Techniques for instruction group formation for decode-time instruction optimization based on feedback

Patent metadata

Field	Value
Publication number	US-9733940-B2
Application number	US-201414543533-A
Country	US
Kind code	B2
Filing date	Nov 17, 2014
Priority date	Nov 17, 2014
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A technique of processing instructions for execution by a processor includes determining whether a first property of a first instruction and a second property of a second instruction are compatible. The first instruction and the second instruction are grouped in an instruction group in response to the first and second properties being compatible and a feedback value generated by a feedback function indicating the instruction group has been historically beneficial with respect to a benefit metric of the processor. Group formation for the first and second instructions is performed according to another criteria, in response to the first and second properties being incompatible or the feedback value indicating the grouping of the first and second instructions has not been historically beneficial.

First claim

What is claimed is:

1. A processor, comprising:
a processor core; and
a memory coupled to the processor core, wherein the processor core is configured to:
determine whether a first property of a first instruction and a second property of a second instruction in an instruction stream are compatible, wherein the first instruction is a last instruction before a cache boundary and the second instruction is an initial instruction after the cache boundary;
group the first instruction and the second instruction in a same decode-time instruction optimization group in response to the first and second properties being compatible and a feedback value generated by a feedback function indicating the same decode-time instruction optimization group has been historically beneficial with respect to a benefit metric of the processor; and
group the first and second instructions in different decode-time instruction optimization groups in response to the first and second properties being compatible and the feedback value indicating the grouping of the first and second instructions in the same decode-time instruction optimization group has not been historically beneficial.

2. The processor of claim 1 , wherein the another criteria corresponds to maximizing a number of instructions in instruction groups or minimizing instruction groups.

3. The processor of claim 1 , wherein the first and second properties are associated with instruction classes and/or instruction registers.

4. The processor of claim 3 , wherein the instruction classes are represented by a single bit or multiple bits.

5. A data processing system, comprising:
a processor; and
a memory coupled to the processor, wherein the processor is configured to:
determine whether a first property of a first instruction and a second property of a second instruction in an instruction stream are compatible, wherein the first instruction is a last instruction before a cache boundary and the second instruction is an initial instruction after the cache boundary;
group the first instruction and the second instruction in a same decode-time instruction optimization group in response to the first and second properties being compatible and a feedback value generated by a feedback function indicating the same decode-time instruction optimization group has been historically beneficial with respect to a benefit metric of the processor; and
group the first and second instructions in different decode-time instruction optimization groups in response to the first and second properties being compatible and the feedback value indicating the grouping of the first and second instructions in the same decode-time instruction optimization group has not been historically beneficial.

6. The data processing system of claim 5 , wherein the another criteria corresponds to maximizing a number of instructions in instruction groups or minimizing instruction groups.

7. The data processing system of claim 5 , and wherein the first and second properties are associated with instruction classes and/or instruction registers.

8. The data processing system of claim 7 , where the instruction classes are represented by a single bit or multiple bits.

Assignees

• IBM

Inventors

• Gschwind Michael K
• Salapura Valentina

Classifications

• G06F9/382

  Pipelined decoding, e.g. using predecoding · CPC title

• G06F9/3853

  of compound instructions · CPC title

• G06F9/30145 Primary

  Instruction analysis, e.g. decoding, instruction word fields · CPC title