llvm: split into sub-modules

8 files changed, 682 insertions, 606 deletions

diff --git a/src/codegen.rs b/src/codegen.rs
index 0a7893e..08c3039 100644
--- a/src/codegen.rs
+++ b/src/codegen.rs
@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 
-use crate::llvm::{Builder, FnValue, FunctionPassManager, Module, Value};
+use crate::llvm::{FnValue, FunctionPassManager, IRBuilder, Module, Value};
 use crate::parser::{ExprAST, FunctionAST, PrototypeAST};
 use crate::Either;
 
@@ -9,7 +9,7 @@ type CodegenResult<T> = Result<T, String>;
 /// Code generator from kaleidoscope AST to LLVM IR.
 pub struct Codegen<'llvm, 'a> {
     module: &'llvm Module,
-    builder: &'a Builder<'llvm>,
+    builder: &'a IRBuilder<'llvm>,
     fpm: &'a FunctionPassManager<'llvm>,
 }
 
@@ -21,7 +21,7 @@ impl<'llvm, 'a> Codegen<'llvm, 'a> {
     ) -> CodegenResult<FnValue<'llvm>> {
         let cg = Codegen {
             module,
-            builder: &Builder::with_ctx(module),
+            builder: &IRBuilder::with_ctx(module),
             fpm: &FunctionPassManager::with_ctx(module),
         };
         let mut variables = HashMap::new();
@@ -129,7 +129,10 @@ impl<'llvm, 'a> Codegen<'llvm, 'a> {
         if let Ok(ret) = self.codegen_expr(body, named_values) {
             self.builder.ret(ret);
             assert!(the_function.verify());
+
+            // Run the optimization passes on the function.
             self.fpm.run(the_function);
+
             Ok(the_function)
         } else {
             todo!("Failed to codegen function body, erase from module!");
diff --git a/src/llvm.rs b/src/llvm.rs
deleted file mode 100644
index 5598cd4..0000000
--- a/src/llvm.rs
+++ /dev/null
@@ -1,603 +0,0 @@
-//! Safe wrapper around the LLVM C API.
-//!
-//! References returned from the LLVM API are tied to the `'llvm` lifetime which is bound to the
-//! context where the objects are created in.
-//! We do not offer wrappers to remove or delete any objects in the context and therefore all the
-//! references will be valid for the liftime of the context.
-
-use llvm_sys::analysis::{LLVMVerifierFailureAction, LLVMVerifyFunction};
-use llvm_sys::core::{
-    LLVMAddFunction, LLVMAppendBasicBlockInContext, LLVMBuildFAdd, LLVMBuildFCmp, LLVMBuildFMul,
-    LLVMBuildFSub, LLVMBuildRet, LLVMBuildUIToFP, LLVMConstReal, LLVMContextCreate,
-    LLVMContextDispose, LLVMCountBasicBlocks, LLVMCountParams, LLVMCreateBuilderInContext,
-    LLVMCreateFunctionPassManagerForModule, LLVMDisposeBuilder, LLVMDisposeModule,
-    LLVMDisposePassManager, LLVMDoubleTypeInContext, LLVMDumpModule, LLVMDumpType, LLVMDumpValue,
-    LLVMGetNamedFunction, LLVMGetParam, LLVMGetReturnType, LLVMGetTypeKind, LLVMGetValueKind,
-    LLVMGetValueName2, LLVMInitializeFunctionPassManager, LLVMModuleCreateWithNameInContext,
-    LLVMPositionBuilderAtEnd, LLVMRunFunctionPassManager, LLVMSetValueName2, LLVMTypeOf,
-};
-use llvm_sys::prelude::{
-    LLVMBasicBlockRef, LLVMBool, LLVMBuilderRef, LLVMContextRef, LLVMModuleRef, LLVMPassManagerRef,
-    LLVMTypeRef, LLVMValueRef,
-};
-use llvm_sys::transforms::{
-    instcombine::LLVMAddInstructionCombiningPass,
-    scalar::{LLVMAddCFGSimplificationPass, LLVMAddNewGVNPass, LLVMAddReassociatePass},
-};
-use llvm_sys::{LLVMRealPredicate, LLVMTypeKind, LLVMValueKind};
-
-use std::convert::TryFrom;
-use std::ffi::CStr;
-use std::marker::PhantomData;
-use std::ops::Deref;
-
-use crate::SmallCStr;
-
-// Definition of LLVM C API functions using our `repr(transparent)` types.
