[LLVMdev] Order of glued nodes during scheduling

[Hal Finkel]

Andy, et al.,

I'm experimenting with better condition-register-bit tracking in the PowerPC backend, and I've run across a problem: the scheduling seems to be scheduling glued nodes out of order:

Starting with this:

        0x10015677970: i32 = Register %CR0

        0x10015679080: i32 = TargetConstant<3>
...
          0x10015671b80: i32 = TargetConstant<1>

        0x10015678d80: i32,glue = ANDIo 0x100156746c0, 0x10015671b80 [ORD=49]

      0x100156749c0: i1 = EXTRACT_SUBREG 0x10015677970, 0x10015679080, 0x10015678d80:1 [ORD=49]

    0x10015671d80: ch = CopyToReg 0x100156463c8, 0x10015677c70, 0x100156749c0 [ORD=49]
...

the two glued nodes are put together in the same SU:

SU(2): 0x100156749c0: i1 = EXTRACT_SUBREG 0x10015677970, 0x10015679080, 0x10015678d80:1 [ORD=49] [ID=2]

    0x10015678d80: i32,glue = ANDIo 0x100156746c0, 0x10015671b80 [ORD=49] [ID=2]

and scheduled together, yielding this schedule:

SU(3): 0x100156746c0: i32,ch = LWZ 0x10015674fc0, 0x10015678b80, 0x10015672280<Mem:LD4[FixedStack1+8](align=8)> [ORD=49] [ID=3]

SU(2): 0x100156749c0: i1 = EXTRACT_SUBREG 0x10015677970, 0x10015679080, 0x10015678d80:1 [ORD=49] [ID=2]

    0x10015678d80: i32,glue = ANDIo 0x100156746c0, 0x10015671b80 [ORD=49] [ID=2]

SU(1): 0x10015671d80: ch = CopyToReg 0x100156463c8, 0x10015677c70, 0x100156749c0 [ORD=49] [ID=1]

SU(0): 0x100156762d0: ch = TokenFactor 0x10015678c80, 0x10015679180, 0x10015671d80 [ORD=50] [ID=0]

which then asserts:

llvm-trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp:292: unsigned int llvm::InstrEmitter::getVR(llvm::SDValue, llvm::DenseMap<llvm::SDValue, unsigned int, llvm::DenseMapInfo<llvm::SDValue> >&): Assertion `I != VRBaseMap.end() && "Node emitted out of order - late"' failed.

What's gone wrong here? Is the order in the SU wrong, or should the scheduler invert the order for scheduling, or something else?

Thanks again,
Hal

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory