4 { 5 register ulg c; 6 7 static ulg crc = (ulg)0xffffffffL; 8 9 if (s == NULL) { 10 c = 0xffffffffL; 11 } else { 12 c = crc; 13 if (n) do { 14 c = crc_32_tab[...]; 15 } while (--n); 16 } 17 crc = c; 18 return c ^ 0xffffffffL; 19 } `updcrc' has at least five basic-blocks. One is the function itself. The `if' statement on line 9 generates two more basic-blocks, one for each branch of the `if'. A fourth basic-block results from the `if' on line 13, and the contents of the `do' loop form the fifth basic-block. The compiler may also generate additional basic-blocks to handle various special cases. A program augmented for basic-block counting can be analyzed with `gprof -l -A'. The `-x' option is also helpful, to ensure that each line of code is labeled at least once. Here is `updcrc''s annotated source listing for a sample `gzip' run: ulg updcrc(s, n) uch *s; unsigned n; 2 ->{ register ulg c; static ulg crc = (ulg)0xffffffffL; 2 -> if (s == NULL) { 1 -> c = 0xffffffffL; 1 -> } else { 1 -> c = crc; 1 -> if (n) do { 26312 -> c = crc_32_tab[...]; 26312,1,26311 -> } while (--n); } 2 -> crc = c; 2 -> return c ^ 0xffffffffL; 2 ->} In this example, the function was called twice, passing once through each branch of the `if' statement. The body of the `do' loop was executed a total of 26312 times. Note how the `while' statement is annotated. It began execution 26312 times, once for each iteration through the loop. One of those times (the last time) it exited, while it branched back to the beginning of the loop 26311 times.  File: gprof.info, Node: Inaccuracy, Next: How do I?, Prev: Output, Up: Top 6 Inaccuracy of `gprof' Output ****************************** * Menu: * Sampling Error:: Statistical margins of error * Assumptions:: Estimating children times  File: gprof.info, Node: Sampling Error, Next: Assumptions, Up: Inaccuracy 6.1 Statistical Sampling Error ============================== The run-time figures that `gprof' gives you are based on a sampling process, so they are subject to statistical inaccuracy. If a function runs only a small amount of time, so that on the average the sampling process ought to catch that function in the act only once, there is a pretty good chance it will actually find that function zero times, or twice. By contrast, the number-of-calls and basic-block figures are derived by counting, not sampling. They are completely accurate and will not vary from run to run if your program is deterministic and single threaded. In multi-threaded applications, or single threaded applications that link with multi-threaded libraries, the counts are only deterministic if the counting function is thread-safe. (Note: beware that the mcount counting function in glibc is _not_ thread-safe). *Note Implementation of Profiling: Implementation. The "sampling period" that is printed at the beginning of the flat profile says how often samples are taken. The rule of thumb is that a run-time figure is accurate if it is considerably bigger than the sampling period. The actual amount of error can be predicted. For N samples, the _expected_ error is the square-root of N. For example, if the sampling period is 0.01 seconds and `foo''s run-time is 1 second, N is 100 samples (1 second/0.01 seconds), sqrt(N) is 10 samples, so the expected error in `foo''s run-time is 0.1 seconds (10*0.01 seconds), or ten percent of the observed value. Again, if the sampling period is 0.01 seconds and `bar''s run-time is 100 seconds, N is 10000 samples, sqrt(N) is 100 samples, so the expected error in `bar''s run-time is 1 second, or one percent of the observed value. It is likely to vary this much _on the average_ from one profiling run to the next. (_Sometimes_ it will vary more.) This does not mean that a small run-time figure is devoid of information. If the program's _total_ run-time is large, a small run-time for one function does tell you that that function used an insignificant fraction of the whole program's time. Usually this means it is not worth optimizing. One way to get more accuracy is to give your program more (but similar) input data so it will take longer. Another way is to combine the data from several runs, using the `-s' option of `gprof'. Here is how: 1. Run your program once. 2. Issue the command `mv gmon.out gmon.sum'. 3. Run your program again, the same as before. 4. Merge the new data in `gmon.out' into `gmon.sum' with this command: gprof -s EXECUTABLE-FILE gmon.out gmon.sum 5. Repeat the last two steps as often as you wish. 6. Analyze the cumulative data using this command: gprof EXECUTABLE-FILE gmon.sum > OUTPUT-FILE  File: gprof.info, Node: Assumptions, Prev: Sampling Error, Up: Inaccuracy 6.2 Estimating `children' Times =============================== Some of the figures in the call graph are estimates--for example, the `children' time values and all the time figures in caller and subroutine lines. There is no direct information about these measurements in the profile data itself. Instead, `gprof' estimates them by making an assumption about your program that might or might not be true. The assumption made is that the average time spent in each call to any function `foo' is not correlated with