[Mlir-commits] [mlir] [MLIR][SCF] Add canonicalization pattern to fold away iter args of scf.forall (PR #90189)

[Matthias Springer]

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@@ -1509,6 +1510,203 @@ class ForallOpControlOperandsFolder : public OpRewritePattern<ForallOp> {
   }
 };
 
+/// The following canonicalization pattern folds the iter arguments of
+/// scf.forall op if :-
+/// 1. The corresponding result has zero uses.
+/// 2. The iter argument is NOT being modified within the loop body.
+/// uses.
+///
+/// Example of first case :-
+///  INPUT:
+///   %res:3 = scf.forall ... shared_outs(%arg0 = %a, %arg1 = %b, %arg2 = %c)
+///            {
+///                ...
+///                <SOME USE OF %arg0>
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matthias-springer wrote:

Kind of. Another legitimate use case is to extract a slice from the bbarg and then pass the slice into destination-style op (such as a linalg.matmul). (tensor.extract_slice is not a destination-style op and the bbarg is not directly used as a destination.)


https://github.com/llvm/llvm-project/pull/90189