JPS59158460A - Structure memory recovery system - Google Patents

Abstract

PURPOSE:To improve the utilizing efficiency of a memory cell by dividing an area not in use into a heap and a relocate area and managing the system so that the heap area is used as a data section accumulating area of a new structure. CONSTITUTION:A heap memory 120 accumulates a data section of the structure to a continuous area and an area not in use of the memory 120 is divided into a heap area 121 and a relocate area 122. When the area 121 is used as a data accumulating area of the structure and the continuous area accumulating the data section of a new structure is not ensured, the data section 123 corresponding to the header section in use at present among the header section of the structure accumulated in the header memory 110 is relocated to the continuous area of the area 122 and the area including the area not in use of the areas 121 and 122 is taken as a new area 125 not in use. Then, the aea 125 is divided into the new heap and relocate areas, and the structure memory is managed 130 so that the heap area is used as the data section storage area of the structure produced newly.

Description

[Detailed description of the invention]

The present invention relates to a method for realizing a structure of a PIG and a method for recovering a mesori cell. In recent years, as interest in intelligent systems has increased, predicate logic m-language prologs have been attracting attention. One of the reasons for this is that it can handle structures composed of elements with variable values. For example, in the prolog, (apples), (none) in the basket. The structure person (basket) is the state in which (mandarin oranges) are contained. Using a structure with 3 elements, it can be expressed as follows. Basket (apples, pears, oranges) Furthermore, the fact that Abe has this basket can be expressed as follows using a structure with two elements:
(It can be written. Has (fat part, basket (apple, pear, orange)) In prolog, data can be easily written by using a structure with variable side elements like this.On the other hand, when executing prolog As a result, a large number of structures are dynamically created and destroyed, which requires a large amount of memory cells as the area for the structures.Therefore, in order to increase the efficiency of memory cell usage,
Once the used memory cells are collected, a so-called garbage conversion (hereinafter abbreviated as GC) is carried out to be used to realize a structure again. However, the processing cost associated with garbage collection is large, and may cost 30% to 50% or more of the entire processing cost. The present invention provides a method for realizing a structure that can process such garbage reflection at high speed. Before describing embodiments of the present invention, we would like to touch on the conventional methods of realizing structures and their problems (one of the well-known methods of realizing structures is to This method connects multiple items using a pointer. Figure 1 shows a conceptual diagram when expressing a structure (fat section, basket (apples, pears, oranges)) with a structure using the Vc binary list cell 10. The feature is that the unit for securing memory cells is a fixed length, so the unused area does not need to be in a continuous area.In other words,
The task of collecting used memory cells by garbage collection is simply to connect unnecessary fixed areas (two consecutive memory cells in a binary unlisted list) with a pointer. However, the method of connecting fixed-length areas with pointers has five problems, including the large overhead when accessing the elements of the structure. For example, in order to access the fourth element of the structure, the pointer must be traced externally, which causes a memory access bottleneck. As another method for solving the drawbacks of the above method, a method is known in which the elements of the structure are arranged in a continuous area and each element is accessed by offset from the header section. Figure 2 shows the structure (
It is a conceptual diagram expressing a basket (apples, pears, mandarin oranges). In Figure 2, 2° is the structure name area, 21
22 represents an element number area, 22 represents a structure header area, and 23 represents a data area. In this method, a structure has a structure header area 22 consisting of the structure name and the number of elements, and a data area 23 that stores each element of the structure, which are allocated as continuous areas.

