Optimizing Instruction Scheduling and Register Allocation for Register-File-Connected Clustered VLIW Architectures

Algorithm 2

Localization-enhanced register allocation mechanism.

Input:

   The variable needs to be allocated, 𝑣;

   Living range of that variable;

Output:

   Register allocation of variables 𝑣;

(1) if  𝑣 is active at the exit of BB, and global register 𝑔 is available at that time  then

(2)  Allocate 𝑣 to 𝑔

(3)  Update preferred register for related variables

(4) end if

(5) if  𝑣 has preferred register 𝑝_𝑟  then

(6)   if  𝑝_𝑟 is a global register  then

(7)     if  𝑝_𝑟 is available, and one of the uses has different cluster from the def of 𝑣  then

(8)     Allocate 𝑣 to 𝑝_𝑟

(9)     Update preferred register for related variables

(10)   end if

(11)   else

(12)    if  𝑝_𝑟 is available, and all the uses has same cluster as the def of 𝑣  then

(13)     Allocate 𝑣 to 𝑝_𝑟

(14)     Update preferred register for related variables

(15)    end if

(16)   end if

(17) else

(18)   if  One of the uses has different cluster from the def of 𝑣  then

(19)    if  Global register 𝑔 is available  then

(20)     Allocate 𝑣 to 𝑔

(21)     Update preferred register for related variables

(22)    else

(23)     Insert spill and restore instructions

(24)    end if

(25)   else

(26)    if  Local register 𝑙 is available  then

(27)     Allocate 𝑣 to 𝑙

(28)     Update preferred register for related variables

(29)    else

(30)     Insert spill and restore instructions

(31)     end if

(32)   end if

(33) end if