[MLIR][Ptr] Allocating and deallocating ptr memrefs

[Dasor]

Hi, I'm using the ptr dialect to lower some custom code, at some point I get something like this (minimal example to showcase this issue, does nothing relevant)

module {
  func.func @kernel(%arg0: !ptr.ptr<#ptr.generic_space>) {
    %c0 = arith.constant 0 : index
    %c1 = arith.constant 1 : index
    %c128 = arith.constant 128 : index
    %alloc = memref.alloc() {alignment = 64 : i64} : memref<128x!ptr.ptr<#ptr.generic_space>>
    scf.for %arg1 = %c0 to %c128 step %c1 {
      memref.store %arg0, %alloc[%arg1] : memref<128x!ptr.ptr<#ptr.generic_space>>
    }
    memref.dealloc %alloc : memref<128x!ptr.ptr<#ptr.generic_space>>
    return
  }
}

However when trying to lower those memrefs with --finalize-memref-to-llvm nothing changes. The issue is related to the TypeConverter as there is no conversion from !ptr.ptr to any llvm type so the DeallocOpLowering won't even run on this memrefs.

As I understood by looking at the docs here a ptr is just a struct with four uint32_t so I made a custom conversion on the TypeConverter but I'm getting and invalid free.

I've also seen that the ptr dialect is expected to grow soon so maybe this has already been addressed by someone. Tagging a couple of folks who seem active in this area:
@fabianmcg @joker-eph

Thanks!

[llvmbot]

@llvm/issue-subscribers-mlir

Author: Daniel (Dasor)

Hi, I'm using the ptr dialect to lower some custom code, at some point I get something like this (minimal example to showcase this issue, does nothing relevant)

module {
  func.func @<!-- -->kernel(%arg0: !ptr.ptr&lt;#ptr.generic_space&gt;) {
    %c0 = arith.constant 0 : index
    %c1 = arith.constant 1 : index
    %c128 = arith.constant 128 : index
    %alloc = memref.alloc() {alignment = 64 : i64} : memref&lt;128x!ptr.ptr&lt;#ptr.generic_space&gt;&gt;
    scf.for %arg1 = %c0 to %c128 step %c1 {
      memref.store %arg0, %alloc[%arg1] : memref&lt;128x!ptr.ptr&lt;#ptr.generic_space&gt;&gt;
    }
    memref.dealloc %alloc : memref&lt;128x!ptr.ptr&lt;#ptr.generic_space&gt;&gt;
    return
  }
}

However when trying to lower those memrefs with --finalize-memref-to-llvm nothing changes. The issue is related to the TypeConverter as there is no conversion from !ptr.ptr to any llvm type so the DeallocOpLowering won't even run on this memrefs.

As I understood by looking at the docs here a ptr is just a struct with four uint32_t so I made a custom conversion on the TypeConverter but I'm getting and invalid free.

I've also seen that the ptr dialect is expected to grow soon so maybe this has already been addressed by someone. Tagging a couple of folks who seem active in this area:
@fabianmcg @joker-eph

Thanks!

[fabianmcg]

Hi, thanks for the interest in ptr.

Right now there's no conversion from memrefs to ptr yet, neither from ptr to llvm. However, I just put up a patch for them:

#156053

As soon as it lands your example should work.

[Dasor]

Yes, it does, thanks!