[There is. Therefore, when a structure is included as an element, a pointer to the structure header area 22 may be used as the element. Furthermore, the elements can be accessed at high speed using the offset from the structure header area 22. However, this method has a problem in that the overhead of garbage collection is large. That is, in this method, the structure needs to be stored in a continuous area of variable length. Furthermore, due to the nature of structures, there is a possibility that one structure may be shared by a plurality of structures. Figure 3 (11, (21 is the structure great and structure C is structure B
FIG. 3 is a conceptual diagram showing the transition of a heap area due to garbage collection when shared. In Figure 3,
30 is heap memory, 31 is the area of the structure in use, 3
2 indicates the area of the used structure (5). Further, FIG. 3(1) shows the state of the heap memory before performing garbage collection, and FIG. 3(2) shows the state of the heap memory after performing garbage flexi. Garbage collection according to this method is realized as follows. First, mark the structure currently in use. This is accomplished by marking directly and indirectly referenced structures from the stack currently in use using the following algorithm. (1) Perform the process (2) for all structures pointed to by the stack. (2) If the structure is already marked as in use, do nothing; if not, mark the structure as in use, and if the structure further includes an Ic structure as an element; repeats the process (2) for all structures that are elements. Structures that are not marked as in use by the above algorithm can be reclaimed as used space. However, by simply connecting used areas with pointers (6) as in the structure implementation method using fixed areas, it is not possible to secure a continuous area as the area for the next new structure. Therefore, in order to secure an unused area on a continuous area, it is necessary to
As shown, the used structure area 31 must be evicted and the used area 32 must be collected. The problem with this method is that when relocating a structure, all pointers pointing to the relocated structure must be rewritten. An object of the present invention is to solve the problems of the conventional method described above, and to provide a structure that allows high-speed access to elements and minimizes the overhead of structure allocation during garbage flexion. The present invention provides a method for retrieving body memory. The purpose of the above is to create a header memory that stores the header portion of the structure for a structure consisting of a fixed-length header section that serves as an entry for the structure and a variable-length data section that stores each element of the structure. and a heap memory for storing the data portion of the structure in a continuous area; and an unused area of the heap memory is divided into a heap area and a storage area, and the heap area is used as the data portion storage area of the structure. During use, if a contiguous area to store the data part of a new structure runs out, the header part of the structure stored in the header memory corresponding to the header part currently in use is used. The data section to be relocated is relocated to a contiguous area of the relocate area, the combined area of the heap area and the unused area of the relocate area is set as a new unused area, and the unused area is newly combined with the heap area and the relocate area. This is achieved by a structure memory recovery method characterized by having a structure memory management unit that repeats the operation of dividing the heap area into 1'1m2 and using the heap area as a data storage area of a newly generated structure. be done. Next, specific examples of the present invention will be described. FIG. 4 is a block diagram of a structure memory recovery device which is one of the embodiments of the present invention. In the figure, 110 is a header memory, 111 is a mark bit storage area, 112 is a structure area, 113 is an element number area, and 114 is a pointer area to a data area for storing elements. Further, 120 is a heap memory, 121 is a heap area for storing the data part of the structure, and 122 is a storage area. moreover,
130 is a structure memory management unit; 131 is a 9p-digit area start address register indicating the start address of the relocate area 122; 132 is an unused area start address register indicating the start of the unused area of the heap area 121; 133 is an unused area end address register indicating the end of the unused area of the heap area 121. 150 is a stack memory that stores information used to execute prologs. And structure memory management unit 1
30 is the header memory 11o, the heap memory 12
Manage 0 and Stack Memo! J1501C represents a unit having the function of instructing marking of the structure currently in use from the pointer to the stored structure header, and 140 is the structure memory management unit)
130. It represents an internal bus that couples the stack memory 150 and an external processing unit (not shown). In this embodiment, the mark pit area 1111C2 bits, the structure hair area 1121C10 bits, and the element area 113K(
9) 8 bits are prepared, and 16 bits are prepared in the pointer area 114. Further, the header memory 110 has 9 KB, and the heap memory 120 has 128 KB out of 20 bits including the tag bit out of 4 bits. Therefore, in this embodiment, 2000 structures having a maximum of 256 elements can be handled. The structure memory management unit 130 is composed of, for example, a commercially available 16-bit microprocessor and a 4KB high-speed memory IC. Furthermore, the structure memory management unit 130 internally stores a relocate area start address register 131 and an unused area start address register 132.
