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 llvmas 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
interest 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 functions are
not displayed.
-dump: Causes llvm-bcanalyzer to dump the bitcode in a human readable format. This format is significantly different from LLVM assembly
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
comprize 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
analyzer.
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
relative to File Size.
Global Types Bytes: The size, in bytes, of the Global Types Pool. Percentage is
relative 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
relative 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
functions. 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
functions. 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
module. 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
bitcode 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
Instruction 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
number values take more bytes to encode.
Bytes Per Value: The average size of a Value definition (of any type). This is
computed 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
variables).
Bytes Per Function: The average number of bytes per function definition. This is
computed 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 perfunction 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
funtion. 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
consumed 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
Variable Bit Rate encoding scheme. The percentage is relative to # of VBR Expanded Bytes.

AUTHORS

Maintained by the LLVM Team (<http://llvm.org>).

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