[PATCH] D20847: BitCast infinite loop fix

[Guozhi Wei via llvm-commits]

Carrot added a comment.



>   xB = load (type B);

>   xA = load (type A);

>   +yA = (A)xB;             // B -> A

>   +zAn = PHI[yA, xA];      // PHI

>   +zBn = (B)zAn;           // A -> B

>   store zAn;

>   store zBn;


optimizeBitCastFromPhi generates

  +zBn = (B)zAn;           // A -> B

and expects it will be combined with the following store instruction to another

  store zAn

But unfortunately before combineStoreToValueType is called on the store instruction, optimizeBitCastFromPhi is called on the new BitCast again, and this pattern repeats indefinitely.


Repository:
  rL LLVM

https://reviews.llvm.org/D20847