-extern "C" {
-    fn LLVMFunctionType(
-        ReturnType: Type<'_>,
-        ParamTypes: *mut Type<'_>,
-        ParamCount: ::libc::c_uint,
-        IsVarArg: LLVMBool,
-    ) -> LLVMTypeRef;
-    fn LLVMBuildCall2(
-        arg1: LLVMBuilderRef,
-        arg2: Type<'_>,
-        Fn: FnValue<'_>,
-        Args: *mut Value<'_>,
-        NumArgs: ::libc::c_uint,
-        Name: *const ::libc::c_char,
-    ) -> LLVMValueRef;
-}
-
-// ====================
-//   Module / Context
-// ====================
-
-/// Wrapper for a LLVM Module with its own LLVM Context.
-pub struct Module {
-    ctx: LLVMContextRef,
-    module: LLVMModuleRef,
-}
-
-impl<'llvm> Module {
-    /// Create a new Module instance.
-    ///
-    /// # Panics
-    ///
-    /// Panics if creating the context or the module fails.
-    pub fn new() -> Self {
-        let (ctx, module) = unsafe {
-            let c = LLVMContextCreate();
-            let m = LLVMModuleCreateWithNameInContext(b"module\0".as_ptr().cast(), c);
-            assert!(!c.is_null() && !m.is_null());
-            (c, m)
-        };
-
-        Module { ctx, module }
-    }
-
-    /// Dump LLVM IR emitted into the Module to stdout.
-    pub fn dump(&self) {
-        unsafe { LLVMDumpModule(self.module) };
-    }
-
-    /// Get a type reference representing a `f64` float.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn type_f64(&self) -> Type<'llvm> {
-        let type_ref = unsafe { LLVMDoubleTypeInContext(self.ctx) };
-        Type::new(type_ref)
-    }
-
-    /// Get a type reference representing a `fn(args) -> ret` function.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn type_fn(&'llvm self, args: &mut [Type<'llvm>], ret: Type<'llvm>) -> Type<'llvm> {
-        let type_ref = unsafe {
-            LLVMFunctionType(
-                ret,
-                args.as_mut_ptr(),
-                args.len() as libc::c_uint,
-                0, /* IsVarArg */
-            )
-        };
-        Type::new(type_ref)
-    }
-
-    /// Add a function with the given `name` and `fn_type` to the module and return a value
-    /// reference representing the function.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer or `name` could not be converted to a
-    /// [`SmallCStr`].
-    pub fn add_fn(&'llvm self, name: &str, fn_type: Type<'llvm>) -> FnValue<'llvm> {
-        debug_assert_eq!(
-            fn_type.kind(),
-            LLVMTypeKind::LLVMFunctionTypeKind,
-            "Expected a function type when adding a function!"
-        );
-
-        let name = SmallCStr::try_from(name)
-            .expect("Failed to convert 'name' argument to small C string!");
-
-        let value_ref = unsafe { LLVMAddFunction(self.module, name.as_ptr(), fn_type.0) };
-        FnValue::new(value_ref)
-    }
-
-    /// Get a function value reference to the function with the given `name` if it was previously
-    /// added to the module with [`add_fn`][Module::add_fn].
-    ///
-    /// # Panics
-    ///
-    /// Panics if `name` could not be converted to a [`SmallCStr`].
-    pub fn get_fn(&'llvm self, name: &str) -> Option<FnValue<'llvm>> {
-        let name = SmallCStr::try_from(name)
-            .expect("Failed to convert 'name' argument to small C string!");
-
-        let value_ref = unsafe { LLVMGetNamedFunction(self.module, name.as_ptr()) };
-
-        (!value_ref.is_null()).then(|| FnValue::new(value_ref))
-    }
-
-    /// Append a Basic Block to the end of the function referenced by the value reference
-    /// `fn_value`.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn append_basic_block(&'llvm self, fn_value: FnValue<'llvm>) -> BasicBlock<'llvm> {
-        let block = unsafe {
-            LLVMAppendBasicBlockInContext(
-                self.ctx,
-                fn_value.value_ref(),
-                b"block\0".as_ptr().cast(),
-            )
-        };
-        assert!(!block.is_null());
-
-        BasicBlock(block, PhantomData)
-    }
-}
-
-impl Drop for Module {
-    fn drop(&mut self) {
-        unsafe {
-            LLVMDisposeModule(self.module);
-            LLVMContextDispose(self.ctx);
-        }
-    }
-}
-
-// ===========
-//   Builder
-// ===========
-
-/// Wrapper for a LLVM IR Builder.
