NAME

atom_application_instrumentation, AddCallProto, AddCallProgram, AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, ReplaceProto, ReplaceEntry, ReplaceProcedure − Allows an Atom tool’s instrumentation routine to add, within an application program, calls to analysis routines

SYNOPSIS

#include <cmplrs/atom.inst.h>
void AddCallProto(
        const char ∗ ); void AddCallProgram(
        PlaceType,
        const char ∗, ... ); void AddCallObj(
        Obj ∗,
        PlaceType,
        const char ∗, ... ); void AddCallProc(
        Proc ∗,
        PlaceType,
        const char ∗, ... ); void AddCallEntry(
        Entry ∗,
        PlaceType,
        const char ∗, ... ); void AddCallBlock(
        Block ∗,
        PlaceType,
        const char ∗, ... ); void AddCallInst(
        Inst ∗,
        PlaceType,
        const char ∗, ... ); void ReplaceProto(
        const char ∗ ); void ReplaceEntry(
        Entry ∗,
        const char ∗, ... ); void ReplaceProcedure(
        Proc ∗,
        const char ∗ );

DESCRIPTION

The Atom application instrumentation routines allow you to add arbitrary procedure calls before and after objects, procedures, basic blocks, and instructions.  You can also add procedure calls before a main or alternate entry point. In addition, you can add procedure calls before and after the application program executes. 

You can use these routines only from an Atom tool’s instrumentation file. See atom(1) for a description of Atom. 

AddCallProto Routine

You must use the AddCallProto routine to specify the prototype of each procedure call to be added to the program. In other words, an AddCallProto call must define the procedural interface for each call to an analysis procedure to be added to the program by subsequent calls to AddCallProgram, AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, and AddCallInst. 

The format of the prototype is similar to a C language function definition.  The name of the analysis procedure is followed by a parenthesized list of arguments. 

There are four basic argument types:

       •Constants

       •Computed values (VALUE)

       •Register values (REGV and FREGV)

       •Address translation structure (∗XLATE)

Constant types include char, int, long, char ∗, char[], int[], and long[]. Often, arrays are used to communicate static information, especially large data structures, to analysis procedures. Three special keywords exist to facilitate the passing of array and string arguments:

const
Indicates that the analysis routine cannot modify or write to the passed array or string. Atom allocates the memory for such a string or array in the instrumented program’s read-only memory. Using const can thus greatly reduce the memory usage of instrumented programs that have multiple images active simultaneously. 

stable
Indicates that Atom does not need to make a copy of the data for the string or array during instrumentation. If your instrumentation code passes a stable buffer to AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, or AddCallInst, it must not modify or free the buffer until after WriteObj is called for the object containing the given Obj, Proc, Entry, Block, or Inst. If you pass a stable buffer to AddCallProgram, you must never modify or free the buffer. 

Strings returned by the following routines can be considered stable for the duration of the instrumentation process: GetObjName, GetObjOutName, GetAnalName, GetObjInstArray, ProcName, ProcFileName, and GetInstProcCalled. 

freeIndicates that Atom does not need to make a copy of the data for the string or array during instrumentation and that it will deallocate the buffer (by calling free) when it is done with it. Instrumentation code should never modify or free such a buffer after it has been passed to AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, or AddCallProgram. 

You can use the const keyword with either stable or free. The stable and free keywords are mutually exclusive. 

The VALUE argument type defines an argument with a 64-bit value that Atom must compute before passing it to the analysis procedure.  There are two arguments of the VALUE argument type, as listed in the following table. For such arguments, specify VALUE in the AddCallProto call and the argument’s symbolic name in the call to AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, or AddCallProgram. 

The REGV and FREGV argument types define an argument representing the contents of a register.  FREGV is used for floating-point registers; REGV is used for all other registers. There are several arguments of the REGV and FREGV argument types, as listed in the following table. For such arguments, specify REGV or FREGV in the AddCallProto call and the argument’s symbolic name in the call to AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, or AddCallProgram. 

Note that the special REGV-type value REG_NOTUSED is also defined as a return value from GetInstRegEnum. You cannot pass it as an argument to AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, AddCallInst, or AddCallProgram. 

Note

When you use AddCallObj, you will sometimes find that the analysis routine for each added call requires a slightly different prototype. This usually occurs when you pass an array argument and the number of elements in the array depends on the contents of the object. Normally, it is illegal to reprototype an analysis routine, but Atom makes an exception for array parameters. If the only difference between the new prototype and the old prototype is the length of an array parameter, Atom allows you to use AddCallProto to reprototype the analysis routine.  Subsequent calls to that analysis routine will use the new array length. 

