[Mlir-commits] [mlir] [mlir][ArmSME] Support 4-way widening outer products (PR #79288)

[Cullen Rhodes]

================
@@ -225,37 +271,173 @@ class OuterProductFusion2Way
 
     return success();
   }
+};
 
-  // An outer product is compatible if all of the following are true:
-  // - the result type matches `resultType`.
-  // - the defining operations of the inputs are identical and of the type
-  //   `ExtOp`.
-  // - the input types of the defining operations are identical and match
-  //   `inputType`.
-  template <typename ExtOp>
-  LogicalResult isCompatible(PatternRewriter &rewriter,
-                             arm_sme::OuterProductOp op, VectorType resultType,
-                             VectorType inputType) const {
-    if (op.getResultType() != resultType)
-      return rewriter.notifyMatchFailure(op.getLoc(), [&](Diagnostic &diag) {
-        diag << "unsupported result type, expected " << resultType;
-      });
-
-    auto lhsDefOp = op.getLhs().getDefiningOp<ExtOp>();
-    auto rhsDefOp = op.getRhs().getDefiningOp<ExtOp>();
-
-    if (!lhsDefOp || !rhsDefOp)
-      return rewriter.notifyMatchFailure(
-          op, "defining op of outerproduct operands must be one of: "
-              "'arith.extf' or 'arith.extsi' or 'arith.extui'");
+// Fuse four 'arm_sme.outerproduct' operations that are chained via the
+// accumulator into 4-way outer product operation.
+class OuterProductFusion4Way
+    : public OpRewritePattern<arm_sme::OuterProductOp> {
+public:
+  using OpRewritePattern::OpRewritePattern;
 
-    auto lhsInType = cast<VectorType>(lhsDefOp.getIn().getType());
-    auto rhsInType = cast<VectorType>(rhsDefOp.getIn().getType());
+  LogicalResult matchAndRewrite(arm_sme::OuterProductOp op,
+                                PatternRewriter &rewriter) const override {
+    SmallVector<arm_sme::OuterProductOp, 4> outerProductChain;
+    outerProductChain.push_back(op);
+
+    for (int i = 0; i < 3; ++i) {
+      auto currentOp = outerProductChain.back();
+      auto acc = currentOp.getAcc();
+      if (!acc)
+        return rewriter.notifyMatchFailure(op, MATCH_FAILURE_NO_ACCUMULATOR);
+      auto previousOp = acc.getDefiningOp<arm_sme::OuterProductOp>();
+      if (!previousOp)
+        return rewriter.notifyMatchFailure(
+            op, MATCH_FAILURE_EXPECTED_OUTERPRODUCT_DEF_OP);
+      if (!previousOp->hasOneUse())
+        return rewriter.notifyMatchFailure(
+            op, MATCH_FAILURE_OUTERPRODUCT_NOT_SINGLE_USE);
+      if (previousOp.getKind() != currentOp.getKind())
+        return rewriter.notifyMatchFailure(
+            op, MATCH_FAILURE_INCONSISTENT_COMBINING_KIND);
+      if (bool(previousOp.getLhsMask()) != bool(currentOp.getLhsMask()))
+        return rewriter.notifyMatchFailure(
+            op, MATCH_FAILURE_INCONSISTENT_COMBINING_KIND);
+      outerProductChain.push_back(previousOp);
+    }
 
