[llvm] r269969 - When looking for a spill slot in reg scavenger, find one that matches RC

[Krzysztof Parzyszek via llvm-commits]

Hi Jordy,

Does this fix work for you?

   unsigned SI = Scavenged.size(), Diff = UINT_MAX;
+ int FIB = MFI.getObjectIndexBegin(), FIE = MFI.getObjectIndexEnd();
   for (unsigned I = 0; I < Scavenged.size(); ++I) {
     if (Scavenged[I].Reg != 0)
       continue;
     // Verify that this slot is valid for this register.
     int FI = Scavenged[I].FrameIndex;
+   if (FI < FIB || FI >= FIE)
+     continue;
     unsigned S = MFI.getObjectSize(FI);
     unsigned A = MFI.getObjectAlignment(FI);

-Krzysztof


On 5/20/2016 7:04 AM, Jordy Potman wrote:
> Hi Krzysztof,
>
> I'm seeing an "Invalid Object Idx" assert in the call to
> MFI.getObjectSize(FI) in the code below on my out of tree target after
> this commit.
>
>     +    // Verify that this slot is valid for this register.
>     +    int FI = Scavenged[I].FrameIndex;
>     +    unsigned S = MFI.getObjectSize(FI);
>     +    unsigned A = MFI.getObjectAlignment(FI);
>     +    if (NeedSize > S || NeedAlign > A)
>     +      continue;
>
>
> The reason for this is that the Scavenged vector may contain a
> ScavengedInfo structure with a FrameIndex of -1 after the first call of
> scavengeRegister on targets where there is no spill slot but the target
> knows how to save/restore the register (using
> TRI->saveScavengerRegister). This ScavengedInfo structure with a
> FrameIndex of -1 is added to the Scavenged vector by the code on lines
> 425-429 in the first call of scavengeRegister.
>
> I have fixed this in my tree by adding
>
> if (FI < 0)
>   continue;
>
> before the the call to MFI.getObjectSize(FI) in the code above, see the
> attached patch, but there may be a cleaner/better solution.
>
> Jordy


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