JPH11224185A - Device and method for analyzing variable influence - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable influence analyzing device capable of obtaining information useful to analyze the program by executing a certain degree of variable influence analyzing even when a program is a source program including more than two-stage pointers. SOLUTION: A variable information extracting means 10 reads the source program and extracts information concerning the depending relation of a variable. An influence analyzing method deciding means 11 decides the method for analyzing influence to be executed based on variable information which is obtained by the variable information extracting means 10. This device is provided with an influence analyzing means 12 for normally analyzing influence and a special variable analyzing means 13 for executing approximate analysis up to one stage for the source program which includes more than two-stage pointers. When it is judged that more than two-stage pointers are included by the influence analyzing method deciding means, approximate analysis is executed by the special variable analyzing means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reverse engineering of a general programming language system.
The present invention relates to a variable influence analysis device and a variable influence analysis method used when analyzing a source program.

[0002]

2. Description of the Related Art In an operation of analyzing and modifying an existing source program, there is a case where it is desired to modify only a part other than a certain variable and a part related to the variable without modifying it. Depending on the contents of the program, the variables may directly affect other parts of the program, or indirectly via parameters or the like, or as part of mathematical formulas. In such a case,
It is not immediately apparent what part of the program will be affected when you change the variable. Therefore, if the correction is made simply because the variable is not included, an unpredictable grammatical defect or the like may occur, and the program may not operate normally.

[0003] Therefore, in the analysis and correction of a source program, it is important to analyze the extent to which a variable is affected and which part is not affected in order to perform the analysis and correction efficiently. Become. As an apparatus for performing such an analysis, a variable influence analysis apparatus is known. This device reads a source program for which the influence of a variable is to be analyzed, extracts the variable information, and analyzes which variable affects which part in the program. Based on this dependency, you can know which variables affect which parts of the program. If the analysis / correction work is performed based on such information, the analysis / correction work can be made more efficient. The extraction of the variable information includes the extraction of information on data dependence and the extraction of information on control dependence.

[0004]

Among the data dependency analysis and the control dependency analysis performed by the conventional variable influence analysis apparatus, the analysis of the data dependency involves a problem that when the appearance of the variables becomes a little complicated, the Must be analyzed many times, which requires a huge amount of time and memory capacity. For example, in the case of the C language, when the number of pointers is two or more, the dependency to be analyzed increases exponentially, and the analysis time may become enormous, and the memory required for the analysis becomes enormous. Could be For this reason, in the conventional variable influence analysis device, a program having a data dependency such that the pointer has two or more stages is not accepted because it cannot be analyzed substantially.

However, a program to be actually analyzed often includes two or more stages of pointers, and there has been a demand for performing a variable influence analysis on such a program. The present invention has been made based on the above circumstances. Even if a source program includes two or more stages of pointers, a certain degree of variable influence analysis is performed to obtain information useful for analysis and correction work. It is an object of the present invention to provide an apparatus and a method for analyzing a variable influence.

[0006]

In order to solve the above-mentioned problems, a variable influence analysis device according to the present invention determines which part of a source program is affected by a variable included in a source program. In a variable influence analysis apparatus for analyzing, a variable information extraction unit for reading a source program to be analyzed and extracting information on data dependency of a variable, and performing a normal variable influence analysis on the source program. (1) variable influence analyzing means, (2) second variable influence analyzing means for performing an approximate variable effect analysis of a source program including two or more steps up to one step, and data extracted by the variable information extracting means. Based on the information on the dependency, it is determined whether or not the source program includes a pointer that is two or more steps ahead. If without the printer decides to perform variable impact analysis to the first variable effect analysis means, if it contains two or more stages of pointers second
And an influence analysis method determining means for determining that the variable influence analysis means performs the variable influence analysis.

A variable influence analysis method according to the present invention is an object of analysis in a variable influence analysis method for analyzing which part of a source program a variable included in a source program affects. A variable information extracting step of reading a source program and extracting information relating to data dependence of variables, a first variable influence analyzing step of performing a normal variable influence analysis on the source program, and two or more stages of pointers. Approximate variable effect analysis up to one stage for source program
Variable influence analysis step, based on the information on the data dependence extracted in the variable information extraction step, determine whether the source program includes a pointer two or more steps ahead, two or more pointers If not, it is determined that the variable influence analysis is performed in the first variable influence analysis step, and if two or more pointers are included, the variable influence analysis is performed in the second variable influence analysis step. And determining an influence analysis method.

