[clang] [CIR] Add offload container attribute (PR #206576)

[Henrich Lauko via cfe-commits]

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@@ -110,6 +111,87 @@ Operation *cir::CIRDialect::materializeConstant(mlir::OpBuilder &builder,
                                  mlir::cast<mlir::TypedAttr>(value));
 }
 
+//===----------------------------------------------------------------------===//
+// Dialect attribute verification
+//===----------------------------------------------------------------------===//
+
+static LogicalResult verifyOffloadKind(mlir::ModuleOp module,
+                                       cir::OffloadKind expected) {
+  auto attr = module->getAttrOfType<cir::OffloadKindAttr>(
+      cir::CIRDialect::getOffloadKindAttrName());
+  if (!attr)
+    return module.emitOpError()
+           << "expects '" << cir::CIRDialect::getOffloadKindAttrName()
+           << "' offload kind attribute";
+  if (attr.getValue() != expected)
+    return module.emitOpError()
+           << "expects '" << cir::CIRDialect::getOffloadKindAttrName()
+           << "' value '" << cir::stringifyOffloadKind(expected) << "'";
+  return success();
+}
+
+// A module marked with `cir.offload.container` holds the host module followed
+// by one or more device modules, each tagged with `cir.offload.kind`. Keeping
+// the host module first gives later offload passes a simple convention for
+// finding the host side while iterating the remaining device modules.
+static LogicalResult verifyOffloadContainer(mlir::Operation *op) {
+  auto container = mlir::dyn_cast<mlir::ModuleOp>(op);
+  if (!container)
+    return op->emitError() << "expects '"
+                           << cir::CIRDialect::getOffloadContainerAttrName()
+                           << "' attribute to be attached to '"
+                           << mlir::ModuleOp::getOperationName() << "'";
+
+  mlir::Block &body = *container.getBody();
+  if (body.empty())
+    return container.emitOpError()
+           << "expects host module as the first nested op";
+
+  auto host = mlir::dyn_cast<mlir::ModuleOp>(body.front());
+  if (!host)
+    return container.emitOpError()
+           << "expects host module as the first nested op";
+  if (failed(verifyOffloadKind(host, cir::OffloadKind::Host)))
+    return failure();
+
+  auto it = body.begin();
+  ++it;
----------------
xlauko wrote:

use `llvm::drop_begin(body)`

https://github.com/llvm/llvm-project/pull/206576