who called `foo'. If `foo' used 5 seconds in all, and 2/5 of the calls to `foo' came from `a', then `foo' contributes 2 seconds to `a''s `children' time, by assumption. This assumption is usually true enough, but for some programs it is far from true. Suppose that `foo' returns very quickly when its argument is zero; suppose that `a' always passes zero as an argument, while other callers of `foo' pass other arguments. In this program, all the time spent in `foo' is in the calls from callers other than `a'. But `gprof' has no way of knowing this; it will blindly and incorrectly charge 2 seconds of time in `foo' to the children of `a'. We hope some day to put more complete data into `gmon.out', so that this assumption is no longer needed, if we can figure out how. For the novice, the estimated figures are usually more useful than misleading.  File: gprof.info, Node: How do I?, Next: Incompatibilities, Prev: Inaccuracy, Up: Top 7 Answers to Common Questions ***************************** How can I get more exact information about hot spots in my program? Looking at the per-line call counts only tells part of the story. Because `gprof' can only report call times and counts by function, the best way to get finer-grained information on where the program is spending its time is to re-factor large functions into sequences of calls to smaller ones. Beware however that this can introduce artificial hot spots since compiling with `-pg' adds a significant overhead to function calls. An alternative solution is to use a non-intrusive profiler, e.g. oprofile. How do I find which lines in my program were executed the most times? Use the `gcov' program. How do I find which lines in my program called a particular function? Use `gprof -l' and lookup the function in the call graph. The callers will be broken down by function and line number. How do I analyze a program that runs for less than a second? Try using a shell script like this one: for i in `seq 1 100`; do fastprog mv gmon.out gmon.out.$i done gprof -s fastprog gmon.out.* gprof fastprog gmon.sum If your program is completely deterministic, all the call counts will be simple multiples of 100 (i.e., a function called once in each run will appear with a call count of 100).  File: gprof.info, Node: Incompatibilities, Next: Details, Prev: How do I?, Up: Top 8 Incompatibilities with Unix `gprof' ************************************* GNU `gprof' and Berkeley Unix `gprof' use the same data file `gmon.out', and provide essentially the same information. But there are a few differences. * GNU `gprof' uses a new, generalized file format with support for basic-block execution counts and non-realtime histograms. A magic cookie and version number allows `gprof' to easily identify new style files. Old BSD-style files can still be read. *Note Profiling Data File Format: File Format. * For a recursive function, Unix `gprof' lists the function as a parent and as a child, with a `calls' field that lists the number of recursive calls. GNU `gprof' omits these lines and puts the number of recursive calls in the primary line. * When a function is suppressed from the call graph with `-e', GNU `gprof' still lists it as a subroutine of functions that call it. * GNU `gprof' accepts the `-k' with its argument in the form `from/to', instead of `from to'. * In the annotated source listing, if there are multiple basic blocks on the same line, GNU `gprof' prints all of their counts, separated by commas. * The blurbs, field widths, and output formats are different. GNU `gprof' prints blurbs after the tables, so that you can see the tables without skipping the blurbs.  File: gprof.info, Node: Details, Next: GNU Free Documentation License, Prev: Incompatibilities, Up: Top 9 Details of Profiling ********************** * Menu: * Implementation:: How a program collects profiling information * File Format:: Format of `gmon.out' files * Internals:: `gprof''s internal operation * Debugging:: Using `gprof''s `-d' option  File: gprof.info, Node: Implementation, Next: File Format, Up: Details 9.1 Implementation of Profiling =============================== Profiling works by changing how every function in your program is compiled so that when it is called, it will stash away some information about where it was called from. From this, the profiler can figure out what function called it, and can count how many times it was called. This change is made by the compiler when your program is compiled with the `-pg' option, which causes every function to call `mcount' (or `_mcount', or `__mcount', depending on the OS and compiler) as one of its first operations. The `mcount' routine, included in the profiling library, is responsible for recording in an in-memory call graph table both its parent routine (the child) and its parent's parent. This is typically done by examining the stack frame to find both the address of the child, and the return address in the original parent. Since this is a very machine-dependent operation, `mcount' itself is typically a short assembly-language stub routine that extracts the required information, and then calls `__mcount_internal' (a normal C function) with two