, three 16-bit wide registers are provided as unused area end address registers 133. Stack memory 150 consists of 32 KB of 16 bit width memory. According to the present invention, all structures are accessed via the structure header, so the number of pointers pointing to the data area of the structure is at most one. Therefore, even if the data section is relocated, only the pointer section of the structure header needs to be rewritten, and the overhead of sp(10) can be greatly reduced. Further, since the structure header portion has a fixed length, a used structure header can be reused by simply adding a mark indicating an unused state. Furthermore, since the heap area is used by dividing the unused area into two, it is possible to utilize the entire heap area. Next, the structure memory recovery method in this embodiment will be explained with reference to the drawings. FIG. 5 is a conceptual diagram illustrating the structure memory recovery method in this embodiment. However, in this embodiment, the header with mark pit area 111 C00'' is an unused header, the header with rlO'+ is in use but the data part has never been relocated, and 711' is used. The header in which the data part is relocated is CO,'
1 represents a header whose data portion has been deleted once but is in a used state. When no structure is defined at all, the value of the mark pit area 111 of all structure headers is '001, and the relocate area start address register 131 stores the start address of the heap memory 120, and the unused area end address register 133 is heap memory 1
20, and the unused area start address register 132 is set to the address obtained by adding the address of the relocate area start address register 131 and the 7 addresses of the unused area end address register 133, and dividing the result by 2. . When the structure memory management unit 130 is requested to create a new structure from an external processing unit (for example, a prologue processor) not shown, the structure memory management unit 130 operates as follows. For example, consider creating a new structure basket (apples, pears, and oranges) on the heap. Introduction,
The number of elements 3 is added to the unused area start address register 132, and it is determined whether the value exceeds the value of the unused area end address register 133. If you haven't exceeded it, please write a header memo! J 110 mark pit area 111 is C00
), and select the structure name area 11 of the header.
2. Assign a value representing the structure name (basket), assign the number of elements (3) to the element number area 113, assign the address currently pointed to by the unused area start address register 132 to the pointer area 114, While incrementing the address of the unused area end address register 132 by 1, values representing the elements of the structure (apple), (none), and (orange) are stored in the heap memory 120, and the address of the header area is Returns K as the value of the structure to the external processing unit. As the value of the structure, the value of the structure header is returned as the address, so if the structure has (fat, basket (apple, apple,
A structure transparent body that includes a structure as an element, such as (none, orange)), stores a pointer to the structure header in the data area, as shown in FIG. FIG. 5 further shows that the structure baskets (Hanako, baskets (apples, pears, oranges)) share the structure basket (apples, pears, oranges), and the stack memory 150 has structures (fatty, baskets). (apple, pear, mandarin orange)) (13) represents a state in which only the structure (hanako, basket (apple, pear, mandarin orange)) is pointed to. In this situation, furthermore,
We will explain the behavior when adding structure humans (Atabe, Hanako). Similarly, the structure memory management unit 130 compares the value of the unused area start address register 132 plus the number of elements 2 with the value of the unused area end address register 133. If the value of the address register 133 is smaller, the garbage collection process described below is started. When the Car Hage Collection is activated, the values in the mark pit area 111 are first changed to 'oo, f',
05 is C005 +'11'+, rolt is C01)
Set to . Next, the structure headers in use are marked according to the following algorithm. (1) The process (2) is performed on each structure header stacked in the stack memory 1501C. (2) The value of the mark pit area of the structure header is (10)
(14) If C) or 11, do nothing. Coo) or '01
', set to '10) or '111 respectively,
Perform the process (3). (3) Move the data section of the heap memory 120 from the address pointed to by the void area 114 of the structure header to the element number head area 1.
13 values are searched, and the operation (2) is recursively repeated for elements whose value is the structure header. As a result, header memo! In Jll0IC, the mark pit of the structure header currently in use is set to area 111it or C11). Next, jJP casing of the data section 123 in use is performed according to the following algorithm. (]) Regarding the structure header whose value in the mark pit area 111 is C10'l in the header memory 110 (
After performing the process 2) and processing all structure headers, perform the process 3). (2) Locate the contents of the heap memory 120 from the address pointed to by the pointer area 114 of the structure header to the address plus the value of the number of elements field 110.Locate area from the address pointed to by the start address register 131 122 continuous area, and add the value of the element number head area 110 to the value of the new locate area start address register 132. (3) Relocate area start address register 131
The value obtained by adding the value of the unused area end address register 133 and the value of the unused area end address register 133 and dividing the value by 2 is set as the unused area starting address register 1.