-pub struct Builder<'llvm> {
-    builder: LLVMBuilderRef,
-    _ctx: PhantomData<&'llvm ()>,
-}
-
-impl<'llvm> Builder<'llvm> {
-    /// Create a new LLVM IR Builder with the `module`s context.
-    ///
-    /// # Panics
-    ///
-    /// Panics if creating the IR Builder fails.
-    pub fn with_ctx(module: &'llvm Module) -> Builder<'llvm> {
-        let builder = unsafe { LLVMCreateBuilderInContext(module.ctx) };
-        assert!(!builder.is_null());
-
-        Builder {
-            builder,
-            _ctx: PhantomData,
-        }
-    }
-
-    /// Position the IR Builder at the end of the given Basic Block.
-    pub fn pos_at_end(&self, bb: BasicBlock<'llvm>) {
-        unsafe {
-            LLVMPositionBuilderAtEnd(self.builder, bb.0);
-        }
-    }
-
-    /// Emit a [fadd](https://llvm.org/docs/LangRef.html#fadd-instruction) instruction.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn fadd(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
-        debug_assert!(lhs.is_f64(), "fadd: Expected f64 as lhs operand!");
-        debug_assert!(rhs.is_f64(), "fadd: Expected f64 as rhs operand!");
-
-        let value_ref = unsafe {
-            LLVMBuildFAdd(
-                self.builder,
-                lhs.value_ref(),
-                rhs.value_ref(),
-                b"fadd\0".as_ptr().cast(),
-            )
-        };
-        Value::new(value_ref)
-    }
-
-    /// Emit a [fsub](https://llvm.org/docs/LangRef.html#fsub-instruction) instruction.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn fsub(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
-        debug_assert!(lhs.is_f64(), "fsub: Expected f64 as lhs operand!");
-        debug_assert!(rhs.is_f64(), "fsub: Expected f64 as rhs operand!");
-
-        let value_ref = unsafe {
-            LLVMBuildFSub(
-                self.builder,
-                lhs.value_ref(),
-                rhs.value_ref(),
-                b"fsub\0".as_ptr().cast(),
-            )
-        };
-        Value::new(value_ref)
-    }
-
-    /// Emit a [fmul](https://llvm.org/docs/LangRef.html#fmul-instruction) instruction.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn fmul(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
-        debug_assert!(lhs.is_f64(), "fmul: Expected f64 as lhs operand!");
-        debug_assert!(rhs.is_f64(), "fmul: Expected f64 as rhs operand!");
-
-        let value_ref = unsafe {
-            LLVMBuildFMul(
-                self.builder,
-                lhs.value_ref(),
-                rhs.value_ref(),
-                b"fmul\0".as_ptr().cast(),
-            )
-        };
-        Value::new(value_ref)
-    }
-
-    /// Emit a [fcmult](https://llvm.org/docs/LangRef.html#fcmp-instruction) instruction.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn fcmpult(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
-        debug_assert!(lhs.is_f64(), "fcmplt: Expected f64 as lhs operand!");
-        debug_assert!(rhs.is_f64(), "fcmplt: Expected f64 as rhs operand!");
-
-        let value_ref = unsafe {
-            LLVMBuildFCmp(
-                self.builder,
-                LLVMRealPredicate::LLVMRealULT,
-                lhs.value_ref(),
-                rhs.value_ref(),
-                b"fcmplt\0".as_ptr().cast(),
-            )
-        };
-        Value::new(value_ref)
-    }
-
-    /// Emit a [uitofp](https://llvm.org/docs/LangRef.html#uitofp-to-instruction) instruction.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn uitofp(&self, val: Value<'llvm>, dest_type: Type<'llvm>) -> Value<'llvm> {
-        debug_assert!(val.is_int(), "uitofp: Expected integer operand!");
-
-        let value_ref = unsafe {
-            LLVMBuildUIToFP(
-                self.builder,
-                val.value_ref(),
-                dest_type.0,
-                b"uitofp\0".as_ptr().cast(),
-            )
-        };
-        Value::new(value_ref)
-    }
-
-    /// Emit a [call](https://llvm.org/docs/LangRef.html#call-instruction) instruction.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn call(&self, fn_value: FnValue<'llvm>, args: &mut [Value<'llvm>]) -> Value<'llvm> {
-        let value_ref = unsafe {
-            LLVMBuildCall2(
-                self.builder,
-                fn_value.ret_type(),
-                fn_value,
-                args.as_mut_ptr(),
-                args.len() as libc::c_uint,
-                b"call\0".as_ptr().cast(),
-            )
-        };
-        Value::new(value_ref)
-    }
-
-    /// Emit a [ret](https://llvm.org/docs/LangRef.html#ret-instruction) instruction.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn ret(&self, ret: Value<'llvm>) {
-        let ret = unsafe { LLVMBuildRet(self.builder, ret.value_ref()) };
-        assert!(!ret.is_null());
-    }
-}
-
-impl Drop for Builder<'_> {
-    fn drop(&mut self) {
-        unsafe { LLVMDisposeBuilder(self.builder) }
-    }
-}
-
-// ==============
-//   BasicBlock
-// ==============
-
-/// Wrapper for a LLVM Basic Block.
