[Mlir-commits] [mlir] [mlir][vector] Separate multi_reduce lowering into transformations, flattening, and unrolling. (PR #178974)

[Jakub Kuderski]

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@@ -60,6 +60,35 @@ void populateVectorContractLoweringPatterns(
 void populateVectorOuterProductLoweringPatterns(RewritePatternSet &patterns,
                                                 PatternBenefit benefit = 1);
 
+/// Collect a set of patterns to set invariants for vector.multi_reduction's
+/// conversion. The patterns comprise:
+///
+/// [InnerOuterDimReductionConversion]
+/// Rewrites vector.multi_reduction such that all reduction dimensions are
+/// either innermost or outermost, by adding the proper vector.transpose
+/// operations.
+///
+/// [OneDimMultiReductionToTwoDim]
+/// For cases that reduce to 1-D vector<k> reduction (and are thus missing
+/// either a parallel or a reduction), we lift them back up to 2-D with a simple
+/// vector.shape_cast to vector<1xk> so that the other patterns can kick in,
+/// thus fully exiting out of the vector.multi_reduction abstraction.
+void populateVectorMultiReductionInnerOuterDimPatterns(
+    RewritePatternSet &patterns, VectorMultiReductionLowering options,
+    PatternBenefit benefit = 1);
+
+/// Collect a set of patterns to convert vector.multi_reduction op into
+/// a sequence of vector.reduction ops. The patterns comprise:
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kuhar wrote:

Below you say that this will end up being 2D multi_reductions

https://github.com/llvm/llvm-project/pull/178974