JPH047748A - Automatic array element assignment processing system based on reference order - Google Patents

Abstract

PURPOSE:To attain the effective use of a cache memory by assigning the array elements to the memory in accordance with the order in which an array is referred to in a program. CONSTITUTION:The reference order of array elements included in a loop in a source program 1 is analyzed by an array element reference order analysis processing means 5. Then the reference order information and the reference frequency are stored in an array element assignment information table 3. An array element assignment order decision processing means 6 decides the assignment order of array elements based on the table 3. Then a code generation processing means 7 outputs an object code 8 to refer to the array elements according to the decided assignment order. Therefore the array elements to be referred to for execution of the program 1 are continuously obtained in a cache memory. Then the effective use of the cache memory is attained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for allocating array elements of an array in a program, and in particular, an automatic reference order method for allocating array elements used in a loop to memory in the order in which they are referenced. Concerning array element allocation processing method.

[Conventional technology]

In conventional language processing systems, when array elements are allocated to an array area defined within a program, they are mechanically allocated according to a predetermined unique order, regardless of the reference order of the array elements. Figure 6 shows the three-dimensional array A.
An example of layout of array elements (100, 100, 100) according to the conventional method is shown. In this way, the standard allocation method for -Funetsuri is to allocate in the order that changes from the subscript of the lower dimension (the element on the right), and this is unique to the language processing system used for compilation. be.

[Problem to be solved by the invention]

However, the conventional array element allocation method has the following problems.

Since such arrays are executed intensively by instructions within a loop, they are normally referenced continuously. Therefore, when referring to array A in Figure 6, when executing a program in which a loop that changes the subscript of a lower dimension is inside a loop that changes the subscript of an upper dimension, the order in which it is allocated and the order in which it is referenced are different. Since it matches, especially between B
However, on the other hand, when executing a program in which a loop that changes the subscript of a higher dimension is inside a loop that changes the subscript of a lower dimension, the allocated order and the reference order do not match. Therefore, the next array element A (1, 1, 1) shown at 81 in the figure is the array element A (2, 1, IL) shown at S2, and the next is the array element A (3, 1, IL) shown at S3.
As in 1), the array will be referenced every 10,000 words. In this way, since the referenced memory address is far apart, it deviates from the range that is loaded into the cache memory, and the main memory is loaded frequently to the cache memory, which makes the point of having a cache memory go away. It will be lost. Furthermore, even if the array is large enough to be loaded into the cache memory at once, the object code becomes complicated and the program execution speed slows down because the memory cannot be referenced continuously.

The present invention has been made in view of the above-mentioned conventional problems,
By allocating array elements in memory in accordance with the order in which arrays are referenced in a program, the reference order allows for effective use of cache memory, simplification of generated object code, and increases program execution speed. The purpose is to provide an automatic array element allocation processing method using

[Means to solve the problem]

In order to achieve the above object, in the present invention, for an array defined in a source program, at least an array identifier that identifies the array and a reference order that identifies the order in which the array elements are referenced are provided. an array element allocation information table comprising information and the number of times the array is referenced; an array identifier registration processing means for registering the array identifier in the array element allocation information table; an array element reference order analysis processing means for analyzing the reference order of the array element and storing the information in the reference order information and the number of references in the array element allocation information table; array element allocation order determining processing means for determining the allocation order of array elements based on the array element allocation order determining processing means; and code generation processing means for outputting an object code that refers to the array elements in accordance with the order determined by the array element allocation order determining processing means. It is.

[For production]

Since the present invention is configured in this manner, the array element reference order analysis processing means analyzes the reference order of array elements in a loop in a source program and uses the reference order information and the number of references to allocate array elements. an object code that is stored in an information table, that an array element allocation order determination processing means determines the allocation order of array elements based on the array element allocation information table, and that a code generation processing means refers to the array elements according to the determined order; can be output.

(Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the method of the present invention. In Figure 1, ] is the source program to be compiled, 2 is the compiler, and 3 is the array identifier that identifies the array and the order in which the array elements are referenced for the array defined in the source program. 4 is an array identifier registration processing means for registering an array identifier in the array element allocation information table 3; 5 is an array element allocation information table consisting of reference order information for identifying the array and the number of times the array is referenced; Array element reference order analysis processing means 6 analyzes the reference order of the array element when it is referenced in the loop, and stores the information in the reference order information and reference count of the array element allocation information table 3; Array element allocation order determining processing means that determines the allocation order of array elements based on the array element allocation information table 3; 7 outputs an object code that refers to array elements in accordance with the order determined by the array element allocation order determining processing means; 8 is a generated object code.

