fix(codegen): Convert pointer to actual type when passing by-value (P…

…LC-lang#1039)

We were missing an edge-case where an argument is passed into a function A by-ref (INOUT) which in turn is passed into a function B by-val (INPUT) which generated the following IR for a DINT array
```
%call = call i32 @function1(i32 %load_x)` // we want `@function1([5 x i32] %load_x)` however
```
This commit fixes it, in that the commented IR is generated - specifically before passing the argument into function B it is bit-cast into its actual type.

src/codegen/generators/expression_generator.rs

@@ -168,6 +168,7 @@ impl<'ink, 'b> ExpressionCodeGenerator<'ink, 'b> {
             // we trust that the validator only passed us valid parameters (so left & right should be same type)
             return self.generate_expression(statement);
         }
+
         let v = self
             .generate_expression_value(expression)?
             .as_r_value(self.llvm, self.get_load_name(expression))
@@ -763,12 +764,48 @@ impl<'ink, 'b> ExpressionCodeGenerator<'ink, 'b> {
         type_name: &str,
         param_statement: &AstNode,
     ) -> Result<BasicValueEnum<'ink>, Diagnostic> {
-        Ok(match self.index.find_effective_type_by_name(type_name) {
-            Some(type_info) if type_info.information.is_string() => {
-                self.generate_string_argument(type_info, param_statement)?
+        let Some(type_info) = self.index.find_effective_type_by_name(type_name) else {
+            return self.generate_expression(param_statement);
+        };
+
+        if type_info.is_string() {
+            return self.generate_string_argument(type_info, param_statement);
+        }
+
+        // https://github.com/PLC-lang/rusty/issues/1037:
+        // This if-statement covers the case where we want to convert a pointer into its actual
+        // type, e.g. if an argument is passed into a function A by-ref (INOUT) which in turn is
+        // passed into another function B by-val (INPUT) then the pointer argument in function A has
+        // to be bit-cast into its actual type before passing it into function B.
+        if type_info.is_aggregate_type() && !type_info.is_vla() {
+            let deref = self.generate_expression_value(param_statement)?;
+
+            if deref.get_basic_value_enum().is_pointer_value() {
+                let ty = self.llvm_index.get_associated_type(type_name)?;
+                let cast = self.llvm.builder.build_bitcast(
+                    deref.get_basic_value_enum(),
+                    ty.ptr_type(AddressSpace::from(ADDRESS_SPACE_GENERIC)),
+                    "",
+                );
+
+                let load = self.llvm.builder.build_load(
+                    cast.into_pointer_value(),
+                    &self.get_load_name(param_statement).unwrap_or_default(),
+                );
+
+                if let Some(target_ty) = self.annotations.get_type_hint(param_statement, self.index) {
+                    let actual_ty = self.annotations.get_type_or_void(param_statement, self.index);
+                    let annotation = self.annotations.get(param_statement);
+
+                    return Ok(cast_if_needed!(self, target_ty, actual_ty, load, annotation));
+                }
+
+                return Ok(load);
             }
-            _ => self.generate_expression(param_statement)?,
-        })
+        }
+
+        // Fallback
+        self.generate_expression(param_statement)
     }
 
     /// Before passing a string to a function, it is copied to a new string with the

src/codegen/tests/function_tests.rs

@@ -370,3 +370,36 @@ fn return_variable_in_nested_call() {
     // we want a call passing the return-variable as apointer (actually the adress as a LWORD)
     insta::assert_snapshot!(codegen(src));
 }
+
+#[test]
+fn argument_fed_by_ref_then_by_val() {
+    let result = codegen(
+        "
+        TYPE MyType : ARRAY[1..5] OF DWORD; END_TYPE
+
+        FUNCTION main : DINT
+            VAR
+                arr : MyType;
+            END_VAR
+
+            fn_by_ref(arr);
+        END_FUNCTION
+
+        FUNCTION fn_by_ref : DINT
+            VAR_IN_OUT
+                arg_by_ref : MyType;
+            END_VAR
+
+            fn_by_val(arg_by_ref);
+        END_FUNCTION
+
+        FUNCTION fn_by_val : DINT
+            VAR_INPUT
+                arg_by_val : MyType;
+            END_VAR
+        END_FUNCTION
+    ",
+    );
+
+    insta::assert_snapshot!(result)
+}

src/codegen/tests/snapshots/rusty__codegen__tests__function_tests__argument_fed_by_ref_then_by_val.snap

