[mlir][lldb] Fix several gcc warnings in mlir and lldb

[stella.stamenova]

Summary

These warnings are raised when compiling with gcc due to either having too few or too many commas, or in the case of lldb, the possibility of a nullptr.

[shafik]

lldb change LGTM

[teemperor]

lldb/source/Commands/CommandObjectTrace.cpp

119

Do you still have that GCC warning around (or the GCC version that produced that warning)? I'm kinda curious what GCC is assuming here. The interface never returns a "null" shared_ptr, the shared_ptr either contains a valid object or llvm::Error is returned. IIRC the Expected<ptr> return is the "new" version of how the Plugin interface should work (the old was just a ptr with nullptr being an error), so if some GCC version doesn't understand the Expected<ptr> pattern then we should maybe have some more centralized workaround instead of adding all the unnecessary nullptr checks.

But that shouldn't block this patch, so feel free to land.

[stella.stamenova]

lldb/source/Commands/CommandObjectTrace.cpp

119

The gcc version is:

gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0

The warning is:

/mnt/_work/9/s/llvm-project/lldb/source/Commands/CommandObjectTrace.cpp: In member function ‘virtual bool CommandObjectTraceLoad::DoExecute(lldb_private::Args&, lldb_private::CommandReturnObject&)’:
/mnt/_work/9/s/llvm-project/lldb/source/Commands/CommandObjectTrace.cpp:120:39: error: ‘%s’ directive argument is null [-Werror=format-overflow=]
  120 |         result.AppendMessageWithFormat("loading trace with plugin %s\n",
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  121 |                                        trace_sp->GetPluginName().AsCString());
      |                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/mnt/_work/9/s/llvm-project/lldb/source/Commands/CommandObjectTrace.cpp:120:39: error: ‘%s’ directive argument is null [-Werror=format-overflow=]

Interestingly, this is the only place in all of llvm (well, llvm, lld, clang and lldb) that produces this warning.

[teemperor]

lldb/source/Commands/CommandObjectTrace.cpp

119

Ah, the problem is that we call AsCString and because ConstString's API was literally developed in hell this function returns nullptr if the ConstString is empty (or the weird null state). I'm gonna make a patch.

lldb/source/Commands/CommandObjectTrace.cpp

llvm::Expected<json::Value> session_file =
         json::parse(buffer_or_error.get()->getBuffer().str());
     if (!session_file)
       return end_with_failure(session_file.takeError());
 
     if (Expected<lldb::TraceSP> traceOrErr =
             Trace::FindPlugin(GetDebugger(), *session_file,
                               json_file.GetDirectory().AsCString())) {
       lldb::TraceSP trace_sp = traceOrErr.get();
-      if (m_options.m_verbose)
+      if (m_options.m_verbose && trace_sp)
         result.AppendMessageWithFormat("loading trace with plugin %s\n",
                                        trace_sp->GetPluginName().AsCString());
     } else
       return end_with_failure(traceOrErr.takeError());
 
     result.SetStatus(eReturnStatusSuccessFinishResult);
     return true;
   }

mlir/lib/Conversion/VectorToSPIRV/VectorToSPIRV.cpp

 #include <numeric>
 
 using namespace mlir;
 
 /// Gets the first integer value from `attr`, assuming it is an integer array
 /// attribute.
 static uint64_t getFirstIntValue(ArrayAttr attr) {
   return (*attr.getAsValueRange<IntegerAttr>().begin()).getZExtValue();
-};
+}
 
 namespace {
 
 struct VectorBitcastConvert final
     : public OpConversionPattern<vector::BitCastOp> {
   using OpConversionPattern::OpConversionPattern;
 
   LogicalResult

mlir/tools/mlir-linalg-ods-gen/mlir-linalg-ods-yaml-gen.cpp

 };
 
 } // namespace
 
 //===----------------------------------------------------------------------===//
 // Mapping traits.
 //===----------------------------------------------------------------------===//
 
-LLVM_YAML_IS_SEQUENCE_VECTOR(LinalgTensorDef);
-LLVM_YAML_IS_SEQUENCE_VECTOR(SerializedAffineMap);
-LLVM_YAML_IS_SEQUENCE_VECTOR(LinalgIteratorTypeDef);
-LLVM_YAML_IS_SEQUENCE_VECTOR(ScalarAssign);
-LLVM_YAML_IS_SEQUENCE_VECTOR(ScalarExpression);
-LLVM_YAML_IS_DOCUMENT_LIST_VECTOR(LinalgOpConfig);
+LLVM_YAML_IS_SEQUENCE_VECTOR(LinalgTensorDef)
+LLVM_YAML_IS_SEQUENCE_VECTOR(SerializedAffineMap)
+LLVM_YAML_IS_SEQUENCE_VECTOR(LinalgIteratorTypeDef)
+LLVM_YAML_IS_SEQUENCE_VECTOR(ScalarAssign)
+LLVM_YAML_IS_SEQUENCE_VECTOR(ScalarExpression)
+LLVM_YAML_IS_DOCUMENT_LIST_VECTOR(LinalgOpConfig)
 
 namespace llvm {
 namespace yaml {
 
 /// Top-level type containing op metadata and one of a concrete op type.
 /// Currently, the only defined op type is `structured_op` (maps to
 /// `LinalgStructuredOpConfig`).
 template <>