[Mlir-commits] [mlir] [mlir][vector] Adds ToElementsToTargetShape pattern. (PR #166476)

[Jakub Kuderski]

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@@ -834,11 +834,100 @@ struct UnrollBroadcastPattern : public OpRewritePattern<vector::BroadcastOp> {
   vector::UnrollVectorOptions options;
 };
 
+/// Takes a 1 dimensional `vector.to_element` op and attempts to change it to
+/// the target shape.
+///
+/// ```
+/// // In SPIR-V's default environment vector of size 8
+/// // are not allowed.
+/// %elements:8 = vector.to_elements %v : vector<8xf32>
+///
+/// ===>
+///
+/// %v_0_to_3 = vector.extract %v[0] : vector<4xf32> from vector<8xf32>
+/// %v_4_to_7 = vector.extract %v[4] : vector<4xf32> from vector<8xf32>
+/// %elements_0:4 = vector.to_elements %v_0_to_3 : vector<4xf32>
+/// %elements_1:4 = vector.to_elements %v_4_to_7 : vector<4xf32>
+/// ```
+///
+/// This pattern may fail if the rank is not divisible by to a native shape
+/// or if the rank is already in the target shape and therefore it may be
+/// skipped.
+struct ToElementsToTargetShape final
+    : public OpRewritePattern<vector::ToElementsOp> {
+  ToElementsToTargetShape(MLIRContext *context,
+                          const vector::UnrollVectorOptions &options,
+                          PatternBenefit benefit = 1)
+      : OpRewritePattern<vector::ToElementsOp>(context, benefit),
+        options(options) {}
+
+  LogicalResult matchAndRewrite(vector::ToElementsOp op,
+                                PatternRewriter &rewriter) const override {
+    auto targetShape = getTargetShape(options, op);
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kuhar wrote:

spell out this type: https://llvm.org/docs/CodingStandards.html#use-auto-type-deduction-to-make-code-more-readable

https://github.com/llvm/llvm-project/pull/166476