Catch MLIR ukernel parsing errors (#22353)

MLIR ukernels are lazily parsed when used. When they fail to parse, this
was manifesting itself as a compiler crash (null dereference) here:

https://github.com/iree-org/iree/blob/59ce62fd8a3686c45d00bfce197cd15f38697f0d/compiler/plugins/target/ROCM/Dialect/ROCM/Transforms/ApplyBuiltinPDLPatterns.cpp#L354
as in that case, `builtinModule.get()` is null.

This PR reports an op error when parsing failed, so the code doesn't
reach this place anymroe and the crash is avoided.

To make the parser's internal diagnostics themselves more helpful, this
PR also passes a `sourceName` argument to `parseSourceString` so that
they now directly refer to a meaningful location in the MLIR ukernel
files.

---------

Signed-off-by: Benoit Jacob <[email protected]>

Author: bjacob

compiler/plugins/target/ROCM/Dialect/ROCM/Transforms/ApplyBuiltinPDLPatterns.cpp

@@ -341,15 +341,21 @@ class ApplyBuiltinPDLPatternsDriverPass final
       if (ukernelSymbols.contains(ukernelDesc.getUkernelName())) {
         return WalkResult::advance();
       }
+      std::string builtinNameStr = builtinName.str();
       std::optional<StringRef> maybeBuiltin =
-          rocmDialect->getBuiltin(builtinName.str());
+          rocmDialect->getBuiltin(builtinNameStr);
       if (!maybeBuiltin) {
         moduleOp.emitOpError()
-            << "could not find builtin with name " << builtinName.str();
+            << "could not find builtin module with name " << builtinNameStr;
+        return WalkResult::interrupt();
+      }
+      OwningOpRef<ModuleOp> builtinModule = parseSourceString<ModuleOp>(
+          *maybeBuiltin, ctx, /*sourceName=*/builtinNameStr);
+      if (!builtinModule) {
+        moduleOp.emitOpError()
+            << "failed to parse builtin module with name " << builtinNameStr;
         return WalkResult::interrupt();
       }
-      OwningOpRef<ModuleOp> builtinModule =
-          parseSourceString<ModuleOp>(*maybeBuiltin, ctx);
       Operation *symbolTableOp =
           SymbolTable::getNearestSymbolTable(builtinModule.get());
       SymbolTable symbolTable(symbolTableOp);