Convert barriers into copies during allocation (iree-org#19735)

Content aliasing of barriers appears to be causing numerical issues.
This operation should just be removed safely however that appears to be
causing downstream issues. Swapping to a copy makes them go away however
this should be aliasable in the future.

Author: rsuderman

compiler/src/iree/compiler/Dialect/Stream/Transforms/ScheduleAllocation.cpp

@@ -668,6 +668,17 @@ applyAsyncCollectiveOp(IREE::Stream::AsyncCollectiveOp asyncOp,
 static LogicalResult applyAsyncBarrierOp(IREE::Stream::AsyncBarrierOp barrierOp,
                                          AllocationScope &scope,
                                          OpBuilder builder) {
+  // TODO: barriers are being treated as copies, they should just be metadata
+  // operations but currently it's causing failures to be removed.
+  auto sourceRange = scope.lookupResourceRange(barrierOp.getSource());
+  auto targetRange = scope.lookupResourceRange(barrierOp.getResult());
+
+  // Perform the copy.
+  builder.create<IREE::Stream::CmdCopyOp>(
+      barrierOp.getLoc(), sourceRange.resource, sourceRange.resourceSize,
+      sourceRange.offset, targetRange.resource, targetRange.resourceSize,
+      targetRange.offset, sourceRange.length);
+
   barrierOp.erase();
   return success();
 }