[LLVMdev] How to Allocate a Variable to a Specific register

Avinash Bole boleavinash at gmail.com
Thu Mar 12 23:52:28 PDT 2015


Hi,

Im trying to allocate registers for given code..,and my requirement is to
allocate a specific register to a given variable( ex:  int a ; // I want to
allocate register R1 to a).

I think one way to do this is by writing an llvm pass as described here
<http://llvm.org/docs/WritingAnLLVMPass.html#the-machinefunctionpass-class>.
But im not sure it will work..,Another way i thought of is to change
Allocation order in "AltOrder" in "xxxRegisterInfo.td". This worked for 1
variable..,but if i have two or more variables and more registers.,i cant
get the exact register i want for the exact variable.

Please suggest me a way to do this.
Also..,Is there a way to check contents of each "bit" in a register?

Thanks,
Avinash
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