arguments--`frompc' and `selfpc'. `__mcount_internal' is responsible for maintaining the in-memory call graph, which records `frompc', `selfpc', and the number of times each of these call arcs was traversed. GCC Version 2 provides a magical function (`__builtin_return_address'), which allows a generic `mcount' function to extract the required information from the stack frame. However, on some architectures, most notably the SPARC, using this builtin can be very computationally expensive, and an assembly language version of `mcount' is used for performance reasons. Number-of-calls information for library routines is collected by using a special version of the C library. The programs in it are the same as in the usual C library, but they were compiled with `-pg'. If you link your program with `gcc ... -pg', it automatically uses the profiling version of the library. Profiling also involves watching your program as it runs, and keeping a histogram of where the program counter happens to be every now and then. Typically the program counter is looked at around 100 times per second of run time, but the exact frequency may vary from system to system. This is done is one of two ways. Most UNIX-like operating systems provide a `profil()' system call, which registers a memory array with the kernel, along with a scale factor that determines how the program's address space maps into the array. Typical scaling values cause every 2 to 8 bytes of address space to map into a single array slot. On every tick of the system clock (assuming the profiled program is running), the value of the program counter is examined and the corresponding slot in the memory array is incremented. Since this is done in the kernel, which had to interrupt the process anyway to handle the clock interrupt, very little additional system overhead is required. However, some operating systems, most notably Linux 2.0 (and earlier), do not provide a `profil()' system call. On such a system, arrangements are made for the kernel to periodically deliver a signal to the process (typically via `setitimer()'), which then performs the same operation of examining the program counter and incrementing a slot in the memory array. Since this method requires a signal to be delivered to user space every time a sample is taken, it uses considerably more overhead than kernel-based profiling. Also, due to the added delay required to deliver the signal, this method is less accurate as well. A special startup routine allocates memory for the histogram and either calls `profil()' or sets up a clock signal handler. This routine (`monstartup') can be invoked in several ways. On Linux systems, a special profiling startup file `gcrt0.o', which invokes `monstartup' before `main', is used instead of the default `crt0.o'. Use of this special startup file is one of the effects of using `gcc ... -pg' to link. On SPARC systems, no special startup files are used. Rather, the `mcount' routine, when it is invoked for the first time (typically when `main' is called), calls `monstartup'. If the compiler's `-a' option was used, basic-block counting is also enabled. Each object file is then compiled with a static array of counts, initially zero. In the executable code, every time a new basic-block begins (i.e., when an `if' statement appears), an extra instruction is inserted to increment the corresponding count in the array. At compile time, a paired array was constructed that recorded the starting address of each basic-block. Taken together, the two arrays record the starting address of every basic-block, along with the number of times it was executed. The profiling library also includes a function (`mcleanup') which is typically registered using `atexit()' to be called as the program exits, and is responsible for writing the file `gmon.out'. Profiling is turned off, various headers are output, and the histogram is written, followed by the call-graph arcs and the basic-block counts. The output from `gprof' gives no indication of parts of your program that are limited by I/O or swapping bandwidth. This is because samples of the program counter are taken at fixed intervals of the program's run time. Therefore, the time measurements in `gprof' output say nothing about time that your program was not running. For example, a part of the program that creates so much data that it cannot all fit in physical memory at once may run very slowly due to thrashing, but `gprof' will say it uses little time. On the other hand, sampling by run time has the advantage that the amount of load due to other users won't directly affect the output you get.  