1=pod
2
3=head1 NAME
4
5llvm-bcanalyzer - LLVM bitcode analyzer
6
7=head1 SYNOPSIS
8
9B<llvm-bcanalyzer> [I<options>] [F<filename>]
10
11=head1 DESCRIPTION
12
13The B<llvm-bcanalyzer> command is a small utility for analyzing bitcode files.
14The tool reads a bitcode file (such as generated with the B<llvm-as> tool) and
15produces a statistical report on the contents of the bitcode file.  The tool
16can also dump a low level but human readable version of the bitcode file.
17This tool is probably not of much interest or utility except for those working
18directly with the bitcode file format. Most LLVM users can just ignore
19this tool.
20
21If F<filename> is omitted or is C<->, then B<llvm-bcanalyzer> reads its input
22from standard input. This is useful for combining the tool into a pipeline.
23Output is written to the standard output.
24
25=head1 OPTIONS
26
27=over
28
29=item B<-nodetails>
30
31Causes B<llvm-bcanalyzer> to abbreviate its output by writing out only a module
32level summary. The details for individual functions are not displayed.
33
34=item B<-dump>
35
36Causes B<llvm-bcanalyzer> to dump the bitcode in a human readable format. This
37format is significantly different from LLVM assembly and provides details about
38the encoding of the bitcode file.
39
40=item B<-verify>
41
42Causes B<llvm-bcanalyzer> to verify the module produced by reading the
43bitcode. This ensures that the statistics generated are based on a consistent
44module.
45
46=item B<-help>
47
48Print a summary of command line options.
49
50=back
51
52=head1 EXIT STATUS
53
54If B<llvm-bcanalyzer> succeeds, it will exit with 0.  Otherwise, if an error
55occurs, it will exit with a non-zero value, usually 1.
56
57=head1 SUMMARY OUTPUT DEFINITIONS
58
59The following items are always printed by llvm-bcanalyzer. They comprize the
60summary output.
61
62=over
63
64=item B<Bitcode Analysis Of Module>
65
66This just provides the name of the module for which bitcode analysis is being
67generated.
68
69=item B<Bitcode Version Number>
70
71The bitcode version (not LLVM version) of the file read by the analyzer.
72
73=item B<File Size>
74
75The size, in bytes, of the entire bitcode file.
76
77=item B<Module Bytes>
78
79The size, in bytes, of the module block. Percentage is relative to File Size.
80
81=item B<Function Bytes>
82
83The size, in bytes, of all the function blocks. Percentage is relative to File
84Size.
85
86=item B<Global Types Bytes>
87
88The size, in bytes, of the Global Types Pool. Percentage is relative to File
89Size. This is the size of the definitions of all types in the bitcode file.
90
91=item B<Constant Pool Bytes>
92
93The size, in bytes, of the Constant Pool Blocks Percentage is relative to File
94Size.
95
96=item B<Module Globals Bytes>
97
98Ths size, in bytes, of the Global Variable Definitions and their initializers.
99Percentage is relative to File Size.
100
101=item B<Instruction List Bytes>
102
103The size, in bytes, of all the instruction lists in all the functions.
104Percentage is relative to File Size. Note that this value is also included in
105the Function Bytes.
106
107=item B<Compaction Table Bytes>
108
109The size, in bytes, of all the compaction tables in all the functions.
110Percentage is relative to File Size. Note that this value is also included in
111the Function Bytes.
112
113=item B<Symbol Table Bytes>
114
115The size, in bytes, of all the symbol tables in all the functions. Percentage is
116relative to File Size. Note that this value is also included in the Function
117Bytes.
118
119=item B<Dependent Libraries Bytes>
120
121The size, in bytes, of the list of dependent libraries in the module. Percentage
122is relative to File Size. Note that this value is also included in the Module
123Global Bytes.
124
125=item B<Number Of Bitcode Blocks>
126
127The total number of blocks of any kind in the bitcode file.
128
129=item B<Number Of Functions>
130
131The total number of function definitions in the bitcode file.
132
133=item B<Number Of Types>
134
135The total number of types defined in the Global Types Pool.
136
137=item B<Number Of Constants>
138
139The total number of constants (of any type) defined in the Constant Pool.
140
141=item B<Number Of Basic Blocks>
142
143The total number of basic blocks defined in all functions in the bitcode file.
144
145=item B<Number Of Instructions>
146
147The total number of instructions defined in all functions in the bitcode file.
148
149=item B<Number Of Long Instructions>
150
151The total number of long instructions defined in all functions in the bitcode
152file. Long instructions are those taking greater than 4 bytes. Typically long
153instructions are GetElementPtr with several indices, PHI nodes, and calls to
154functions with large numbers of arguments.