[0008] A machine-readable recording medium according to the present invention provides a computer program having a variable influence analysis function for analyzing which part of a source program is affected by a variable included in the source program. In the recorded machine-readable recording medium,
A variable information extraction function of reading a source program to be analyzed and extracting information on data dependence of variables; a first variable influence analysis function of performing a normal variable influence analysis on the source program; A second variable influence analysis function for performing an approximate variable influence analysis on the source program including the above-described pointers up to one stage, and a second function based on information on data dependency extracted in the variable information extracting step. It is determined whether the source program includes a pointer that is two or more steps ahead. If the source program does not include a pointer that is two or more steps, it is determined that the variable influence analysis is performed in the first variable influence analysis step. An influence analysis method determining function for determining that a variable influence analysis is to be performed in the second variable influence analysis step when the pointer includes a plurality of stages or more; , Characterized in that it is recorded a computer program having a.

According to the present invention, even when the variable influence analysis determining means determines that the pointer includes two or more steps ahead based on the variable information extracted by the variable information extracting means, By the analysis means, an approximate analysis up to one stage is performed, and information useful for analysis / correction work can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, an outline of the variable influence analysis will be described. In the variable influence analysis, there are two analysis means based on data dependency and two analysis means based on control dependency, and the result of combining them is the result of the variable influence analysis.

Generally, in a program, defining a variable means that storage is allocated, and referring to a variable means using a stored value.
Also, the statement S2 is dependent on the statement S1 for data regarding the variable v means that the variable v is defined in the statement S1. The variable v is referred to in the statement S2.

There is an executable path from the statement S1 to the statement S2, which does not redefine the variable v. That is, the three conditions must be satisfied. Furthermore, the sentence S2
Is dependent on the statement S1. The statement S1 is a control branch point (if statement in C language, while statement
e).

Whether the statement S2 is executed depends directly on the execution result of the statement S1. That is, the two conditions must be satisfied. Next, the data dependency and the control dependency described above will be described using an actual program as an example. FIG. 1 is an example of a program written in C language. First, the program shown in the figure shows on the second line that the integer n is a value given from the outside. The fourth and fifth lines are declaration statements. The sixth line is an instruction to insert a value of 0 into the variable j, and the ninth line is an instruction to insert a value of 0 into the variable i.
The line is an instruction to put -1 into the variable i. Also, 8
Lines 10 and 10 have an if sentence. That is, if “n> 0” in the eighth line, the ninth line is executed, and if “n> 0”, the fourteenth line is executed. If “n> 0” and if “n <10” in the tenth row, the eleventh row is executed. Here, “++ j” on the eleventh line is an instruction to increment the value of the current variable j by one. After the above procedure, the value of the variable i at that time is returned on the 16th line.

The dependence of the variable j on the eleventh line of the program in FIG. 1 is considered separately for data dependence and control dependence. For this reason, looking back at the rows that affect the variable j, the 10th, 8th, 6th, and 2nd rows correspond to the rows that affect the variable j. Of these, the variable j is 10
The control depends on the line, the 10th line depends on the control on the 8th line, and the 8th line depends on the data on the 2nd line. Also, 1
It can be seen that the first row is data dependent on the sixth row.
Therefore, it can be understood that the program can be corrected without affecting the variable j if the line is other than these at the time of the analysis and correction work.

FIG. 2 shows another example of a program in C language. This program is similar to the program of FIG. 1, but is different from the program of FIG. 1 in the second, fifth, sixth, eleventh, and sixteenth rows. In the program of FIG. 2, “** (variable)” on the second, fifth, eleventh, and sixteenth lines indicates a pointer two steps ahead of the variable, that is, a pointer to the pointer. For example, the instruction “++ (** j)” on line 11 is
"Add 1 to the value of the point ahead of j, that is, the value of j two steps ahead,
Put it back here. ". That is, it is first necessary to check where the value j is pointing. Once we know the * j to which j points, we must then find out where the value of * j points. When ** j to which * j points is known, finally, the value of ** j is checked, 1 is added thereto, and an operation of re-entering the obtained value is performed.