Next, the operation of the above embodiment will be explained. Compiler 2 inputs source program 1 and generates object code 8.
In the process of outputting , the array identifier registration processing means 4 is called every time an array definition appears during syntactic or semantic analysis. The array identifier registration processing means 4 registers the array name as an array identifier in the array element allocation information table 3. If the array elements are referenced in the loop of the source program 1, the array element reference order analysis processing means 5 is called to check in what order the array elements are referenced by repeating the innermost loop. . If the subscripts of the lower dimension of the array are referenced in the order that they change first, then, for example, 1, and if the subscripts of the upper dimension are referenced in the order that they change first, then, for example, 2, It is added to the reference order information in the array element allocation information table 3 shown in FIG. 2, and 1 is added to the number of references. In the same figure, array a is referenced twice, both times indicating that the subscript of the higher dimension is referenced in the order that changes first, and array a is referenced three times, and each time the subscript of the lower dimension is referenced. indicates that they are referenced in the order in which they change first.

Similarly, array C is referenced once, indicating that the subscripts of higher dimensions are referenced in the order of change first.

Next, when the syntax analysis and semantic analysis are completed, the array element allocation order determining processing means 6 is called. The array element allocation order determination processing means 6 determines the allocation order of array elements based on the array element allocation information table 3 created as described above. That is, if the value obtained by dividing the reference order information in the array element allocation information table 3 by the number of references is less than 1.5, the reference order information is rewritten to 1, and if it is 1.5 or more, it is rewritten to 2. If there are many references in which the subscript of the lower dimension changes first for each array, the reference order information is determined to be 1, and in the opposite case, it is determined to be 2.

Figure 3 shows the result of executing array element allocation order determination processing for array element allocation information table 3 shown in Figure 2. Arrays a and array C are arranged in the order in which the subscript of the upper dimension changes first. are allocated in memory in the order in which sub-dimension subscripts change first. Next, the code generation processing means 7
is called and outputs an object code 8 that refers to array elements according to the reference order information of the array element allocation information table 3 determined by the array element allocation order determination processing means 6. That is, if the reference order information is 1, it is assumed that the array elements are allocated to the memory in the order in which the subscript of the lower dimension changes first, and the object code 8 that references the array elements is output. Similarly, if the reference order information is 2, it is assumed that the array elements are allocated to memory in the order in which the subscript of the higher dimension changes first, and an object code 8 that references the array elements is output.

Figure 4 shows an example of referencing two three-dimensional arrays A and B.
This is an example of an ORTRAN program, where array A is loop L
1, it is referenced sequentially from the subscript K of the lower dimension, and the array B
are referenced in the program L2 in order from the subscript K of the upper dimension.

FIG. 5 shows the allocation order of array elements when the FORTRAN program is processed according to the above embodiment, where array A is allocated so that the subscripts of the lower dimension can be referenced continuously, and array B is allocated so that the subscripts of the upper dimension can be referenced continuously. are allocated so that they can be referenced consecutively.

Therefore, according to the configuration of the embodiment as described above, array elements can be allocated to memory in the compilation unit of a source program in accordance with the order in which each array element is referenced in the program. Furthermore, if there are multiple references, array elements can be allocated in memory according to the order of reference most often.

〔Effect of the invention〕

According to the present invention, as is clear from the above-mentioned embodiments, the array elements referenced when executing the program are obtained consecutively on the memory, so that the cache memory can be used effectively. . In addition, since array elements are contiguous in memory, by using a post-increment instruction, there is no need to calculate the address of the next array element during repetition, and object needs for referencing array elements are simplified. This has the effect of increasing program execution speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the method of the present invention;
2 and 3 are explanatory diagrams showing the storage state of the array element allocation information table, FIG. 4 is an explanatory diagram showing the FORTRAN program list, FIG. 5 is an explanatory diagram showing the arrangement state of array elements according to the present invention, and FIG. FIG. 2 is an explanatory diagram showing an allocation state of array elements according to a conventional example. 1... Source program, 2... Compiler, 3...
- Array element allocation information table, 4... Array identifier registration processing means, 5... Array element reference order analysis processing means, 6
. . . Array element allocation order determination processing means; 7. Code generation processing means;

Claims (1)

[Claims] For an array defined in a source program, at least an array identifier that identifies the array, reference order information that identifies the order in which the array elements are referenced, and the number of times the array is referenced. an array element allocation information table consisting of; an array identifier registration processing means for registering the array identifier in the array element allocation information table; and when the array is referenced in a loop in a source program, the array element an array element reference order analysis processing means for analyzing the reference order of the array element allocation information table and storing the information in the reference order information and reference count of the array element allocation information table; An array element allocation order determining processing means for determining an array element allocation order, and a code generation processing means for outputting an object code that refers to array elements in accordance with the order determined by the array element allocation order determining processing means. Automatic array element allocation processing method.