@@ -0,0 +1,49 @@
+---
+source: src/codegen/tests/function_tests.rs
+expression: result
+---
+; ModuleID = 'main'
+source_filename = "main"
+
+define i32 @main() {
+entry:
+  %main = alloca i32, align 4
+  %arr = alloca [5 x i32], align 4
+  %0 = bitcast [5 x i32]* %arr to i8*
+  call void @llvm.memset.p0i8.i64(i8* align 1 %0, i8 0, i64 ptrtoint ([5 x i32]* getelementptr ([5 x i32], [5 x i32]* null, i32 1) to i64), i1 false)
+  store i32 0, i32* %main, align 4
+  %1 = bitcast [5 x i32]* %arr to i32*
+  %call = call i32 @fn_by_ref(i32* %1)
+  %main_ret = load i32, i32* %main, align 4
+  ret i32 %main_ret
+}
+
+define i32 @fn_by_ref(i32* %0) {
+entry:
+  %fn_by_ref = alloca i32, align 4
+  %arg_by_ref = alloca i32*, align 8
+  store i32* %0, i32** %arg_by_ref, align 8
+  store i32 0, i32* %fn_by_ref, align 4
+  %deref = load i32*, i32** %arg_by_ref, align 8
+  %1 = bitcast i32* %deref to [5 x i32]*
+  %load_arg_by_ref = load [5 x i32], [5 x i32]* %1, align 4
+  %call = call i32 @fn_by_val([5 x i32] %load_arg_by_ref)
+  %fn_by_ref_ret = load i32, i32* %fn_by_ref, align 4
+  ret i32 %fn_by_ref_ret
+}
+
+define i32 @fn_by_val([5 x i32] %0) {
+entry:
+  %fn_by_val = alloca i32, align 4
+  %arg_by_val = alloca [5 x i32], align 4
+  store [5 x i32] %0, [5 x i32]* %arg_by_val, align 4
+  store i32 0, i32* %fn_by_val, align 4
+  %fn_by_val_ret = load i32, i32* %fn_by_val, align 4
+  ret i32 %fn_by_val_ret
+}
+
+; Function Attrs: argmemonly nofree nounwind willreturn writeonly
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg) #0
+
+attributes #0 = { argmemonly nofree nounwind willreturn writeonly }
+

src/typesystem.rs

@@ -176,6 +176,10 @@ impl DataType {
         self.get_type_information().is_aggregate()
     }
 
+    pub fn is_string(&self) -> bool {
+        self.get_type_information().is_string()
+    }
+
     pub fn get_nature(&self) -> TypeNature {
         self.nature
     }

tests/correctness/functions.rs

@@ -1243,3 +1243,56 @@ fn sizeof_len() {
 
     assert_eq!(13, res);
 }
+
+#[test]
+fn argument_passed_by_ref_then_by_val() {
+    #[repr(C)]
+    struct MainType {
+        arr: [i32; 5],
+    }
+
+    let source = r"
+    TYPE MyType : ARRAY[1..5] OF DINT; END_TYPE
+
+    PROGRAM main
+        VAR
+            arr : MyType;
+        END_VAR
+
+        fn_by_ref(arr);
+    END_PROGRAM
+
+    FUNCTION fn_by_ref : DINT
+        VAR_IN_OUT
+            arg_by_ref : MyType;
+        END_VAR
+
+        // These SHOULD modify the underlying array passed from main
+        arg_by_ref[1] := 1;
+        arg_by_ref[2] := 2;
+        arg_by_ref[3] := 3;
+        arg_by_ref[4] := 4;
+        arg_by_ref[5] := 5;
+
+        fn_by_val(arg_by_ref);
+    END_FUNCTION
+
+    FUNCTION fn_by_val : DINT
+        VAR_INPUT
+            arg_by_val : MyType;
+        END_VAR
+
+        // These should NOT modify the underlying array passed from main
+        arg_by_val[1] := 10;
+        arg_by_val[2] := 20;
+        arg_by_val[3] := 30;
+        arg_by_val[4] := 40;
+        arg_by_val[5] := 50;
+    END_FUNCTION
+    ";
+
+    let mut maintype = MainType { arr: [0; 5] };
+    let _: i32 = compile_and_run(source, &mut maintype);
+
+    assert_eq!(maintype.arr, [1, 2, 3, 4, 5]);
+}