Jin-Gu
Thanks for your suggestion. Using liveness information for virtual register is a
good idea, but what I am working on is a source-to-source compiler, so I prefer
to use FunctionPass instead of MachineFunctionPass.
Interestingly I found a FunctionPass example for classic liveness data flow
equation.
http://cs.pub.ro/~cpl/wiki/images/1/15/Hello.txt
------------------------------------------------
--Zhanglin
----- Original Message -----
From: Jin Gu Kang <jaykang10 at imrc.kist.re.kr>
To: Zhanglin Liu <way_lzl at sina.com>
Subject: RE: [LLVMdev] Where is liveness analysis pass?
Date: 2011-1-13 16:28:59
Hi Zhanglin.
First I suggest to read http://llvm.org/docs/CodeGenerator.html#liveintervals.
:)
I saw the basic processing order of Live interval in backend LLVM source code as
following:
1. LiveVariables::runOnMachineFunction()
"lib/CodeGen/LiveVariables.cpp"
--> This pass computes live variable information for each virtual register
and register allocatable physical register in the function. (Target dependent)
2. SlotIndexes::runOnMachineFunction() "lib/CodeGen/SlotIndexes.cpp"
--> This pass assigns indexes to each instruction and basic blocks
3. LiveIntervals::runOnMachineFunction()
"lib/CodeGen/LiveIntervalAnalysis.cpp"
--> This pass computes live interval for live variables.
4. SimpleRegisterCoalescing::runOnMachineFunction
"lib/CodeGen/SimpleRegisterCoalescing.cpp"
-> After SimpleRegisterCoalescing, live intervals are merged.
As you know, liveness inforamtion in backend is target dependent.
If you want to use target independent liveness information, I suggest you to use
live variable information for virtual register in
"LiveVariables::runOnMachineFunction()" pass.
Best regards,
Jin-Gu Kang