-#[derive(Copy, Clone)]
-pub struct BasicBlock<'llvm>(LLVMBasicBlockRef, PhantomData<&'llvm ()>);
-
-// ========
-//   Type
-// ========
-
-/// Wrapper for a LLVM Type Reference.
-#[derive(Copy, Clone)]
-#[repr(transparent)]
-pub struct Type<'llvm>(LLVMTypeRef, PhantomData<&'llvm ()>);
-
-impl<'llvm> Type<'llvm> {
-    fn new(type_ref: LLVMTypeRef) -> Self {
-        assert!(!type_ref.is_null());
-        Type(type_ref, PhantomData)
-    }
-
-    fn kind(&self) -> LLVMTypeKind {
-        unsafe { LLVMGetTypeKind(self.0) }
-    }
-
-    /// Dump the LLVM Type to stdout.
-    pub fn dump(&self) {
-        unsafe { LLVMDumpType(self.0) };
-    }
-
-    /// Get a value reference representing the const `f64` value.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn const_f64(self, n: f64) -> Value<'llvm> {
-        debug_assert_eq!(
-            self.kind(),
-            LLVMTypeKind::LLVMDoubleTypeKind,
-            "Expected a double type when creating const f64 value!"
-        );
-
-        let value_ref = unsafe { LLVMConstReal(self.0, n) };
-        Value::new(value_ref)
-    }
-}
-
-// =========
-//   Value
-// =========
-
-/// Wrapper for a LLVM Value Reference.
-#[derive(Copy, Clone)]
-#[repr(transparent)]
-pub struct Value<'llvm>(LLVMValueRef, PhantomData<&'llvm ()>);
-
-impl<'llvm> Value<'llvm> {
-    fn new(value_ref: LLVMValueRef) -> Self {
-        assert!(!value_ref.is_null());
-        Value(value_ref, PhantomData)
-    }
-
-    #[inline]
-    fn value_ref(&self) -> LLVMValueRef {
-        self.0
-    }
-
-    fn kind(&self) -> LLVMValueKind {
-        unsafe { LLVMGetValueKind(self.value_ref()) }
-    }
-
-    /// Dump the LLVM Value to stdout.
-    pub fn dump(&self) {
-        unsafe { LLVMDumpValue(self.value_ref()) };
-    }
-
-    /// Get a type reference representing for the given value reference.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn type_of(&self) -> Type<'llvm> {
-        let type_ref = unsafe { LLVMTypeOf(self.value_ref()) };
-        Type::new(type_ref)
-    }
-
-    /// Set the name for the given value reference.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn set_name(&self, name: &str) {
-        unsafe { LLVMSetValueName2(self.value_ref(), name.as_ptr().cast(), name.len()) };
-    }
-
-    /// Get the name for the given value reference.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn get_name(&self) -> &'llvm str {
-        let name = unsafe {
-            let mut len: libc::size_t = 0;
-            let name = LLVMGetValueName2(self.0, &mut len as _);
-            assert!(!name.is_null());
-
-            CStr::from_ptr(name)
-        };
-
-        // TODO: Does this string live for the time of the LLVM context?!
-        name.to_str()
-            .expect("Expected valid UTF8 string from LLVM API")
-    }
-
-    /// Check if value is of `f64` type.
-    pub fn is_f64(&self) -> bool {
-        self.type_of().kind() == LLVMTypeKind::LLVMDoubleTypeKind
-    }
-
-    /// Check if value is of integer type.