File: gprof.info, Node: File Format, Next: Internals, Prev: Implementation, Up: Details 9.2 Profiling Data File Format ============================== The old BSD-derived file format used for profile data does not contain a magic cookie that allows to check whether a data file really is a `gprof' file. Furthermore, it does not provide a version number, thus rendering changes to the file format almost impossible. GNU `gprof' uses a new file format that provides these features. For backward compatibility, GNU `gprof' continues to support the old BSD-derived format, but not all features are supported with it. For example, basic-block execution counts cannot be accommodated by the old file format. The new file format is defined in header file `gmon_out.h'. It consists of a header containing the magic cookie and a version number, as well as some spare bytes available for future extensions. All data in a profile data file is in the native format of the target for which the profile was collected. GNU `gprof' adapts automatically to the byte-order in use. In the new file format, the header is followed by a sequence of records. Currently, there are three different record types: histogram records, call-graph arc records, and basic-block execution count records. Each file can contain any number of each record type. When reading a file, GNU `gprof' will ensure records of the same type are compatible with each other and compute the union of all records. For example, for basic-block execution counts, the union is simply the sum of all execution counts for each basic-block. 9.2.1 Histogram Records ----------------------- Histogram records consist of a header that is followed by an array of bins. The header contains the text-segment range that the histogram spans, the size of the histogram in bytes (unlike in the old BSD format, this does not include the size of the header), the rate of the profiling clock, and the physical dimension that the bin counts represent after being scaled by the profiling clock rate. The physical dimension is specified in two parts: a long name of up to 15 characters and a single character abbreviation. For example, a histogram representing real-time would specify the long name as "seconds" and the abbreviation as "s". This feature is useful for architectures that support performance monitor hardware (which, fortunately, is becoming increasingly common). For example, under DEC OSF/1, the "uprofile" command can be used to produce a histogram of, say, instruction cache misses. In this case, the dimension in the histogram header could be set to "i-cache misses" and the abbreviation could be set to "1" (because it is simply a count, not a physical dimension). Also, the profiling rate would have to be set to 1 in this case. Histogram bins are 16-bit numbers and each bin represent an equal amount of text-space. For example, if the text-segment is one thousand bytes long and if there are ten bins in the histogram, each bin represents one hundred bytes. 9.2.2 Call-Graph Records ------------------------ Call-graph records have a format that is identical to the one used in the BSD-derived file format. It consists of an arc in the call graph and a count indicating the number of times the arc was traversed during program execution. Arcs are specified by a pair of addresses: the first must be within caller's function and the second must be within the callee's function. When performing profiling at the function level, these addresses can point anywhere within the respective function. However, when profiling at the line-level, it is better if the addresses are as close to the call-site/entry-point as possible. This will ensure that the line-level call-graph is able to identify exactly which line of source code performed calls to a function. 9.2.3 Basic-Block Execution Count Records ----------------------------------------- Basic-block execution count records consist of a header followed by a sequence of address/count pairs. The header simply specifies the length of the sequence. In an address/count pair, the address identifies a basic-block and the count specifies the number of times that basic-block was executed. Any address within the basic-address can be used.  File: gprof.info, Node: Internals, Next: Debugging, Prev: File Format, Up: Details 9.3 `gprof''s Internal Operation ================================ Like most programs, `gprof' begins by processing its options. During this stage, it may building its symspec list (`sym_ids.c:sym_id_add'), if options are specified which use symspecs. `gprof' maintains a single linked list of symspecs, which will eventually get turned into 12 symbol tables, organized into six include/exclude pairs--one pair each for the flat profile (INCL_FLAT/EXCL_FLAT), the call graph arcs (INCL_ARCS/EXCL_ARCS), printing in the call graph (INCL_GRAPH/EXCL_GRAPH), timing propagation in the call graph (INCL_TIME/EXCL_TIME), the annotated source listing (INCL_ANNO/EXCL_ANNO), and the execution count listing (INCL_EXEC/EXCL_EXEC). After option processing, `gprof' finishes building the symspec list by adding all the symspecs in `default_excluded_list' to the exclude lists EXCL_TIME and EXCL_GRAPH, and if line-by-line profiling is specified, EXCL_FLAT as well. These default excludes are not added to EXCL_ANNO, EXCL_ARCS, and EXCL_EXEC. Next, the BFD library is called to open the object file, verify that it is an object file, and read its symbol table (`core.c:core_init'), using `bfd_canonicalize_symtab' after mallocing an appropriately sized array of symbols. At this point, function mappings are read (if the `--file-ordering' option has been specified), and the core text space is read into memory (if the `-c' option was