JPH031239A - Central processing unit - Google Patents

Abstract

PURPOSE:To evade unrequired recovery of a register and to prevent the register not being used at a call origin from being saved and recovered by executing the saving of the register at the call origin, executing the update of the register at a call destination, and furthermore, executing the recovery of the register at the call origin. CONSTITUTION:Register update information in which the presence/absence of the update of the content of the register is stored corresponding to each register is stored in an update information area 30. A register saving means 12 saves the current register update information to an external memory device 40 after saving the content of the register, and resets the register update information corresponding to a saved register. A register update information recording means 13 records the update of the register update information corresponding to an updated register. A register recovery means 14 recovers the content of the register having an update record to corresponding register update information out of designated registers, and resets the register update information corresponding to a recovered register. Thereby, it is possible to evade the unrequired recovery of the register.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a central processing unit of an information processing device. In particular, it relates to saving and restoring registers when a program is called in the target program.

〔overview〕

The present invention provides register update information for recording whether or not the contents of registers have been updated in a central processing unit, and when a register save instruction is executed to save registers by a caller when a program is called, registers that have been saved are The register update information corresponding to the register is reset, the register update information executed by the callee records the update of the register corresponding to the updated register, and the register recovery instruction executed by the caller records the update of the register. By restoring the contents of the registers whose updates are recorded in the corresponding register update information among the registers that need to be updated, it is possible to avoid restoring unnecessary registers.

[Conventional technology]

Conventionally, when saving registers when a program is called in a target program, the central processing unit saves the registers being used by the caller because there is no way to know the usage status of registers between the caller and the callee. or the registers used by the callee were saved and restored.

[Problems to be Solved by the Invention] However, in such conventional central processing units, when the caller saves and restores, the callee may save and restore registers that are not destroyed. In the method of saving and restoring first, registers that are not used by the caller may be saved and restored. As described above, since there is no means for the caller and the callee to mutually know the usage status of registers, there is a drawback that unnecessary registers are saved and restored.

SUMMARY OF THE INVENTION The present invention solves these conventional drawbacks, and aims to provide a central processing unit that can avoid unnecessary register recovery.

[Means for solving problems]

The present invention provides a plurality of registers for storing programs, a saving means for saving the contents of a specified register to an external storage device, and a recovery means for restoring the contents of the specified register with the corresponding contents of the storage device. and an instruction execution means including means for activating the saving means based on a register saving instruction and means for activating the recovery means based on a register restoring instruction, the central processing unit comprising: The instruction execution means includes an update information area for storing register update information for recording whether or not the contents have been updated, and an update recording means for recording updates in the register update information corresponding to the updated register. The saving means includes means for activating the update recording means based on an instruction, and the saving means saves the current register update information to the storage device after the save of the contents of the register is completed, and saves the register update information corresponding to the saved register. The recovery means includes a means for resetting, and the recovery means recovers the contents of a register that has an update record in the corresponding register update information among the registers specified by the register recovery instruction, and updates the register update information corresponding to the recovered register. It is characterized by including means for resetting.

[Effect]

Register update information for recording whether or not the contents of each register have been updated is stored in the update information area. The saving means activated based on the register saving instruction executed by the caller to save the register when the program is called saves the contents of the register 11! After completion, the current register update information is saved to an external storage device, and the register update information corresponding to the saved register is reset. The update recording means activated after the update is executed based on the register update instruction executed by the called party records the update in the register update information corresponding to the updated register. The recovery means activated based on the register recovery instruction executed by the caller recovers the contents of the specified register that has an update record in the corresponding register update information,
The register update information corresponding to this recovered register is reset. By the above operation, unnecessary register recovery can be avoided.

[Example] An example of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of a central processing unit according to an embodiment of the present invention, in which thick solid line arrows indicate activation relationships, and thin solid line arrows indicate reference setting relationships. In FIG. 1, the central processing unit includes a register group 20 including a plurality of registers for storing programs, and a register saving means 12 as a saving means for saving the contents of designated registers to an external storage device 40.
and a register recovery means 14 as a recovery means for recovering the contents of the specified register with the corresponding contents of the storage device 40.
and the register saving means 12 based on the register saving instruction.
and means for activating the register recovery means 14 based on the register recovery instruction.
1.

