search for: 6688b

I have never quite understood the "phi def" concept of LiveInterval. I understand that a phi def LiveRange originally came from a phi instruction but I'm not sure how to use the information after phi elimination. For example, I have this LiveInterval: [3472r,6688B:3)[6688B,8240B:2)[8240B,8976B:0)[8976B,12160B:1)[12160B,13744B:4)[13744B,14480B:5)[1448 0B,18048B:6)[18048B,19792B:7)[19792B,20192r:8) 0 at 8240B-phi 1 at 8976B-phi 2 at 6688B-phi 3 at 3472r 4 at 12160B -phi 5 at 13744B-phi 6 at 14480B-phi 7 at 18048B-phi 8 at 19792B-phi There is only one non-phi...

...o understand: 4B A = ... 10B D = use A This seems straightforward. The instruction at slot 10 uses A at 10r and the VNInfo for 10r should have a def at 4r. But that's not right! I am staring at the following: LiveInterval: %vreg163 [5404r,6432B:0)[6480B,6688r:0) 0 at 5404r Instruction: 6688B %RDX<def> = COPY %vreg163 There is NO VNInfo at 6688r (the live range excludes it) but there is a VNInfo at 6688e (Slot_EarlyClobber). How am I supposed to know which slot to look at for a register use? Are ALL uses always at Slot_EarlyClobber? The comment for Slot_EarlyClobber sure doesn...

...e A > > This seems straightforward. The instruction at slot 10 uses A at 10r > and the VNInfo for 10r should have a def at 4r. > > But that's not right! I am staring at the following: > > LiveInterval: %vreg163 [5404r,6432B:0)[6480B,6688r:0) 0 at 5404r > Instruction: 6688B %RDX<def> = COPY %vreg163 An instruction by itself doesn't have any meaningful slot. It shows as B, but only because B is the default slot. For a given register you get the actual slot from the live interval. -Krzysztof