AddCallProgram Routine

Use the AddCallProgram routine in an InstrumentInit or InstrumentAll routine to add a call to an analysis procedure before a program starts execution or after it completes execution. Typically such an analysis procedure does something that applies to the whole program, such as opening an output file or parsing command line options. Supply a PlaceType value of ProgramBefore or ProgramAfter as the instrumentation point, followed by the name of the analysis procedure and a list of its arguments.  Since ProgramAfter actions are executed after the program is complete, library routines requiring system services should not be used in ProgramAfter analysis routines. 

Because the Instrument routine is called for each object in a program, avoid calling AddCallProgram from the Instrument routine. 

If the program forks and ProgramBefore is specified, Atom calls the analysis procedure only once - before the parent process starts execution. If ProgramAfter is specified, Atom calls the analysis procedure after each child process completes execution and after the parent process completes execution. 

AddCallObj Routine

Use the AddCallObj routine in an instrumentation routine to add a call to an analysis procedure before an object starts execution or after it completes execution. Typically such an analysis procedure does something that applies to the single object, such as initializing some data for its procedures. Supply a PlaceType value of ObjBefore or ObjAfter as the instrumentation point, followed by the name of the analysis procedure and a list of its arguments. 

Instrumentation code added at the beginning of an object is executed immediately after the object is loaded into memory (before any procedures in that object are executed). Instrumentation code added at the end of an object is executed immediately before that object is unloaded from memory (after all procedures from that object have finished execution). 

Note

An InstrumentAll routine must call the BuildObj routine before calling AddCallObj, AddCallProc, AddCallEntry, AddCallBlock, or AddCallInst to add analysis routine calls, and before traversing the procedures in the object.  BuildObj builds the internal data structures Atom uses to manipulate the object. After the Atom tool traverses and instruments the object, the InstrumentAll routine must call the WriteObj routine to write out the instrumented version of the object. See the atom_object_management(5) reference page for additional information. 

AddCallProc Routine

Use the AddCallProc routine in an instrumentation routine to add a call to an analysis procedure before a procedure starts execution or after it completes execution. Supply a PlaceType value of ProcBefore or ProcAfter as the instrumentation point, followed by the name of the analysis procedure and a list of its arguments.  The following factors determine when the analysis procedures are called:

       •If the procedure has multiple entry points and ProcBefore is specified, Atom calls the analysis procedure at each entry point. 

       •If the procedure has multiple exit points and ProcAfter is specified, Atom calls the analysis procedure each time it issues a return. If the procedure contains interprocedural branches or interprocedural jumps, the call to the analysis procedure will occur before the branch or jump. Compilers can optimize return statements or non-returning function calls to interprocedural branches. To avoid this, recompile with -O0 or -no_inline. 

       •If the procedure does not issue a return (for example, it calls exit or longjmp), Atom does not call the analysis procedure. 

AddCallEntry Routine

Use the AddCallEntry routine in an instrumentation routine to add a call to an analysis routine before a main or alternate entry starts execution. Supply a PlaceType value of EntryBefore as the instrumentation point, followed by the name of the analysis procedure and a list of its arguments. 

AddCallBlock Routine

Use the AddCallBlock routine in an instrumentation routine to add a call to an analysis procedure before a basic block starts execution or after it completes execution. Supply a PlaceType value of BlockBefore or BlockAfter as the instrumentation point, followed by the name of the analysis procedure and a list of its arguments. 

If the basic block ends with an unconditional branch or jump and BlockAfter is specified, Atom calls the analysis procedure after the basic block completes execution. However, if the basic block ends with a jump to a subroutine that does not return (for instance, the subroutine calls exit or longjmp), Atom does not call the analysis procedure. 

AddCallInst Routine

Use the AddCallInst routine in an instrumentation routine to add a call to an analysis procedure before a given instruction executes or after it executes. Supply a PlaceType value of InstBefore or InstAfter as the instrumentation point, followed by the name of the analysis procedure and a list of its arguments. 

If the instruction is an unconditional branch or jump and InstAfter is specified, Atom calls the analysis procedure after the instruction executes. However, if the instruction is a jump to a subroutine that does not return (for example, the subroutine calls exit or longjmp), Atom does not call the analysis procedure. 

PlaceType Hierarchy

An implied PlaceType hierarchy exists in the execution ordering of calls to analysis procedures when the calls occur at the same instrumentation point. By enforcing an ordering, Atom guarantees, for instance, that a call to an analysis procedure added at BlockBefore executes before a call to an analysis procedure added at InstBefore when the Inst and the Block identify the same instrumentation point. 

The before PlaceType ordering of calls is:

ProgramBefore
ObjBefore
ProcBefore or EntryBefore
BlockBefore
InstBefore

The after PlaceType ordering of calls is:

InstAfter
BlockAfter
ProcAfter
ObjAfter
ProgramAfter

Multiple calls added at the same instrumentation point via the same PlaceType will be executed in the order they were instrumented.  Multiple calls added at the same instrumentation point via the ProcBefore and EntryBefore PlaceTypes will also be executed in the order they were instrumented since the ProcBefore and EntryBefore PlaceTypes have the same before PlaceType ordering. 

