[Mlir-commits] [mlir] [mlir][OpenMP] inscan reduction modifier and scan op mlir support (PR #114737)

[Michael Klemm]

================
@@ -2840,6 +2886,54 @@ void MaskedOp::build(OpBuilder &builder, OperationState &state,
   MaskedOp::build(builder, state, clauses.filteredThreadId);
 }
 
+//===----------------------------------------------------------------------===//
+// Spec 5.2: Scan construct (5.6)
+//===----------------------------------------------------------------------===//
+
+void ScanOp::build(OpBuilder &builder, OperationState &state,
+                   const ScanOperands &clauses) {
+  ScanOp::build(builder, state, clauses.inclusiveVars, clauses.exclusiveVars);
+}
+
+LogicalResult ScanOp::verify() {
+  if (hasExclusiveVars() && hasInclusiveVars()) {
+    return emitError(
+        "Exactly one of EXCLUSIVE or INCLUSIVE clause is expected");
+  }
+  const OperandRange &scanVars =
+      hasExclusiveVars() ? getExclusiveVars() : getInclusiveVars();
+  auto verifyScanVarsInReduction = [&scanVars](OperandRange reductionVars) {
+    for (const auto &it : scanVars)
+      if (!llvm::is_contained(reductionVars, it))
+        return false;
+    return true;
+  };
+  if (mlir::omp::WsloopOp parentOp =
+          (*this)->getParentOfType<mlir::omp::WsloopOp>()) {
+    if (parentOp.getReductionModAttr() &&
+        parentOp.getReductionModAttr().getValue() ==
+            mlir::omp::ReductionModifier::InScan) {
+      if (!verifyScanVarsInReduction(parentOp.getReductionVars())) {
+        return emitError(
+            "List item should appear in REDUCTION clause of the parent");
+      }
+      return success();
+    }
+  } else if (mlir::omp::SimdOp parentOp =
+                 (*this)->getParentOfType<mlir::omp::SimdOp>()) {
+    if (parentOp.getReductionModAttr().getValue() ==
+        mlir::omp::ReductionModifier::InScan) {
+      if (!verifyScanVarsInReduction(parentOp.getReductionVars())) {
+        return emitError(
+            "List item should appear in REDUCTION clause of the parent");
+      }
+      return success();
+    }
+  }
+  return emitError("Scan Operation should be enclosed within a parent "
+                   "WORSKSHARING LOOP or SIMD with INSCAN reduction modifier");
----------------
mjklemm wrote:

```suggestion
  return emitError("SCAN directive needs to be enclosed within a parent "
                   "worksharing loop construct or SIMD construct with INSCAN reduction modifier");
```

https://github.com/llvm/llvm-project/pull/114737