FIG. 3 is a diagram schematically showing such a situation. That is, j indicates * j, and * j is **
j. However, there are many cases where j points, and there are many cases where * j points. Therefore, when the number of pointers is two or more, the possibility to be examined is rapidly increased, and the time required for analysis and the memory capacity used are enormous. For this reason, it has been practically impossible with a conventional variable influence analyzer to analyze data dependence in a program including such two or more stages of pointers.

On the other hand, in the variable influence analysis apparatus according to the present embodiment, the data dependency of a program including such two or more stages of pointers is not immediately analyzed but not completely analyzed. Nevertheless, it does some analysis to try to derive some insight into data dependencies. That is, when it is determined that the pointer includes two or more steps ahead, the analysis is performed only on the pointer for one step and the result is output.

FIG. 4 is a block diagram of the variable influence analysis apparatus according to the present embodiment. This apparatus reads a source program and analyzes which variable in the program affects which part in the program, for both data dependency and control dependency. Variable analysis results can be obtained by combining the results of each analysis. Note that, among the two analyses, the analysis of the control dependency relationship can be used as it is in the related art, so that the description thereof will be omitted here, and the analysis of the data dependency relationship will be described.

In FIG. 1, first, variable information extracting means 1
0 reads a source program and extracts information on data dependency of variables. In other words, "in which statement the variable v is defined" or "in which statement the variable v
Is referenced ".
Based on the variable information obtained by the variable information extracting means 10, the influence analyzing method determining means 11 determines whether or not there are two or more stages of pointers in the source program to be analyzed, and determines whether the variable effect analyzing means 12 or It functions to determine which of the special variable influence analysis means 13 to use for analysis. The variable influence analysis means 12 performs normal data dependence analysis, and the special variable influence analysis means 13 analyzes a source program including two or more stages of pointers up to one stage of pointers. is there.

That is, the analysis is performed by the special variable influence analysis means 13 only when there are two or more pointers in the source program to be analyzed, and otherwise, the normal analysis is performed by the variable influence analysis means 12. . The analysis result is obtained as a variable influence analysis result by being combined with a control dependent analysis result (not shown). As described above, the variable influence analysis device of the present embodiment includes the influence analysis method determination means 11 and the special variable influence analysis means 13, so that two or more stages of pointers which were conventionally determined to be impossible to analyze can be obtained. Simple analysis can now be performed on included source programs.

FIG. 5 is a flowchart showing the operation of the variable influence analyzer according to the present embodiment. Step S10
In step (1), a source code of a program to be subjected to a variable influence analysis is read into a variable influence analysis device. Step S
At 11, variable information is extracted from the source program. In step S12, based on the extracted variable information, it is determined whether the pointer of the variable included in the extracted variable information is one stage or less, or two or more stages. Here, when the pointer of the variable is one level or less, a normal variable influence analysis is performed in step S13. On the other hand, in step S12, the pointer of the variable is changed, for example, as in the program shown in FIG.
If it is determined that there are two or more steps, step S1
In step 4, instead of performing the variable influence analysis on all of the pointers, an approximate variable influence analysis is performed only in one step, and a certain answer is obtained. In this case, the fact is displayed on a CRT or the like as necessary in order to inform the operator that an approximate analysis of only one stage has been performed.

Although the answer obtained in this manner is not an accurate analysis result, it is sufficiently useful for performing a debugging operation. If the debugging operation is performed based on the result, the efficiency of the debugging operation can be improved. Can be planned. The present invention is not limited to the above embodiment, and various changes can be made within the scope of the gist. Since each means of the variable influence analysis device of the present invention can be realized by software operating on a computer, the software for performing the above operation is recorded on a recording medium such as a CD-ROM, and the software is read by a computer. By doing so, it is possible to use the computer as a variable influence analysis device.

