[Mlir-commits] [mlir] [mlir][arith] Check for valid IR in BitcastOp::fold. (PR #100743)

[Mehdi Amini]

joker-eph wrote:

> > In which context are we folding invalid IR?
> 
> Before the folder is called, the IR looks like this:
> 
> ```mlir
> %0 = arith.constant 0 : i32
> %1 = arith.bitcast %0 : i32 to i64
> ```
> 
> That's invalid because `i32` is not `BitcastOp::areCastCompatible` to `i64`.
> 
> The folder doesn't verify that but instead attemps to create an `IntegerAttr` with type `i32` and an `APInt` value of type `i64`, which breaks an assertion in the call stack `IntegerAttr::get`.


It's not clear to me when should the folder be resilient to invalid IR though: this is what I mean about "In which context are we folding invalid IR?" ; this is a general question beyond the specific IR you have at hand: I need to know how you end up in this situation instead of the specific invalid IR that triggers this crash. 


https://github.com/llvm/llvm-project/pull/100743