The number of bytes consumed by instructions in the function.
Average Instruction Size
The average number of bytes consumed by the instructions in the
function. This value is computed by dividing Instruction Size by
Instructions.
Bytes Per Instruction
The average number of bytes used by the function per instruction.
This value is computed by dividing Byte Size by Instructions. Note
that this is not the same as Average Instruction Size. It computes
a number relative to the total function size not just the size of
the instruction list.
Number of VBR 32-bit Integers
The total number of 32-bit integers found in this function (for any
use).
Number of VBR 64-bit Integers
The total number of 64-bit integers found in this function (for any
use).
Number of VBR Compressed Bytes
The total number of bytes in this function consumed by the 32-bit
and 64-bit integers that use the Variable Bit Rate encoding scheme.
Number of VBR Expanded Bytes
The total number of bytes in this function that would have been con‐
sumed by the 32-bit and 64-bit integers had they not been compressed
with the Variable Bit Rate encoding scheme.
Bytes Saved With VBR
The total number of bytes saved in this function by using the Vari‐
able Bit Rate encoding scheme. The percentage is relative to # of
VBR Expanded Bytes.
SEE ALSO
/CommandGuide/llvm-dis, /BitCodeFormat
AUTHOR
Maintained by The LLVM Team (http://llvm.org/).
COPYRIGHT
2003-2017, LLVM Project
3.9 2017-12-22 LLVM-BCANALYZER(1)
