search for: t2ldrsb_pre

Hi, I have a question about the definitions of t2LDRSB and t2LDRSB_PRE in ARMInstrThumb2.td : I was aware that the definitions of target RegisterClass (outs) are different in t2LDRSB and t2LDRSB_PRE. While t2LDRSB uses rGPR, t2LDRSB_PRE uses GPR. I wonder if lr and pc are already prevented from being allocated in pre-indexing case, because of some register hint t...

Hi Junbum, > I was aware that the definitions of target RegisterClass (outs) are different in t2LDRSB and t2LDRSB_PRE. While t2LDRSB uses rGPR, t2LDRSB_PRE uses GPR. I wonder if lr and pc are already prevented from being allocated in pre-indexing case, because of some register hint that is being enforced? They're not allocated during CodeGen because of the Reserved.set(…) calls in ARMBaseRegisterInfo.cpp....

...and freezing lr and pc during register allocation in writeback version? Thanks, Junbum On May 23, 2013, at 11:51 AM, Tim Northover <tnorthover at apple.com> wrote: > Hi Junbum, > >> I was aware that the definitions of target RegisterClass (outs) are different in t2LDRSB and t2LDRSB_PRE. While t2LDRSB uses rGPR, t2LDRSB_PRE uses GPR. I wonder if lr and pc are already prevented from being allocated in pre-indexing case, because of some register hint that is being enforced? > > They're not allocated during CodeGen because of the Reserved.set(…) calls in ARMBaseRegister...