given). `gprof''s own symbol table, an array of Sym structures, is now built. This is done in one of two ways, by one of two routines, depending on whether line-by-line profiling (`-l' option) has been enabled. For normal profiling, the BFD canonical symbol table is scanned. For line-by-line profiling, every text space address is examined, and a new symbol table entry gets created every time the line number changes. In either case, two passes are made through the symbol table--one to count the size of the symbol table required, and the other to actually read the symbols. In between the two passes, a single array of type `Sym' is created of the appropriate length. Finally, `symtab.c:symtab_finalize' is called to sort the symbol table and remove duplicate entries (entries with the same memory address). The symbol table must be a contiguous array for two reasons. First, the `qsort' library function (which sorts an array) will be used to sort the symbol table. Also, the symbol lookup routine (`symtab.c:sym_lookup'), which finds symbols based on memory address, uses a binary search algorithm which requires the symbol table to be a sorted array. Function symbols are indicated with an `is_func' flag. Line number symbols have no special flags set. Additionally, a symbol can have an `is_static' flag to indicate that it is a local symbol. With the symbol table read, the symspecs can now be translated into Syms (`sym_ids.c:sym_id_parse'). Remember that a single symspec can match multiple symbols. An array of symbol tables (`syms') is created, each entry of which is a symbol table of Syms to be included or excluded from a particular listing. The master symbol table and the symspecs are examined by nested loops, and every symbol that matches a symspec is inserted into the appropriate syms table. This is done twice, once to count the size of each required symbol table, and again to build the tables, which have been malloced between passes. From now on, to determine whether a symbol is on an include or exclude symspec list, `gprof' simply uses its standard symbol lookup routine on the appropriate table in the `syms' array. Now the profile data file(s) themselves are read (`gmon_io.c:gmon_out_read'), first by checking for a new-style `gmon.out' header, then assuming this is an old-style BSD `gmon.out' if the magic number test failed. New-style histogram records are read by `hist.c:hist_read_rec'. For the first histogram record, allocate a memory array to hold all the bins, and read them in. When multiple profile data files (or files with multiple histogram records) are read, the memory ranges of each pair of histogram records must be either equal, or non-overlapping. For each pair of histogram records, the resolution (memory region size divided by the number of bins) must be the same. The time unit must be the same for all histogram records. If the above containts are met, all histograms for the same memory range are merged. As each call graph record is read (`call_graph.c:cg_read_rec'), the parent and child addresses are matched to symbol table entries, and a call graph arc is created by `cg_arcs.c:arc_add', unless the arc fails a symspec check against INCL_ARCS/EXCL_ARCS. As each arc is added, a linked list is maintained of the parent's child arcs, and of the child's parent arcs. Both the child's call count and the arc's call count are incremented by the record's call count. Basic-block records are read (`basic_blocks.c:bb_read_rec'), but only if line-by-line profiling has been selected. Each basic-block address is matched to a corresponding line symbol in the symbol table, and an entry made in the symbol's bb_addr and bb_calls arrays. Again, if multiple basic-block records are present for the same address, the call counts are cumulative. A gmon.sum file is dumped, if requested (`gmon_io.c:gmon_out_write'). If histograms were present in the data files, assign them to symbols (`hist.c:hist_assign_samples') by iterating over all the sample bins and assigning them to symbols. Since the symbol table is sorted in order of ascending memory addresses, we can simple follow along in the symbol table as we make our pass over the sample bins. This step includes a symspec check against INCL_FLAT/EXCL_FLAT. Depending on the histogram scale factor, a sample bin may span multiple symbols, in which case a fraction of the sample count is allocated to each symbol, proportional to the degree of overlap. This effect is rare for normal profiling, but overlaps are more common during line-by-line profiling, and can cause each of two adjacent lines to be credited with half a hit, for example. If call graph data is present, `cg_arcs.c:cg_assemble' is called. First, if `-c' was specified, a machine-dependent routine (`find_call') scans through each symbol's machine code, looking for subroutine call instructions, and adding them to the call graph with a zero call count. A topological sort is performed by depth-first numbering all the symbols (`cg_dfn.c:cg_dfn'), so that children are always numbered less than their parents, then making a array of pointers into the symbol table and sorting it into numerical order, which is reverse