llvm-project

fc093f13 - [mlir][Interfaces] Add interface methods to allow reifying single result/single dim of result. (#162924)

[mlir][Interfaces] Add interface methods to allow reifying single result/single dim of result. (#162924) Current implementation of `reifyResultShapes` forces all implementations to return all dimensions of all results. This can be wasteful when you only require dimensions of one result, or a single dimension of a result. Further this also creates issues with using patterns to resolve the `tensor.dim` and `memref.dim` operations since the extra operations created result in the pattern rewriter entering an infinite loop (eventually breaking out of the loop due to the iteration limit on the pattern rewriter). This is demonstrated by some of the test cases added here that hit this limit when using `--resolve-shaped-type-result-dims` and `--resolve-ranked-shaped-type-result-dims`. To resolve this issue the interface should allow for creating just the operations needed. This change is the first step in resolving this. The original implementation was done with the restriction in mind that it might not always be possible to compute dimension of a single result or one dimension of a single result in all cases. To account for such cases, two additional interface methods are added - `reifyShapeOfResult` (which allows reifying dimensions of just one result), has a default implementation that calls `reifyResultShapes` and returns the dimensions of a single result. - `reifyDimOfResult` (which allows reifying a single dimension of a single result) has a default implementation that calls `reifyDimOfResult` and returns the value for the dimension of the result (which in turn for the default case would call `reifyDimOfResult`). While this change sets up the interface, ideally most operations will implement the `refiyDimOfResult` when possible. For almost all operations in tree this is true. Subsequent commits will change those incrementally. Some of the tests added here that check that the default implementations for the above method work as expected, also end up hitting the pattern rewriter limit when using `--resolve-ranked-shaped-type-result-dims`/ `--resolve-ranked-shaped-type-result-dims`. For testing purposes, a flag is added to these passes that ignore the error returned by the pattern application (this flag is left on by default to maintain current state). Changes required downstream to integrate this change 1. In operation definitions in .td files, for those operations that implement the `ReifyRankedShapedTypeOpInterface`. ``` def <op-name> : Op<..., [..., DeclareOpInterfaceMethods[ReifyRankedShapedTypeOpInterface]]> ``` should be changed to ``` def <op-name> : Op<..., [..., DeclareOpInterfaceMethods[ReifyRankedShapedTypeOpInterface, [ "reifyResultShapes"]]]> ``` --------- Signed-off-by: MaheshRavishankar <mahesh.ravishankar@gmail.com>