Refactor: Simply negate for unsigned unary minus

It seems negation internally uses 2's complement.

Refactor: LLVM: Combine visit_IntegerUnaryMinus() and visit_UnsignedIntegerUnaryMinus()

Author: ubaidsk

src/libasr/codegen/asr_to_llvm.cpp

@@ -5345,7 +5345,8 @@ class ASRToLLVMVisitor : public ASR::BaseVisitor<ASRToLLVMVisitor>
         tmp = builder->CreateNot(tmp);
     }
 
-    void visit_IntegerUnaryMinus(const ASR::IntegerUnaryMinus_t &x) {
+    template <typename T>
+    void handle_SU_IntegerUnaryMinus(const T& x) {
         if (x.m_value) {
             this->visit_expr_wrapper(x.m_value, true);
             return;
@@ -5356,15 +5357,12 @@ class ASRToLLVMVisitor : public ASR::BaseVisitor<ASRToLLVMVisitor>
         tmp = builder->CreateSub(zero, tmp);
     }
 
+    void visit_IntegerUnaryMinus(const ASR::IntegerUnaryMinus_t &x) {
+        handle_SU_IntegerUnaryMinus(x);
+    }
+
     void visit_UnsignedIntegerUnaryMinus(const ASR::UnsignedIntegerUnaryMinus_t &x) {
-        if (x.m_value) {
-            this->visit_expr_wrapper(x.m_value, true);
-            return;
-        }
-        this->visit_expr_wrapper(x.m_arg, true);
-        int kind = ASRUtils::extract_kind_from_ttype_t(ASRUtils::expr_type(x.m_arg));
-        llvm::Value *one = llvm::ConstantInt::get(context, llvm::APInt(kind * 8, 1, true));
-        tmp = builder->CreateAdd(builder->CreateNot(tmp), one); // compute 2's complement
+        handle_SU_IntegerUnaryMinus(x);
     }
 
     void visit_RealUnaryMinus(const ASR::RealUnaryMinus_t &x) {

src/lpython/semantics/python_ast_to_asr.cpp

@@ -3602,9 +3602,8 @@ class CommonVisitor : public AST::BaseVisitor<Struct> {
                 if (ASRUtils::expr_value(operand) != nullptr) {
                     int64_t op_value = ASR::down_cast<ASR::UnsignedIntegerConstant_t>(
                                             ASRUtils::expr_value(operand))->m_n;
-                    op_value = (~op_value) + 1; // compute 2's complement
                     value = ASR::down_cast<ASR::expr_t>(ASR::make_UnsignedIntegerConstant_t(
-                        al, x.base.base.loc, op_value, operand_type));
+                        al, x.base.base.loc, -op_value, operand_type));
                 }
                 tmp = ASR::make_UnsignedIntegerUnaryMinus_t(al, x.base.base.loc, operand,
                                                     operand_type, value);