[MLIR][SPIRV] Create new ctx for deserialization in roundtrips.

[ergawy]

Summary

Roundtripping SPIR-V modules used the same MLIRContext object for both
ways of the trip. This resulted in deserialization using a context
object already containing Types constructed during serialization.
This commit rectifies that by creating a new MLIRContext during
deserialization.

[ergawy]

Failures seem totally unrelated.

[ergawy]

Rebase.

[mravishankar]

Thanks! It looks good to me, but I am not super familiar with the registration stuff, but looks fine overall.

@mehdi_amini PTAL.

[ergawy]

Thanks @mravishankar for the approval. If there are no doubts about the registration part can you please commit on my behalf? I don't have commit access.

[antiagainst]

Looks good to me. Thanks for fixing this!

mlir/lib/Dialect/SPIRV/Serialization/TranslateRegistration.cpp

if (spirvModules.begin() == spirvModules.end())
     return srcModule.emitError("found no 'spv.module' op");
 
   if (std::next(spirvModules.begin()) != spirvModules.end())
     return srcModule.emitError("found more than one 'spv.module' op");
 
   if (failed(spirv::serialize(*spirvModules.begin(), binary, emitDebugInfo)))
     return failure();
 
+  MLIRContext deserializationContext(false);
+  context->getDialectRegistry().loadAll(&deserializationContext);
   // Then deserialize to get back a SPIR-V module.
-  spirv::OwningSPIRVModuleRef spirvModule = spirv::deserialize(binary, context);
+  spirv::OwningSPIRVModuleRef spirvModule =
+      spirv::deserialize(binary, &deserializationContext);
   if (!spirvModule)
     return failure();
 
   // Wrap around in a new MLIR module.
   OwningModuleRef dstModule(ModuleOp::create(FileLineColLoc::get(
-      /*filename=*/"", /*line=*/0, /*column=*/0, context)));
+      /*filename=*/"", /*line=*/0, /*column=*/0, &deserializationContext)));
   dstModule->getBody()->push_front(spirvModule.release());
   dstModule->print(output);
 
   return mlir::success();
 }
 
 namespace mlir {
 void registerTestRoundtripSPIRV() {