topological order (children appear before parents). Cycles are also detected at this point, all members of which are assigned the same topological number. Two passes are now made through this sorted array of symbol pointers. The first pass, from end to beginning (parents to children), computes the fraction of child time to propagate to each parent and a print flag. The print flag reflects symspec handling of INCL_GRAPH/EXCL_GRAPH, with a parent's include or exclude (print or no print) property being propagated to its children, unless they themselves explicitly appear in INCL_GRAPH or EXCL_GRAPH. A second pass, from beginning to end (children to parents) actually propagates the timings along the call graph, subject to a check against INCL_TIME/EXCL_TIME. With the print flag, fractions, and timings now stored in the symbol structures, the topological sort array is now discarded, and a new array of pointers is assembled, this time sorted by propagated time. Finally, print the various outputs the user requested, which is now fairly straightforward. The call graph (`cg_print.c:cg_print') and flat profile (`hist.c:hist_print') are regurgitations of values already computed. The annotated source listing (`basic_blocks.c:print_annotated_source') uses basic-block information, if present, to label each line of code with call counts, otherwise only the function call counts are presented. The function ordering code is marginally well documented in the source code itself (`cg_print.c'). Basically, the functions with the most use and the most parents are placed first, followed by other functions with the most use, followed by lower use functions, followed by unused functions at the end.  File: gprof.info, Node: Debugging, Prev: Internals, Up: Details 9.4 Debugging `gprof' ===================== If `gprof' was compiled with debugging enabled, the `-d' option triggers debugging output (to stdout) which can be helpful in understanding its operation. The debugging number specified is interpreted as a sum of the following options: 2 - Topological sort Monitor depth-first numbering of symbols during call graph analysis 4 - Cycles Shows symbols as they are identified as cycle heads 16 - Tallying As the call graph arcs are read, show each arc and how the total calls to each function are tallied 32 - Call graph arc sorting Details sorting individual parents/children within each call graph entry 64 - Reading histogram and call graph records Shows address ranges of histograms as they are read, and each call graph arc 128 - Symbol table Reading, classifying, and sorting the symbol table from the object file. For line-by-line profiling (`-l' option), also shows line numbers being assigned to memory addresses. 256 - Static call graph Trace operation of `-c' option 512 - Symbol table and arc table lookups Detail operation of lookup routines 1024 - Call graph propagation Shows how function times are propagated along the call graph 2048 - Basic-blocks Shows basic-block records as they are read from profile data (only meaningful with `-l' option) 4096 - Symspecs Shows symspec-to-symbol pattern matching operation 8192 - Annotate source Tracks operation of `-A' option  File: gprof.info, Node: GNU Free Documentation License, Prev: Details, Up: Top Appendix A GNU Free Documentation License ***************************************** Version 1.3, 3 November 2008 Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. `http://fsf.org/' Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 0. 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These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License. 2. VERBATIM COPYING You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3. You may also lend copies, under the same conditions stated above, and you may publicly display copies. 3. 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To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles. You may add a section Entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties--for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard. You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one. The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version. 5. COMBINING DOCUMENTS You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers. The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work. In the combination, you must combine any sections Entitled "History" in the various original documents, forming one section Entitled "History"; likewise combine any sections Entitled "Acknowledgements", and any sections Entitled "Dedications". You must delete all sections Entitled "Endorsements." 6. 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AGGREGATION WITH INDEPENDENT WORKS A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an "aggregate" if the copyright resulting from the compilation is not used to limit the legal rights of the compilation's users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document. If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document's Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate. 8. TRANSLATION Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail. If a section in the Document is Entitled "Acknowledgements", "Dedications", or "History", the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title. 