ReplaceEntry Routine

Use the ReplaceEntry routine to intercept an application’s calls to a given main or alternate entry point. Only calls that follow the Alpha Calling Standard can be intercepted, and calls that have been expanded inline by compiler optimizations cannot be intercepted. 

The char ∗ argument indicates the name of the replacement procedure in the tool’s analysis code that will be called instead of the replaced entry point. Only the specified entry point is replaced; other entry points in the same procedure may be replaced by using additional ReplaceEntry calls. 

In addition to performing the desired analysis, the replacement procedure should emulate the replaced entry point by accepting all the same arguments and returning a comparable return value. Replacement procedures usually implement this emulation by calling the replaced entry point through a function pointer that is either passed into the replacement procedure as the ReplAddrValue argument (see below) or is initialized by calling the XlateAddr routine with an address translation buffer set up via the AddXlateEntry routine. 

Note that replacing entry points containing thread cancellation points is not supported. 

The tool’s instrumentation code must call the ReplaceProto routine first, in the same way that the AddCallProto routine must be called before the AddCallProc routine.  ReplaceProto must be called before the main executable is written. 

ReplaceProto Routine

You must use the ReplaceProto routine to declare the procedural interface to any replacement procedure before making the associated ReplaceEntry call.  ReplaceProto’s single string pointer argument has the same format as that of AddCallProto.  ReplaceProto accepts a superset of AddCallProto’s procedural interface arguments, to allow application and analysis data to be passed into the replacement procedure. 

The following two additional arguments can be used to provide the replacement procedure with the application arguments and the address of the replaced entry point. These arguments have VALUE argument types and are similar to those supported by the AddCallProto routine. Note that currently only fixed arguments are supported, not "..." variable argument lists. 

For example, the following pair of ReplaceProto and ReplaceEntry calls intercepts calloc(3) library calls, passing two application arguments and three additional analysis arguments (the return address of the application’s call to calloc, the replaced library routine’s run-time address, and the ObjID of the object that contains calloc). 

ReplaceProto("replacement_calloc(VALUE, VALUE, REGV, VALUE, long)");
ReplaceEntry(FindEntry(obj,"calloc"), "replacement_calloc",
             ArgValue, ArgValue, REG_RA, ReplAddrValue,
             GetObjInfo(obj,ObjID));

The associated replacement routine would be declared like this:

int replacement_calloc(size_t num, size_t size, long ra,
                       void ∗(∗replaced_calloc)(size_t, size_t),
                       long obj_id);

ReplaceProcedure Routine

Use the ReplaceProcedure routine to replace a procedure with a routine that has the same arguments and return type but is linked with your analysis code. The named replacement code should emulate the replaced procedure, and it will usually also analyze all the calls made to it by applications.  Any alternate entry points are also replaced and are assumed to have the same arguments and return type. 

The ReplaceProcedure routine does not support replacing undocumented library routines, and it does not support replacement routines that are optimized in certain ways. It is retained for compatibility with earlier releases, but using ReplaceEntry (above) is recommended. 

EXAMPLES

The following example accumulates wall-clock and per-process time for a procedure. The instrumentation routine defines the prototypes for calls to analysis procedures and identifies the instrumentation points at which those calls take place:

   AddCallProto("Start(REGV)");
   AddCallProto("Stop(REGV)");
   .
   .
   .
   AddCallProc(p,ProcBefore,"Start",REG_CC);
   AddCallProc(p,ProcAfter,"Stop",REG_CC);
   .
   .
   .

The analysis routine is complicated by the format of the cycle counter. The low-order 32 bits contain a free running cycle count.  The high-order 32 bits of the counter are an offset that, when added to the low-order 32 bits, produces a cycle count for this process. The low-order 32 bits can be used directly to determine wall clock times:

   long total;
   long process;
   int ccStart;
   int ccStartProcess;
   void Start(unsigned long cc) {
     ccStart = cc;
     ccStartProcess = ((cc << 32) + cc) >> 32;
   }
   void Stop(unsigned long cc) {
     int ccEnd = cc;
     int ccEndProcess = ((cc << 32) + cc) >> 32;
     total += (unsigned) (ccEnd - ccStart);
     process += (unsigned) (ccEndProcess - ccStartProcess);
   }

RETURN VALUES

These routines have no return values. 

FILES

/usr/include/cmplrs/atom.inst.h
Header file containing external definitions of Atom routines

SEE ALSO

Commands: atom(1)

Functions: atom_application_navigation(5), atom_application_query(5), atom_application_symbols(5), atom_description_file(5), atom_instrumentation_routines(5), atom_object_management(5), AnalHeapBase(5), Thread(5), Xlate(5)

Programmer’s Guide