Function codegen sorta works

src/compilation.rs

@@ -5,7 +5,7 @@ use std::collections::HashMap;
 use self::llvm_sys::prelude::*;
 use self::llvm_sys::{LLVMIntPredicate, LLVMRealPredicate};
 
-use parser::{AST, Statement, Function, Expression, BinOp};
+use parser::{AST, Statement, Function, Prototype, Expression, BinOp};
 
 use llvm_wrap as LLVMWrap;
 
@@ -60,7 +60,7 @@ fn compile_ast(ast: AST, filename: &str) {
     let builder = LLVMWrap::CreateBuilderInContext(context);
 
     let program_return_type = LLVMWrap::Int64TypeInContext(context);
-    let main_function_type = LLVMWrap::FunctionType(program_return_type, &Vec::new(), false);
+    let main_function_type = LLVMWrap::FunctionType(program_return_type, Vec::new(), false);
     let main_function: LLVMValueRef = LLVMWrap::AddFunction(module, "main", main_function_type);
 
     let mut data = CompilationData {
@@ -116,9 +116,15 @@ impl CodeGen for Statement {
 
 impl CodeGen for Function {
     fn codegen(&self, data: &mut CompilationData) -> LLVMValueRef {
+
+        let function = self.prototype.codegen(data);
         let ref body = self.body;
-        let int_type = LLVMWrap::Int64TypeInContext(data.context);
-        let mut ret = LLVMWrap::ConstInt(int_type, 0, false);
+
+        let return_type = LLVMWrap::Int64TypeInContext(data.context);
+        let mut ret = LLVMWrap::ConstInt(return_type, 0, false);
+
+        println!("Getting here");
+
         for expr in body {
             ret = expr.codegen(data);
         }
@@ -126,6 +132,29 @@ impl CodeGen for Function {
     }
 }
 
+impl CodeGen for Prototype {
+    fn codegen(&self, data: &mut CompilationData) -> LLVMValueRef {
+        let num_args = self.parameters.len();
+        let return_type = LLVMWrap::Int64TypeInContext(data.context);
+        let mut arguments: Vec<LLVMTypeRef> = vec![];
+
+        for _ in 0..num_args {
+            arguments.push(LLVMWrap::Int64TypeInContext(data.context));
+        }
+        
+        let function_type =
+            LLVMWrap::FunctionType(return_type,
+                                   arguments,
+                                   false);
+
+        let function = LLVMWrap::AddFunction(data.module,
+                                             &*self.name,
+                                             function_type);
+
+        function
+    }
+}
+
 impl CodeGen for Expression {
     fn codegen(&self, data: &mut CompilationData) -> LLVMValueRef {
         use self::BinOp::*;

src/llvm_wrap.rs

@@ -34,20 +34,33 @@ pub fn AddFunction(module: LLVMModuleRef, name: &str, function_type: LLVMTypeRef
     unsafe { core::LLVMAddFunction(module, c_name.as_ptr(), function_type) }
 }
 
-// NOTE this is incomplete
 pub fn FunctionType(return_type: LLVMTypeRef,
-                    param_types: &[LLVMTypeRef],
+                    mut param_types: Vec<LLVMTypeRef>,
                     is_var_rag: bool)
                     -> LLVMTypeRef {
     let len = param_types.len();
     unsafe {
+        let pointer = param_types.as_mut_ptr();
         core::LLVMFunctionType(return_type,
-                               ptr::null_mut(),
+                               pointer,
                                len as u32,
                                if is_var_rag { 1 } else { 0 })
     }
 }
 
+pub fn GetNamedFunction(module: LLVMModuleRef,
+                        name: &str) -> Option<LLVMValueRef> {
+
+    let c_name = CString::new(name).unwrap();
+    let ret = unsafe { core::LLVMGetNamedFunction(module, c_name.as_ptr()) };
+
+    if ret.is_null() {
+        None
+    } else {
+        Some(ret)
+    }
+}
+
 pub fn VoidTypeInContext(context: LLVMContextRef) -> LLVMTypeRef {
     unsafe { core::LLVMVoidTypeInContext(context) }
 }