[0023]

As described above, according to the present invention,
Even if the variable influence analysis determining means determines that the pointer includes two or more steps ahead based on the variable information extracted by the variable information extracting means, the second variable influence analyzing means may perform an approximate Since the analysis is performed, a variable effect analysis is performed while approximating a source program that includes a pointer beyond two or more steps, which was practically impossible to analyze due to the huge amount of analysis in the past, and information useful for debugging work is provided. can get. As a result, it is possible to provide a variable influence analysis device and a variable influence analysis method capable of improving the efficiency of debugging work.

[Brief description of the drawings]

FIG. 1 is a diagram showing an actual example of a source program for performing a variable influence analysis.

FIG. 2 is a diagram showing another example of a source program for performing a variable influence analysis.

FIG. 3 is a diagram schematically showing that the time required to analyze a pointer in two or more stages becomes enormous.

FIG. 4 is a block diagram of a variable influence analysis device according to the present embodiment.

FIG. 5 is a flowchart showing an operation of the variable influence analysis device according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Variable information extraction means 11 Impact analysis method determination means 12 Impact analysis means 13 Special variable influence analysis means

Claims (9)

[Claims] 1. A variable influence analysis apparatus for analyzing what effect a variable included in a source program has on which part of the source program, reads a source program to be analyzed, and stores data of the variable. Variable information extracting means for extracting information on a dependency, first variable influence analyzing means for performing a normal variable influence analysis on the source program, and up to one step for a source program including two or more stages of pointers A second variable influence analysis means for performing an approximate variable influence analysis of: based on the information on the data dependency extracted by the variable information extraction means, whether or not the source program includes a pointer two or more steps ahead; Is determined, and if the pointer does not include two or more stages, the first variable influence analysis means performs the variable influence analysis. Effect analysis method determining means for determining that the second variable influence analysis means performs the variable influence analysis when including a pointer of two or more stages. Impact analysis device. 2. The variable influence analysis apparatus according to claim 1, wherein when the second variable influence analysis means performs the variable influence analysis, the fact is displayed. 3. The method according to claim 1, wherein the variable information extracting means further extracts information on a control dependency.
Or the variable influence analyzer according to 2. 4. A variable influence analysis method for analyzing how a variable included in a source program affects which part of the source program, reads a source program to be analyzed, and stores data of the variable. A variable information extracting step of extracting information relating to a dependency, a first variable influence analyzing step of performing a normal variable influence analysis on the source program, and a first step for a source program including two or more stages of pointers A second variable influence analysis step of performing an approximate variable influence analysis, and whether or not the source program includes a pointer two or more steps ahead based on the information on the data dependency extracted in the variable information extraction step. Is determined, and if the pointer does not include two or more steps, the variable shadow is determined in the first variable influence analysis step. Determining to perform the analysis, and when including two or more stages of pointers, an impact analysis method determining step of deciding to perform the variable impact analysis in the second variable impact analysis step. Variable impact analysis method to be performed. 5. The variable influence analysis method according to claim 4, wherein, when the variable influence analysis is performed in the second variable influence analysis step, the fact is displayed. 6. The variable influence analysis method according to claim 4, wherein in the variable information extracting step, information on a control dependency is further extracted. 7. A machine-readable recording medium on which a computer program having a variable influence analysis function for analyzing which part of a source program has a variable included in a source program is analyzed, A variable information extraction function for reading a source program to be analyzed and extracting information on data dependence of variables; a first variable influence analysis function for performing a normal variable influence analysis on the source program; A second variable influence analysis function for performing an approximate variable influence analysis of the source program including the above-mentioned pointers up to one stage, based on the information on the data dependency extracted in the variable information extraction step, Determines whether the source program contains a pointer that is two or more steps ahead. When no inter is included, it is determined that the variable influence analysis is performed in the first variable influence analysis step. When two or more pointers are included, the variable influence analysis is performed in the second variable influence analysis step. And a function for deciding an impact analysis method for deciding that a computer program is recorded. 8. The variable influence analysis method according to claim 7, wherein when the variable influence analysis is performed by the second variable influence analysis function, the effect is displayed. 9. The variable influence analysis method according to claim 7, wherein said variable information extraction function further has a function of extracting information relating to control dependencies.