Here, the present invention is characterized by a register update information area 30 serving as an update information area for storing register update information that records whether or not the contents have been updated corresponding to each of the above-mentioned registers, and a register update information area 30 corresponding to the updated registers. The instruction execution means 11 includes means for activating the register update recording means 13 based on a register update instruction, and the instruction execution means 11 includes means for activating the register update recording means 13 based on a register update instruction. stores the current register update information in the storage device 4 after the register contents have been saved.
Register recovery means 1 includes means for saving register update information to 0 and resetting register update information corresponding to the saved register.
4 is to include means for restoring the contents of a register having an update record in the corresponding register update information among the registers specified by the register recovery instruction and resetting the register update information corresponding to the recovered register. .

The operation of the central processing unit having such a configuration will be explained. Second
The figure is a diagram showing the configuration and relationship between register groups and register update information areas of the central processing unit of the present invention. Third
The figure is a flowchart showing the operation of the central processing unit of the present invention.

In FIG. 2, 31. ．． 31□, , 31, is register 211, register 21□, , register 21. This is register update information for .

1 to 3, the central processing unit 10 activates the instruction execution means 11, and the instruction execution means 11 interprets the machine instruction (Sl). Upon execution of the register save instruction, the instruction execution means 11 activates the register save means 12 in step S2;
S3), and following the execution of the machine instruction to update the contents of the register, the instruction execution means 11 starts the register update recording means 13 (S2, S6), and furthermore, upon execution of the register recovery instruction, the instruction execution means 11 starts the register update recording means 13. , register recovery means 14
(S2, S8).

The register saving means 12 saves the registers specified by the register saving instruction and the contents of the register update information area 30 to the storage device 40 (S4), and resets the register update information corresponding to each specified register to "0". . That is, register 21. For register update information 31.
is reset to "0" (S5).

The register update recording means 13 records the updated register 21.
, and register update information 3t+ corresponding to register 21. , is set to "1". Records that the has been updated (S7
).

If it is recorded that the corresponding register update information has been updated among the registers specified by the register recovery instruction (S9), the register recovery means 14 recovers the contents of this register from the storage device 4o. ), otherwise (S9), the contents of this register are not changed and are not recovered (SIO). That is, register 21. If the register update information 31t is "1", recovery is performed.

Next, the logical sum of the contents of the register update information area 30 saved in the storage device 40 and the contents of the current register update information area 30 is calculated, and the result is set as the contents of the new register update information area 3G (512 ).

As described above, in this embodiment, the caller executes register saving, the callee executes register update, and the caller executes register recovery, thereby avoiding unnecessary register recovery. In addition, it is possible to prevent registers that are not used by the caller from being saved and restored.

〔Effect of the invention〕

As described above, the present invention has the excellent effect of avoiding unnecessary register recovery.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a central processing unit according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration and relationship between register groups and register update information areas of the central processing unit of the present invention. FIG. 3 is a flowchart showing the operation of the central processing unit of the present invention. 10...Central processing unit, 11...Instruction execution means, 1
2... Register saving means, 13... Register update recording means, 14... Register recovery means, 20... Register group, 21. ~21h...Register, 30...Register update information area, 31. ~31... Register update information, 40... Storage device.

Claims (1)

[Claims] 1. A plurality of registers for storing programs, a saving means for saving the contents of the specified register to an external storage device, and a saving means for saving the contents of the specified register with the corresponding contents of the storage device. In a central processing unit comprising a recovery means for recovering, and an instruction execution means including means for activating the saving means based on a register saving instruction and means for activating the recovery means based on a register recovery instruction, each of the above registers is provided. an update information area for storing register update information for recording whether or not the contents have been updated in response to the updated register; and update recording means for recording the update in the register update information corresponding to the updated register; includes means for activating the update recording means based on a register update instruction, and the saving means includes:
The recovery means includes means for saving the current register update information to the storage device and resetting the register update information corresponding to the saved register after the save of the contents of the register is completed; A central processing unit comprising means for restoring the contents of a register having an update record in corresponding register update information and resetting the register update information corresponding to the recovered register.