JPH01187640A - Unset area detection system - Google Patents

Abstract

PURPOSE:To effectively detect an unset error without imposing a burden on execution speed at normal time by detecting the unsetting of a value by interruption. CONSTITUTION:In a storage device 1 with an existing error detecting mechanism, an instruction SIV 8 to write a pattern which is decided to be unjustifiable by said detecting mechanism is newly provided, and further, a function to generate the interruption of low urgency for an arithmetic unit 2 when this unjustifiable pattern is read is provided. Accordingly, in case the area where the value is not yet set is referred, the purport of its is detected by the interruption. Further, the mechanism which considers the unjustifiable pattern to be a specified thing and suppresses an abnormal interruption by said unjustifiable pattern for the storage device 1 is provided. Thus, the unset error can be detected effectively without imposing burden at the time of normal execution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an execution system for computer languages, and particularly to data stored in a storage device and high-speed, high-reliability operations thereof.

[Conventional technology]

For the area reserved in the computer's storage device.

A method of checking whether a value has been set has been required for a long time, but there was no suitable means for efficiently implementing it.

A typical example of a means for determining whether or not a value has been set in a certain address area by providing an additional mechanism using hardware is the use of a tag pit. E, Transactions on Computers C22 Number 7, (
1973) pp. 644-656 (I EEE,
Trans.

Computers, C-22, No. 7 (
1973) +pp, 644-656).

The method for software detection is to set a specific pattern as an "undefined value", initialize the memory acid with that pattern at the start of program execution, and compare it with the "undefined value" in advance for subsequent references. There are things to be inspected. (For example, VO82/VO33Pa5ca1
etc.) [Problems to be solved by the invention] The method of adding a hardware mechanism such as tag pit changes the structure of the storage device, and it is difficult to install that mechanism in computers that are currently widely used. It's not easy to get into it. Furthermore, although the method of performing comparison with an "undefined value" pattern using software can reduce the number of comparisons by analyzing the source program, the cost required for the determination is not small. Further, there is a problem that a specific pattern cannot be used, and that patterns cannot be unified due to differences in byte/word types. moreover,
Judgment is necessary even if the program is executed normally, and this checking is usually suppressed once the program has finished testing and entered the production stage. For this reason, there is a considerable possibility that detection will not be possible even if detection is truly desired.

As described above, the conventional technology has a problem in that it cannot be performed on current computers with a small amount of changes and without overhead.

The purpose of the present invention is to set/unset values in the storage device area,
The goal is to achieve this using a method that has little impact on current models and also causes almost no burden during normal execution.

[Means for solving problems]

In the present invention, a new instruction is provided to write a pattern that is determined to be invalid by the current error detection mechanism in a storage device having an error detection mechanism, and furthermore, when this invalid pattern is read, an emergency message is sent to the arithmetic unit. By providing a function that generates a low-level interrupt, there is no burden during normal execution, and when an area with an unset value is referenced, this is detected by an interrupt.

Furthermore, a mechanism is provided for specifying an invalid pattern and suppressing an interruption of the storage device abnormality caused by the invalid pattern. If the unset value is not to be detected, this can also be done by suppressing the above-mentioned interrupt.

[Effect]

When the illegal pattern stored in the storage device is read out when the program is executed by the new instruction in the present invention,
This causes an interrupt. When the arithmetic unit detects this interrupt, it performs a predetermined process to deal with the unset error. If such a situation does not occur and the program is being executed normally, there is no need for any software inspection, and the execution speed will not be reduced.

In this way, it is possible to effectively detect unconfigured errors without putting a burden on the normal execution speed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail. A program is written as a collection of subprograms, and the object code of each subprogram first executes a series of instructions to set its own environment before its execution. In FIG. 1, when control is passed to subprogram P, P's environment setting instruction sequence E secures an area for local variables used by P.

Since this area is to be detected as an unset value, it is initialized with the invalid pattern using the new instruction 5IV of 8 (FIG. 2).

In this embodiment, this invalid pattern is considered to be one that requires a parity check for a storage device in which a parity pit is added for every pie 1 to 1. After initialization, the output programs are executed sequentially as usual. It is possible that part of L will receive values set as it executes, while the rest will remain unset. In such a state, when the instruction 7X (○PA, B), which performs an operation by referring to the unset area, and the operand A is in the unset area in L, is executed, an invalid pattern is detected and an interrupt is generated. Notify the arithmetic unit with the signal No. 9. In this example, since a parity check is generated, the arithmetic unit transfers control to the user program R (in this case, a runtime routine generated by a compiler) in the same manner as normal interrupt processing.

As described above, if it is detected that the setting is not set, the process can be easily performed. Furthermore, if the reference area has had its value set in advance, the process proceeds in exactly the same way as normal processing.

The SIV instruction has the structure shown in Figure 2, with an operation code (10), length (11), and effective address (12).
It consists of three fields. This starts from the effective address and initializes an area of length specified by the length field with an invalid pattern.

Furthermore, since interruptions caused by this illegal pattern can be suppressed in the middle of the program, detection and non-detection of unset values can be performed more effectively.

〔Effect of the invention〕

According to the present invention, unset values can be detected by adding a small amount of hardware, and the present invention has the following effects compared to conventional methods.

(1) Detection is done by interrupt, so it is fast.

(2) For a normal operation in which the reference location is already set, there is no detection overhead, and extra time is required only to initialize the local variable area.

(3) All it takes is a slight change in the storage device and the addition of one instruction.
Can be easily applied to existing machines.

(4) There is no need to create a dangerous execution environment in which checks are performed during testing but not during actual operation, which is the case with many conventional programs.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is an explanatory diagram describing a storage device, an arithmetic unit, initial settings, and detection of non-settings, and FIG. 2 is a format diagram of a newly installed instruction for setting an invalid pattern. 1...Storage device, 2...Arithmetic unit, 3...Local variable area, 4-6...Code, 8...Newly installed instruction.

Claims (1)

[Claims] 1. An information processing device comprising an arithmetic unit and a storage device operated by the arithmetic unit, characterized in that the storage device has a mechanism for checking the validity of retained data for each addressing unit. By providing an instruction for storing a pattern detected as invalid by a validity detection mechanism from an arithmetic unit at an arbitrary address of the storage device, and a processing means for detecting the invalid pattern,
An unset area detection method characterized in that when data in a storage device is referenced during program execution, if the contents are unset, a detection mechanism of the storage device detects the content.