Problem with FuseOps (and embedded constants in TIR)

manupa-arm · February 25, 2022, 9:51am

Sorry to hear that there was downstream failure because of #8509.

I am also wondering how this is true, because of the following (note that we just used what was supported in TVM via LinkedParam node) :

github.com/apache/tvm

src/target/llvm/codegen_params.cc

dcbdeddba


      
          case runtime::DataType::TypeCode::kFloat:
            switch (arr_type.bits()) {
              case 16:
                // NOTE: float16 is treated as uint16_t.
                element_type = llvm::Type::getIntNTy(*ctx, arr_type.bits());
                BuildLLVMVector<uint16_t>(element_type, arr->data, num_elements, &elements);
                break;
              case 32:
                element_type = llvm::Type::getFloatTy(*ctx);
                BuildLLVMVector<float>(element_type, arr->data, num_elements, &elements);
                break;
              case 64:
                element_type = llvm::Type::getDoubleTy(*ctx);
                BuildLLVMVector<double>(element_type, arr->data, num_elements, &elements);
                break;
              default:
                CHECK(false) << "CodegenParams: only support 32- or 64-bit floating point; saw "
                             << arr_type.bits() << "-bit array";
                break;
            }
            break;

github.com/apache/tvm

src/target/source/codegen_params.cc

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          case runtime::DataType::TypeCode::kFloat: {
            os.fill(' ');
            os.setf(std::ios::left, std::ios::adjustfield);
            if (arr_type.bits() == 16) {
              // NOTE: print types not widely supported by C as uint16_t.
              PrintIntegralArray<uint16_t>(arr->data, num_elements, indent_chars, os);
            } else if (arr_type.bits() == 32) {
              PrintFloatingPointArray<float>(arr->data, num_elements, indent_chars, os);
            } else if (arr_type.bits() == 64) {
              PrintFloatingPointArray<double>(arr->data, num_elements, indent_chars, os);
            } else {
              CHECK(false) << "CodegenParams: only support 32- or 64-bit floating point; saw "
                           << arr_type.bits() << "-bit array";
            }
            break;
          }

The above are called respectively in the following locations :

github.com/apache/tvm

src/target/llvm/codegen_llvm.cc

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              builder_->CreateCondBr(cond, then_block, end_block, md_very_likely_branch_);
              builder_->SetInsertPoint(then_block);
              this->VisitStmt(op->then_case);
              builder_->CreateBr(end_block);
            }
            builder_->SetInsertPoint(end_block);
          }
          
          void CodeGenLLVM::VisitStmt_(const AllocateConstNode* op) {
            auto data = op->data.value();
            auto array = NDArrayToLLVMArray(ctx_, data);
            std::string symbol_name = op->buffer_var->name_hint;
            llvm::GlobalVariable* param_symbol = new llvm::GlobalVariable(
                *module_, array->getType(), true, llvm::GlobalValue::InternalLinkage, array, symbol_name);
          
            var_map_[op->buffer_var.operator->()] = param_symbol;
            this->VisitStmt(op->body);
          }
          
          void CodeGenLLVM::VisitStmt_(const AllocateNode* op) {
            ICHECK(!is_zero(op->condition));

github.com/apache/tvm

src/target/source/codegen_c.cc

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                        << "extern \"C\" {\n"
                        << "#endif\n"
                        << "static const ";
          
            PrintType(data.DataType(), decl_stream);
          
            // Allocate the global static variable
            decl_stream << " __attribute__((section(\".rodata.tvm\"), "
                        << "aligned(" << constants_byte_alignment_->value << "))) " << symbol_name << "["
                        << num_elements << "] = {\n";
            NDArrayDataToC(data, 4, decl_stream);
          
            decl_stream << "};\n"
                        << "#ifdef __cplusplus\n"
                        << "}  // extern \"C\"\n"
                        << "#endif\n";
            var_idmap_[op->buffer_var.operator->()] = symbol_name;
            this->PrintStmt(op->body);
          }
          
          void CodeGenC::VisitExpr_(const LoadNode* op, std::ostream& os) {  // NOLINT(*)

We need to fix this if it is not happenning. @kparzysz would you be able to file an issue ? attn : @dmitriy-arm @Mousius

I think we need to move the link-params to be a property of the TIR backend (i.e. target).

However, the above seems to be the workaround of the issue, the real issue I suspect is hexagon backend expect LinkedParams node if --link-params is used, however, there is not a unit test (a simple codegen one) to assert this – that should have been broken by #8509.