-    if (lhsInType != inputType || rhsInType != inputType)
-      return rewriter.notifyMatchFailure(op.getLoc(), [&](Diagnostic &diag) {
-        diag << "unsupported input type, expected " << inputType;
-      });
+    if (failed(canFuseOuterProducts(rewriter, outerProductChain)))
+      return failure();
+
+    arm_sme::OuterProductOp op1 = outerProductChain[3];
+    arm_sme::OuterProductOp op2 = outerProductChain[2];
+    arm_sme::OuterProductOp op3 = outerProductChain[1];
+    arm_sme::OuterProductOp op4 = outerProductChain[0];
+
+    auto loc = op.getLoc();
+
+    auto packInputs = [&](Value lhs, Value rhs) {
+      auto inputType = cast<VectorType>(lhs.getType());
+      VectorType inputTypeX2 =
+          VectorType::Builder(inputType).setDim(0, inputType.getShape()[0] * 2);
+      return rewriter.create<LLVM::experimental_vector_interleave2>(
+          loc, inputTypeX2, lhs, rhs);
+    };
+
+    auto lhs0 = packInputs(op1.getLhs().getDefiningOp()->getOperand(0),
+                           op3.getLhs().getDefiningOp()->getOperand(0));
+    auto lhs1 = packInputs(op2.getLhs().getDefiningOp()->getOperand(0),
+                           op4.getLhs().getDefiningOp()->getOperand(0));
+    auto lhs = packInputs(lhs0, lhs1);
+
+    auto rhs0 = packInputs(op1.getRhs().getDefiningOp()->getOperand(0),
+                           op3.getRhs().getDefiningOp()->getOperand(0));
+    auto rhs1 = packInputs(op2.getRhs().getDefiningOp()->getOperand(0),
+                           op4.getRhs().getDefiningOp()->getOperand(0));
+    auto rhs = packInputs(rhs0, rhs1);
+
+    Value lhsMask, rhsMask;
+    if (op1.getLhsMask() || op2.getLhsMask() || op3.getLhsMask() ||
+        op4.getLhsMask()) {
+      auto lhs0Mask = packInputs(op1.getLhsMask(), op3.getLhsMask());
+      auto lhs1Mask = packInputs(op2.getLhsMask(), op4.getLhsMask());
+      lhsMask = packInputs(lhs0Mask, lhs1Mask);
+
+      auto rhs0Mask = packInputs(op1.getRhsMask(), op3.getRhsMask());
+      auto rhs1Mask = packInputs(op2.getRhsMask(), op4.getRhsMask());
+      rhsMask = packInputs(rhs0Mask, rhs1Mask);
+    }
+
+    auto lhsExtOp = op.getLhs().getDefiningOp();
+    auto rhsExtOp = op.getRhs().getDefiningOp();
+
+    arm_sme::CombiningKind kind = op.getKind();
+    if (kind == arm_sme::CombiningKind::Add) {
+      if (isa<arith::ExtSIOp>(lhsExtOp) && isa<arith::ExtSIOp>(rhsExtOp))
+        rewriter.replaceOpWithNewOp<arm_sme::SMopa4WayOp>(
+            op4, op.getResultType(), lhs, rhs, lhsMask, rhsMask, op1.getAcc());
+      else if (isa<arith::ExtUIOp>(lhsExtOp) && isa<arith::ExtUIOp>(rhsExtOp))
+        rewriter.replaceOpWithNewOp<arm_sme::UMopa4WayOp>(
+            op4, op.getResultType(), lhs, rhs, lhsMask, rhsMask, op1.getAcc());
+      else if (isa<arith::ExtSIOp>(lhsExtOp) && isa<arith::ExtUIOp>(rhsExtOp))
+        rewriter.replaceOpWithNewOp<arm_sme::SuMopa4WayOp>(
+            op4, op.getResultType(), lhs, rhs, lhsMask, rhsMask, op1.getAcc());
+      else if (isa<arith::ExtUIOp>(lhsExtOp) && isa<arith::ExtSIOp>(rhsExtOp))
+        rewriter.replaceOpWithNewOp<arm_sme::UsMopa4WayOp>(
+            op4, op.getResultType(), lhs, rhs, lhsMask, rhsMask, op1.getAcc());
----------------
c-rhodes wrote:

good point, done, although I've also added braces as per the [coding standards](https://llvm.org/docs/CodingStandards.html#don-t-use-braces-on-simple-single-statement-bodies-of-if-else-loop-statements) so the format has changed 

https://github.com/llvm/llvm-project/pull/79288