[MLIR][Shape] Use callback builder again

[frgossen]

Summary

The issue that callback builders caused during rollback of conversion patterns
has been resolved. We can use them again.
See https://bugs.llvm.org/show_bug.cgi?id=46731

[herhut]

Thanks!

mlir/lib/Conversion/ShapeToSCF/ShapeToSCF.cpp

ShapeOfOpConverter::matchAndRewrite(ShapeOfOp op, ArrayRef<Value> operands,
   auto rankVal = rewriter.create<mlir::RankOp>(loc, tensorVal);
   auto i64Ty = rewriter.getI64Type();
   auto memTy = MemRefType::get({ShapedType::kDynamicSize}, i64Ty);
   auto memVal = rewriter.create<AllocaOp>(loc, memTy, ValueRange({rankVal}));
 
   // Copy shape extents to stack-allocated memory.
   auto zeroVal = rewriter.create<ConstantIndexOp>(loc, 0);
   auto oneVal = rewriter.create<ConstantIndexOp>(loc, 1);
-  auto loop = rewriter.create<scf::ForOp>(loc, zeroVal, rankVal, oneVal);
-  {
-    OpBuilder::InsertionGuard guard(rewriter);
-    rewriter.setInsertionPointToStart(loop.getBody());
-    auto iVal = loop.getInductionVar();
+  rewriter.create<scf::ForOp>(
+      loc, zeroVal, rankVal, oneVal, llvm::None,
+      [&](OpBuilder &b, Location loc, Value iVal, ValueRange args) {
         auto dimVal = rewriter.create<DimOp>(loc, tensorVal, iVal);
         auto dimIntVal = rewriter.create<IndexCastOp>(loc, dimVal, i64Ty);
         rewriter.create<StoreOp>(loc, dimIntVal, memVal, ValueRange{iVal});
-  }
+        rewriter.create<scf::YieldOp>(loc);
+      });
 
   // Load extents to tensor value.
   auto shapeIntVal = rewriter.create<TensorLoadOp>(loc, memVal);
   auto indexTy = rewriter.getIndexType();
   auto shapeTy = RankedTensorType::get({ShapedType::kDynamicSize}, indexTy);
   rewriter.replaceOpWithNewOp<IndexCastOp>(op.getOperation(), shapeIntVal,
                                            shapeTy);
   return success();