155
156=item B<Number Of Operands>
157
158The total number of operands used in all instructions in the bitcode file.
159
160=item B<Number Of Compaction Tables>
161
162The total number of compaction tables in all functions in the bitcode file.
163
164=item B<Number Of Symbol Tables>
165
166The total number of symbol tables in all functions in the bitcode file.
167
168=item B<Number Of Dependent Libs>
169
170The total number of dependent libraries found in the bitcode file.
171
172=item B<Total Instruction Size>
173
174The total size of the instructions in all functions in the bitcode file.
175
176=item B<Average Instruction Size>
177
178The average number of bytes per instruction across all functions in the bitcode
179file. This value is computed by dividing Total Instruction Size by Number Of
180Instructions.
181
182=item B<Maximum Type Slot Number>
183
184The maximum value used for a type's slot number. Larger slot number values take
185more bytes to encode.
186
187=item B<Maximum Value Slot Number>
188
189The maximum value used for a value's slot number. Larger slot number values take
190more bytes to encode.
191
192=item B<Bytes Per Value>
193
194The average size of a Value definition (of any type). This is computed by
195dividing File Size by the total number of values of any type.
196
197=item B<Bytes Per Global>
198
199The average size of a global definition (constants and global variables).
200
201=item B<Bytes Per Function>
202
203The average number of bytes per function definition. This is computed by
204dividing Function Bytes by Number Of Functions.
205
206=item B<# of VBR 32-bit Integers>
207
208The total number of 32-bit integers encoded using the Variable Bit Rate
209encoding scheme.
210
211=item B<# of VBR 64-bit Integers>
212
213The total number of 64-bit integers encoded using the Variable Bit Rate encoding
214scheme.
215
216=item B<# of VBR Compressed Bytes>
217
218The total number of bytes consumed by the 32-bit and 64-bit integers that use
219the Variable Bit Rate encoding scheme.
220
221=item B<# of VBR Expanded Bytes>
222
223The total number of bytes that would have been consumed by the 32-bit and 64-bit
224integers had they not been compressed with the Variable Bit Rage encoding
225scheme.
226
227=item B<Bytes Saved With VBR>
228
229The total number of bytes saved by using the Variable Bit Rate encoding scheme.
230The percentage is relative to # of VBR Expanded Bytes.
231
232=back
233
234=head1 DETAILED OUTPUT DEFINITIONS
235
236The following definitions occur only if the -nodetails option was not given.
237The detailed output provides additional information on a per-function basis.
238
239=over
240
241=item B<Type>
242
243The type signature of the function.
244
245=item B<Byte Size>
246
247The total number of bytes in the function's block.
248
249=item B<Basic Blocks>
250
251The number of basic blocks defined by the function.
252
253=item B<Instructions>
254
255The number of instructions defined by the function.
256
257=item B<Long Instructions>
258
259The number of instructions using the long instruction format in the function.
260
261=item B<Operands>
262
263The number of operands used by all instructions in the function.
264
265=item B<Instruction Size>
266
267The number of bytes consumed by instructions in the function.
268
269=item B<Average Instruction Size>
270
271The average number of bytes consumed by the instructions in the function. This
272value is computed by dividing Instruction Size by Instructions.
273
274=item B<Bytes Per Instruction>
275
276The average number of bytes used by the function per instruction. This value is
277computed by dividing Byte Size by Instructions. Note that this is not the same
278as Average Instruction Size. It computes a number relative to the total function
279size not just the size of the instruction list.
280
281=item B<Number of VBR 32-bit Integers>
282
283The total number of 32-bit integers found in this function (for any use).
284
285=item B<Number of VBR 64-bit Integers>
286
287The total number of 64-bit integers found in this function (for any use).
288
289=item B<Number of VBR Compressed Bytes>
290
291The total number of bytes in this function consumed by the 32-bit and 64-bit
292integers that use the Variable Bit Rate encoding scheme.
293
294=item B<Number of VBR Expanded Bytes>
295
296The total number of bytes in this function that would have been consumed by
297the 32-bit and 64-bit integers had they not been compressed with the Variable
298Bit Rate encoding scheme.
299
300=item B<Bytes Saved With VBR>
301
302The total number of bytes saved in this function by using the Variable Bit
303Rate encoding scheme. The percentage is relative to # of VBR Expanded Bytes.
304
305=back
306
307=head1 SEE ALSO
308
309L<llvm-dis|llvm-dis>, L<http://llvm.org/docs/BitCodeFormat.html>
310
311=head1 AUTHORS
312
313Maintained by the LLVM Team (L<http://llvm.org/>).
314
315=cut
316