9. TERMINATION You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License. However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation. Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice. Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it. 10. FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See `http://www.gnu.org/copyleft/'. Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Document. 11. RELICENSING "Massive Multiauthor Collaboration Site" (or "MMC Site") means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A "Massive Multiauthor Collaboration" (or "MMC") contained in the site means any set of copyrightable works thus published on the MMC site. "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization. "Incorporate" means to publish or republish a Document, in whole or in part, as part of another Document. An MMC is "eligible for relicensing" if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008. The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing. ADDENDUM: How to use this License for your documents ==================================================== To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page: Copyright (C) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with...Texts." line with this: with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.  Tag Table: Node: Top777 Node: Introduction2100 Node: Compiling4592 Node: Executing8648 Node: Invoking11436 Node: Output Options12851 Node: Analysis Options19940 Node: Miscellaneous Options23638 Node: Deprecated Options24893 Node: Symspecs26962 Node: Output28788 Node: Flat Profile29828 Node: Call Graph34781 Node: Primary38013 Node: Callers40601 Node: Subroutines42718 Node: Cycles44559 Node: Line-by-line51336 Node: Annotated Source55409 Node: Inaccuracy58408 Node: Sampling Error58666 Node: Assumptions61570 Node: How do I?63040 Node: Incompatibilities64594 Node: Details66088 Node: Implementation66481 Node: File Format72378 Node: Internals76668 Node: Debugging85163 Node: GNU Free Documentation License86764  End Tag Table This is binutils.info, produced by makeinfo version 4.8 from binutils.texi. Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". INFO-DIR-SECTION Software development START-INFO-DIR-ENTRY * Binutils: (binutils). The GNU binary utilities. END-INFO-DIR-ENTRY INFO-DIR-SECTION Individual utilities START-INFO-DIR-ENTRY * addr2line: (binutils)addr2line. Convert addresses to file and line. * ar: (binutils)ar. Create, modify, and extract from archives. * c++filt: (binutils)c++filt. Filter to demangle encoded C++ symbols. * cxxfilt: (binutils)c++filt. MS-DOS name for c++filt. * dlltool: (binutils)dlltool. Create files needed to build and use DLLs. * nlmconv: (binutils)nlmconv. Converts object code into an NLM. * nm: (binutils)nm. List symbols from object files. * objcopy: (binutils)objcopy. Copy and translate object files. * objdump: (binutils)objdump. Display information from object files. * ranlib: (binutils)ranlib. Generate index to archive contents. * readelf: (binutils)readelf. Display the contents of ELF format files. * size: (binutils)size. List section sizes and total size. * strings: (binutils)strings. List printable strings from files. * strip: (binutils)strip. Discard symbols. * elfedit: (binutils)elfedit. Update the ELF header of ELF files. * windmc: (binutils)windmc. Generator for Windows message resources. * windres: (binutils)windres. Manipulate Windows resources. END-INFO-DIR-ENTRY  File: binutils.info, Node: Top, Next: ar, Up: (dir) Introduction ************ This brief manual contains documentation for the GNU binary utilities (GNU Binutils) version 2.21: This document is distributed under the terms of the GNU Free Documentation License version 1.3. A copy of the license is included in the section entitled "GNU Free Documentation License". * Menu: * ar:: Create, modify, and extract from archives * nm:: List symbols from object files * objcopy:: Copy and translate object files * objdump:: Display information from object files * ranlib:: Generate index to archive contents * readelf:: Display the contents of ELF format files * size:: List section sizes and total size * strings:: List printable strings from files * strip:: Discard symbols * elfedit:: Update the ELF header of ELF files * c++filt:: Filter to demangle encoded C++ symbols * cxxfilt: c++filt. MS-DOS name for c++filt * addr2line:: Convert addresses to file and line * nlmconv:: Converts object code into an NLM * windres:: Manipulate Windows resources * windmc:: Generator for Windows message resources * dlltool:: Create files needed to build and use DLLs * Common Options:: Command-line options for all utilities * Selecting the Target System:: How these utilities determine the target * Reporting Bugs:: Reporting Bugs * GNU Free Documentation License:: GNU Free Documentation License * Binutils Index:: Binutils Index  File: binutils.info, Node: ar, Next: nm, Prev: Top, Up: Top 1 ar **** ar [`--plugin' NAME] [-]P[MOD [RELPOS] [COUNT]] ARCHIVE [MEMBER...] ar -M [