Using Heuristic Value Prediction and Dynamic Task Granularity Resizing to Improve Software Speculation

Table 1

The HEUSPEC predictors.

Name	Base elements used	Especially applicable category	Speculative value depends on	Example
Reverse	1	BOOLEAN	The reverse of the value in the last iteration	Base[0]  =  ⟨1,1⟩  Result  =  ⟨𝟐,𝐑𝐞𝐯𝐞𝐫𝐬𝐞(𝟏)⟩
Conventional	1	CONSTANT, LADDER	The committed value in the shared space	Base[0]  =  ⟨1,135⟩  Result  =  ⟨𝟐,𝟏𝟑𝟓⟩
Restricted; random	2	RESTRICTED; RANDOM	A random number in a restricted value space	Base[0]  =  ⟨1,20⟩  Base[1]  =  ⟨2,5⟩; Result  =  ⟨𝟑,𝐑𝐚𝐧𝐝(𝟓,𝟏𝟐)⟩
Linear	2	LINEAR	The linear extrapolation of last 2 committed values	Base[0]  =  ⟨1,20⟩  Base[1]  =  ⟨2,5⟩; Result  =  ⟨𝟑,𝐋𝐢𝐧𝐞𝐚𝐫𝐄𝐱𝐭𝐫𝐚(𝟏,𝟐𝟎,𝟐,𝟓)⟩
Quadratic	3	LINEAR, CONSTANT	The quadratic extrapolation of last 3 committed values	Base[0]  =  ⟨1,20⟩  Base[1]  =  ⟨2,5⟩; Base[2]  =  ⟨3,8⟩  Result  =  ⟨𝟒,𝐐𝐮𝐚𝐝𝐄𝐱𝐭𝐫𝐚(𝟏,𝟐𝟎,𝟐,𝟓,𝟑,𝟖)⟩