-    pub fn is_int(&self) -> bool {
-        self.type_of().kind() == LLVMTypeKind::LLVMIntegerTypeKind
-    }
-}
-
-/// Wrapper for a LLVM Value Reference specialized for contexts where function values are needed.
-#[derive(Copy, Clone)]
-#[repr(transparent)]
-pub struct FnValue<'llvm>(Value<'llvm>);
-
-impl<'llvm> Deref for FnValue<'llvm> {
-    type Target = Value<'llvm>;
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl<'llvm> FnValue<'llvm> {
-    fn new(value_ref: LLVMValueRef) -> Self {
-        let value = Value::new(value_ref);
-        debug_assert_eq!(
-            value.kind(),
-            LLVMValueKind::LLVMFunctionValueKind,
-            "Expected a fn value when constructing FnValue!"
-        );
-
-        FnValue(value)
-    }
-
-    /// Get a type reference representing the return value of the given function value.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer.
-    pub fn ret_type(&self) -> Type<'llvm> {
-        let type_ref = unsafe { LLVMGetReturnType(LLVMTypeOf(self.value_ref())) };
-        Type::new(type_ref)
-    }
-
-    /// Get the number of function arguments for the given function value.
-    pub fn args(&self) -> usize {
-        unsafe { LLVMCountParams(self.value_ref()) as usize }
-    }
-
-    /// Get a value reference for the function argument at index `idx`.
-    ///
-    /// # Panics
-    ///
-    /// Panics if LLVM API returns a `null` pointer or indexed out of bounds.
-    pub fn arg(&self, idx: usize) -> Value<'llvm> {
-        assert!(idx < self.args());
-
-        let value_ref = unsafe { LLVMGetParam(self.value_ref(), idx as libc::c_uint) };
-        Value::new(value_ref)
-    }
-
-    /// Get the number of Basic Blocks for the given function value.
-    pub fn basic_blocks(&self) -> usize {
-        unsafe { LLVMCountBasicBlocks(self.value_ref()) as usize }
-    }
-
-    /// Verify that the given function is valid.
-    pub fn verify(&self) -> bool {
-        unsafe {
-            LLVMVerifyFunction(
-                self.value_ref(),
-                LLVMVerifierFailureAction::LLVMPrintMessageAction,
-            ) == 0
-        }
-    }
-}
-
-// =======================
-//   FunctionPassManager
-// =======================
-
-/// Wrapper for a LLVM Function PassManager (legacy).
-pub struct FunctionPassManager<'llvm> {
-    fpm: LLVMPassManagerRef,
-    _ctx: PhantomData<&'llvm ()>,
-}
-
-impl<'llvm> FunctionPassManager<'llvm> {
-    /// Create a new Function PassManager with the following optimization passes
-    /// - InstructionCombiningPass
-    /// - ReassociatePass
-    /// - NewGVNPass
-    /// - CFGSimplificationPass
-    ///
-    /// The list of selected optimization passes is taken from the tutorial chapter [LLVM
-    /// Optimization Passes](https://llvm.org/docs/tutorial/MyFirstLanguageFrontend/LangImpl04.html#id3).
-    pub fn with_ctx(module: &'llvm Module) -> FunctionPassManager<'llvm> {
-        let fpm = unsafe {
-            // Borrows module reference.
-            LLVMCreateFunctionPassManagerForModule(module.module)
-        };
-        assert!(!fpm.is_null());
-
-        unsafe {
-            // Do simple "peephole" optimizations and bit-twiddling optzns.
-            LLVMAddInstructionCombiningPass(fpm);
-            // Reassociate expressions.
-            LLVMAddReassociatePass(fpm);
-            // Eliminate Common SubExpressions.
-            LLVMAddNewGVNPass(fpm);
-            // Simplify the control flow graph (deleting unreachable blocks, etc).
-            LLVMAddCFGSimplificationPass(fpm);
-
-            let fail = LLVMInitializeFunctionPassManager(fpm);
-            assert_eq!(fail, 0);
-        }
-
-        FunctionPassManager {
-            fpm,
-            _ctx: PhantomData,
-        }
-    }
-
-    /// Run the optimization passes registered with the Function PassManager on the function
-    /// referenced by `fn_value`.
-    pub fn run(&'llvm self, fn_value: FnValue<'llvm>) {
-        unsafe {
-            // Returns 1 if any of the passes modified the function, false otherwise.
