Fix crash in scf.parallel verifier

[mehdi_amini]

Summary

Fixes #59989

mlir/lib/Dialect/SCF/IR/SCF.cpp

#include "mlir/Dialect/SCF/IR/SCFOps.cpp.inc"
   addInterfaces<SCFInlinerInterface>();
 }
 
 /// Default callback for IfOp builders. Inserts a yield without arguments.
 void mlir::scf::buildTerminatedBody(OpBuilder &builder, Location loc) {
   builder.create<scf::YieldOp>(loc);
 }
 
+/// Verifies that the first block of the given `region` is terminated by a
+/// TerminatorTy. Reports errors on the given operation if it is not the case.
+template <typename TerminatorTy>
+static TerminatorTy verifyAndGetTerminator(Operation *op, Region &region,
+                                           StringRef errorMessage) {
+  Operation *terminatorOperation = nullptr;
+  if (!region.empty() && !region.front().empty()) {
+    terminatorOperation = &region.front().back();
+    if (auto yield = dyn_cast_or_null<TerminatorTy>(terminatorOperation))
+      return yield;
+  }
+  auto diag = op->emitOpError(errorMessage);
+  if (terminatorOperation)
+    diag.attachNote(terminatorOperation->getLoc()) << "terminator here";
+  return nullptr;
+}
+
 //===----------------------------------------------------------------------===//
 // ExecuteRegionOp
 //===----------------------------------------------------------------------===//
 
 /// Replaces the given op with the contents of the given single-block region,
 /// using the operands of the block terminator to replace operation results.
 static void replaceOpWithRegion(PatternRewriter &rewriter, Operation *op,
                                 Region &region, ValueRange blockArgs = {}) {
return emitOpError() << "expects the same number of induction variables: "
                          << body->getNumArguments()
                          << " as bound and step values: " << stepValues.size();
   for (auto arg : body->getArguments())
     if (!arg.getType().isIndex())
       return emitOpError(
           "expects arguments for the induction variable to be of index type");
 
   // Check that the yield has no results
-  Operation *yield = body->getTerminator();
+  auto yield = verifyAndGetTerminator<scf::YieldOp>(
+      *this, getRegion(), "expects body to terminate with 'scf.yield'");
+  if (!yield)
+    return failure();
   if (yield->getNumOperands() != 0)
-    return yield->emitOpError() << "not allowed to have operands inside '"
-                                << ParallelOp::getOperationName() << "'";
+    return yield.emitOpError() << "not allowed to have operands inside '"
 
   // Check that the number of results is the same as the number of ReduceOps.
   SmallVector<ReduceOp, 4> reductions(body->getOps<ReduceOp>());
   auto resultsSize = getResults().size();
   auto reductionsSize = reductions.size();
   auto initValsSize = getInitVals().size();
   if (resultsSize != reductionsSize)
     return emitOpError() << "expects number of results: " << resultsSize
if (left[i] != right[i]) {
                         << " and " << right[i];
       return diag;
     }
   }
 
   return success();
 }
 
-/// Verifies that the first block of the given `region` is terminated by a
-/// YieldOp. Reports errors on the given operation if it is not the case.
-template <typename TerminatorTy>
-static TerminatorTy verifyAndGetTerminator(scf::WhileOp op, Region &region,
-                                           StringRef errorMessage) {
-  Operation *terminatorOperation = nullptr;
-  if (!region.empty() && !region.front().empty()) {
-    terminatorOperation = &region.front().back();
-    if (auto yield = dyn_cast_or_null<TerminatorTy>(terminatorOperation))
-      return yield;
-  }
-  auto diag = op.emitOpError(errorMessage);
-  if (terminatorOperation)
-    diag.attachNote(terminatorOperation->getLoc()) << "terminator here";
-  return nullptr;
-}
-
 LogicalResult scf::WhileOp::verify() {
   auto beforeTerminator = verifyAndGetTerminator<scf::ConditionOp>(
       *this, getBefore(),
       "expects the 'before' region to terminate with 'scf.condition'");
   if (!beforeTerminator)
     return failure();
 
   auto afterTerminator = verifyAndGetTerminator<scf::YieldOp>(

mlir/test/Dialect/SCF/invalid.mlir

 func.func @switch_missing_terminator(%arg0: index, %arg1: i32) {
   // expected-error @below {{'scf.index_switch' op expected region to end with scf.yield, but got func.return}}
   "scf.index_switch"(%arg0) ({
     "scf.yield"() : () -> ()
   }, {
     return
   }) {cases = array<i64: 1>} : (index) -> ()
 }
+
+// -----
+
+func.func @parallel_missing_terminator(%0 : index) {
+  // expected-error @below {{'scf.parallel' op expects body to terminate with 'scf.yield'}}
+  "scf.parallel"(%0, %0, %0) ({
+  ^bb0(%arg1: index):
+    // expected-note @below {{terminator here}}
+    %2 = "arith.constant"() {value = 1.000000e+00 : f32} : () -> f32
+  }) {operand_segment_sizes = array<i32: 1, 1, 1, 0>} : (index, index, index) -> ()
+  return
+}
+