Set it as a value of 32. FIG. 6 is a conceptual diagram showing the state of the heap memory after p-cage processing is performed using the above algorithm. Since the data area that was in the used state is compressed due to relocation, the remaining area 122 and the heap area 12 are relocated.
1 is obtained as a continuous region. In addition, the header memory 11
0, the value of the mark pit area 111 of the header of the structure whose data portion has been recovered is set to '00' KJi, so that the header area can be reused. After that, just add the structure to the newly created heap area as you would normally do. However, if the necessary data area and header area cannot be secured even after executing the SP cage, an error message is output and processing is interrupted. In this embodiment, since the data area that has been located once is not relocated again, the structure that is used after being located once is left in the heap memory 120. Such a structure is
The mark pit area has a header with a value of C01'' and can be recovered using the algorithm below. Assume that the relocation of the data area has now been completed. By the marking algorithm of the structure header, header memory 1] 0 structure header mark pit area 111
The value of is either COl or C1-. In this state, an algorithm for recovering the header and data part of the structure whose mark pit area 111 value is CO- will be described. (1) Among the headers whose mark pit area 111 has a value of C01'l in the header memory ll0VC, select the header whose address in the pointer area 114 is the smallest and set the value of the mark pit area 111 of that header to COO'l. Below, the address of the selected header is indicated by J. If no such header is found, terminate the process (17
) Finish. (2) Mark pit area 1 in header memory
Among the headers whose value is CI, pointer area 114
A header whose address is larger than J and has the smallest address among them is selected, and the process (3) is performed on the header. If no such header is found, the process ends; otherwise, the il+ process is repeated. (3) From the address of the heap memory 120 indicated by the pointer area 114 of the header, the number of elements in the header area 110
The data portion up to the address to which the value shown is added is relocated to a continuous area starting from address J, and address J is set in the pointer area 114. According to the above algorithm, the header and data part of the structure whose mark pit area 111 has a value of Co15 are removed, and a vacant area is created as a continuous area. For the start address of this empty area, select the header whose mark pit area is FLLS and the address of the pointer area 114 is the largest in the header memory 110, and (18) add the value of the number of elements area 113 of the header to the address. You can get it. Therefore, the start address of the free area is set in the relocate area start address register 131, and the start address of the empty area and the unused area end address register 1 are set in the unused area start address register.
Just set the value by adding the value of 33 and dividing by 2.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing an example of a structure realized using a fixed area, Figure 2 is a conceptual diagram showing an example of a structure realized using variable-length continuous areas, and Figure 3. (1),
(2) is a conceptual diagram showing an example of garbage flexicin when a structure is realized using a continuous region of variable length.
The figure is a block diagram of a structure memory recovery device which is an embodiment of the present invention. 5 and 6 are conceptual diagrams explaining the garbage collection system of the present invention. In the figure, 10 is a list cell, 20 is a structure hair area, 21 is an element number area, and 2
2 is the header area of the structure, 23c is the data area of the structure,
30 is heap memory, 31 is the area of the structure in use, 3
2 represents the area of the used structure. Further, 110 is a header memory of a structure processing device which is an embodiment of the present invention, 111 is a mark pit area, 112 is a structure hair area, 113 is an element number area, 114 is a pointer area to a data area, and 120 is a heap. Memory, 121 is a heap area, 122 is a space area, 123 is a data area in use, 124 is a used data area, 125 is an unused area, 130 is a structure memory management unit, 13
1 Spkate area light ff17 dress I/distor, 13
2 is an unused area start address register, 133 is an unused area end address register, 140 is an internal data bus,
150 represents a stack memory. Japanese Patent Publication No. 59-158460 (8)

Claims (1)

[Claims] For a structure composed of a fixed-length header part that becomes an entry of the structure and a variable-length data part that stores name elements of the structure, a header memory that stores the header part of the structure, and a header memory that stores the header part of the structure, and a header memory that stores the header part of the structure; When the heap memory is divided into a heap memory that stores the data part in a continuous area, and an unused area of the heap memory is divided into a heap area and a storage area, and the heap area is used as the data part storage area of the structure. k. When a continuous area for storing the data part of a new structure cannot be secured, the data part corresponding to the header part currently in use among the header parts of the structure stored in the header memory is stored in the IJR. leakage into a continuous region of the
Furthermore, the combined area of the heap area and the unused area of the p-cate area is set as a new unused area, and the unused area is newly divided into two, the heap area and the p-cate area, and the heap area is divided into two. A structure memory recovery method characterized by comprising a structure memory management unit that repeatedly uses the structure as a data storage area of a newly generated structure.