Compressing detected current and preceding instructions with the same operation code and operand patterns

Abstract

A processor accesses memory storing a compressed instruction sequence that includes compression information indicating that an instruction that with respect to the preceding instruction, has identical operation code and operand continuity is compressed. The processor includes a fetcher that fetches a bit string from the memory and determines whether the bit string is a non-compressed instruction, where if so, transfers the given bit string and if not, transfers the compression information; and a decoder that upon receiving the non-compressed instruction, holds in a buffer, instruction code and an operand pattern of the non-compressed instruction and executes processing to set to an initial value, the value of an instruction counter that indicates a count of consecutive instructions having identical operation code and operand continuity, and upon receiving the compression information, restores the instruction code based on the instruction code held in the buffer, the instruction counter value, and the operand pattern.

What is claimed is: 
     
         1 . A processor having access to a memory storing therein a sequence of compressed instruction groups including compression information indicating that an instruction having operation code identical to that of the preceding instruction and having operand continuity with the preceding instruction has been compressed, the processor comprising:
 a fetcher that fetches a given bit string from the memory and judges a combination pattern of the compression information in the given bit string and a non-compressed instruction, where concerning a non-compressed instruction, further identifies the non-compressed instruction in the given bit string and transfers the non-compressed instruction, and concerning the compression information, further transfers the compression information, and   a decoder that upon receiving the non-compressed instruction transferred thereto from the fetcher, holds in a buffer, instruction code and an operand pattern of the non-compressed instruction and executes setting processing of setting to an initial value, the value of an instruction counter that indicates a consecutive count of consecutive instructions having identical operation code and operands with regularity, and upon receiving the compression information transferred thereto from the fetcher, restores the instruction code based on the instruction code held in the buffer, the value of the instruction counter, and the operand pattern.   
     
     
         2 . A computer-readable medium storing therein a compression program that causes a computer to execute a process, the process comprising:
 acquiring a test subject from an instruction group under test that is among a sequence of instruction groups;   determining whether operation code of the acquired test subject and operation code of a preceding instruction are identical, and whether operands of the test subject and operands of the preceding instruction have continuity, the preceding instruction being an instruction at a position that corresponds to that of the test subject, in the instruction group that precedes the instruction group under test; and   compressing the test subject when at the determining identicalness and continuity are determined.   
     
     
         3 . The computer-readable medium according to  claim 2 , wherein
 the compressing, when identicalness and continuity are determined, includes appending to the test subject, compression information indicating that the test subject is compressed, and deleting the operation code and the operands of the test subject.   
     
     
         4 . The computer-readable medium according to  claim 2 , the process further comprising
 setting for the test subject, compression information indicating that the test subject is not compressed and storage information indicating that the test subject is an instruction that is to be stored, the setting being performed when identicalness and continuity are not determined at the determining.   
     
     
         5 . The computer-readable medium according to  claim 4 , wherein
 the determining, when identicalness and continuity are not determined, includes determining whether the test subject is to be stored, based on the operation code type of the test subject, and   the setting, when storage is determined, includes setting for the test subject, the compression information indicating that the test subject is not compressed and the storage information indicating that the test subject is an instruction that is to be stored, and when storage is not determined, includes setting for the test subject, compression information indicating that the test subject is not compressed and the storage information indicating that the test subject is not an instruction that is to be stored.   
     
     
         6 . The computer-readable medium according to  claim 2 , the process further comprising
 storing a compression information group obtained from test subjects of the instruction group under test, and subsequent to the compression information group, storing a non-compressed test subject that is in the instruction group under test, is not compressed, and for which the storage information has been set.   
     
     
         7 . The computer-readable medium according to  claim 6 , wherein
 the storing includes shortening by concatenating storage results obtained for each instruction group under test.   
     
     
         8 . A compression apparatus comprising:
 an acquirer that acquires a test subject from an instruction group under test that is among a sequence of instruction groups;   a determiner that determines whether operation code of the acquired test subject and operation code of a preceding instruction are identical, and whether operands of the test subject and operands of the preceding instruction have continuity, the preceding instruction being an instruction at a position that corresponds to the that of the test subject, in the instruction group that precedes the instruction group under test; and   a compressor that compresses the test subject when identicalness and continuity are determined by the determiner.   
     
     
         9 . A compression method executed by a computer, the compression method comprising:
 acquiring a test subject from an instruction group under test that is among a sequence of instruction groups;   determining whether operation code of the acquired test subject and operation code of a preceding instruction are identical, and whether operands of the test subject and operands of the preceding instruction have continuity, the preceding instruction being an instruction at a position that corresponds to that of the test subject, in the instruction group that precedes the instruction group under test; and   compressing the test subject when at the determining identicalness and continuity are determined.