Villmow, Micah
2008-Oct-20 20:43 UTC
[LLVMdev] Virtual Register allocation across functions
Is there currently a way to have virtual register allocation information be saved across functions so that if I create a new virtual register in a function that it doesn't use a virtual register allocated in any previous function? Thanks, Micah Villmow Systems Engineer Advanced Technology & Performance Advanced Micro Devices Inc. 4555 Great America Pkwy, Santa Clara, CA. 95054 P: 408-572-6219 F: 408-572-6596 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20081020/935040b8/attachment.html>
No, there isn't something like that right now. What are you trying to accomplish? If you wish to implement this, it shouldn't be hard to do. Right now, MachineRegisterInfo re-starts virtual register number at TargetRegisterInfo::FirstVirtualRegister. You can add a mechanism to change that to a variable instead. Evan On Oct 20, 2008, at 1:43 PM, Villmow, Micah wrote:> Is there currently a way to have virtual register allocation > information be saved across functions so that if I create a new > virtual register in a function that it doesn’t use a virtual > register allocated in any previous function? > > Thanks, > > Micah Villmow > Systems Engineer > Advanced Technology & Performance > Advanced Micro Devices Inc. > 4555 Great America Pkwy, > Santa Clara, CA. 95054 > P: 408-572-6219 > F: 408-572-6596 > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20081020/2a81d501/attachment.html>
Villmow, Micah
2008-Oct-20 21:14 UTC
[LLVMdev] Virtual Register allocation across functions
I'm targeting a language that uses virtual registers and not physical registers. So the easiest way to implement this is to use virtual registers, except that they are being restarted after each function and clobbering registers in previous functions. For example: start function 0 r1024 = mov %var0.0 r1025 = mov %var0.1 lots of intermediate code call function1 w/ 3 parameters more intermediate code %r1300 = add %call.result, %r1024 end function 0 start function 1 %r1024 = mov %var1.0 %r1025 = mov %var1.1 %r1026 = mov %var1.2 some code return some value end function 0 The mov to r1024 in function 1 clobbers the data from function 0. The only ways I can think to get around this, is to push every virtual register used in a function to a stack or some internal data structure and then pull them back out for each function call. The other option is to run a separate pass just to renumber register. This is not what I would like to do as the easiest solution is just to get a variable start point. Any other ideas that might accomplish what I want, that I might be missing? Thanks, ________________________________ From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Evan Cheng Sent: Monday, October 20, 2008 2:03 PM To: LLVM Developers Mailing List Subject: Re: [LLVMdev] Virtual Register allocation across functions No, there isn't something like that right now. What are you trying to accomplish? If you wish to implement this, it shouldn't be hard to do. Right now, MachineRegisterInfo re-starts virtual register number at TargetRegisterInfo::FirstVirtualRegister. You can add a mechanism to change that to a variable instead. Evan On Oct 20, 2008, at 1:43 PM, Villmow, Micah wrote: Is there currently a way to have virtual register allocation information be saved across functions so that if I create a new virtual register in a function that it doesn't use a virtual register allocated in any previous function? Thanks, Micah Villmow Systems Engineer Advanced Technology & Performance Advanced Micro Devices Inc. 4555 Great America Pkwy, Santa Clara, CA. 95054 P: 408-572-6219 F: 408-572-6596 _______________________________________________ LLVM Developers mailing list LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20081020/98005733/attachment.html>