-            LLVMRunFunctionPassManager(self.fpm, fn_value.value_ref());
-        }
-    }
-}
-
-impl Drop for FunctionPassManager<'_> {
-    fn drop(&mut self) {
-        unsafe {
-            LLVMDisposePassManager(self.fpm);
-        }
-    }
-}
diff --git a/src/llvm/builder.rs b/src/llvm/builder.rs
new file mode 100644
index 0000000..3d43b68
--- /dev/null
+++ b/src/llvm/builder.rs
@@ -0,0 +1,189 @@
+use llvm_sys::{
+    core::{
+        LLVMBuildFAdd, LLVMBuildFCmp, LLVMBuildFMul, LLVMBuildFSub, LLVMBuildRet, LLVMBuildUIToFP,
+        LLVMCreateBuilderInContext, LLVMDisposeBuilder, LLVMPositionBuilderAtEnd,
+    },
+    prelude::{LLVMBuilderRef, LLVMValueRef},
+    LLVMRealPredicate,
+};
+
+use std::marker::PhantomData;
+
+use super::{BasicBlock, FnValue, Module, Type, Value};
+
+// Definition of LLVM C API functions using our `repr(transparent)` types.
+extern "C" {
+    fn LLVMBuildCall2(
+        arg1: LLVMBuilderRef,
+        arg2: Type<'_>,
+        Fn: FnValue<'_>,
+        Args: *mut Value<'_>,
+        NumArgs: ::libc::c_uint,
+        Name: *const ::libc::c_char,
+    ) -> LLVMValueRef;
+}
+
+/// Wrapper for a LLVM IR Builder.
+pub struct IRBuilder<'llvm> {
+    builder: LLVMBuilderRef,
+    _ctx: PhantomData<&'llvm ()>,
+}
+
+impl<'llvm> IRBuilder<'llvm> {
+    /// Create a new LLVM IR Builder with the `module`s context.
+    ///
+    /// # Panics
+    ///
+    /// Panics if creating the IR Builder fails.
+    pub fn with_ctx(module: &'llvm Module) -> IRBuilder<'llvm> {
+        let builder = unsafe { LLVMCreateBuilderInContext(module.ctx()) };
+        assert!(!builder.is_null());
+
+        IRBuilder {
+            builder,
+            _ctx: PhantomData,
+        }
+    }
+
+    /// Position the IR Builder at the end of the given Basic Block.
+    pub fn pos_at_end(&self, bb: BasicBlock<'llvm>) {
+        unsafe {
+            LLVMPositionBuilderAtEnd(self.builder, bb.0);
+        }
+    }
+
+    /// Emit a [fadd](https://llvm.org/docs/LangRef.html#fadd-instruction) instruction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn fadd(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
+        debug_assert!(lhs.is_f64(), "fadd: Expected f64 as lhs operand!");
+        debug_assert!(rhs.is_f64(), "fadd: Expected f64 as rhs operand!");
+
+        let value_ref = unsafe {
+            LLVMBuildFAdd(
+                self.builder,
+                lhs.value_ref(),
+                rhs.value_ref(),
+                b"fadd\0".as_ptr().cast(),
+            )
+        };
+        Value::new(value_ref)
+    }
+
+    /// Emit a [fsub](https://llvm.org/docs/LangRef.html#fsub-instruction) instruction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn fsub(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
+        debug_assert!(lhs.is_f64(), "fsub: Expected f64 as lhs operand!");
+        debug_assert!(rhs.is_f64(), "fsub: Expected f64 as rhs operand!");
+
+        let value_ref = unsafe {
+            LLVMBuildFSub(
+                self.builder,
+                lhs.value_ref(),
+                rhs.value_ref(),
+                b"fsub\0".as_ptr().cast(),
+            )
+        };
+        Value::new(value_ref)
+    }
+
+    /// Emit a [fmul](https://llvm.org/docs/LangRef.html#fmul-instruction) instruction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn fmul(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
+        debug_assert!(lhs.is_f64(), "fmul: Expected f64 as lhs operand!");
+        debug_assert!(rhs.is_f64(), "fmul: Expected f64 as rhs operand!");
+
+        let value_ref = unsafe {
+            LLVMBuildFMul(
+                self.builder,
+                lhs.value_ref(),
+                rhs.value_ref(),
+                b"fmul\0".as_ptr().cast(),
+            )
+        };
+        Value::new(value_ref)
+    }
+
+    /// Emit a [fcmult](https://llvm.org/docs/LangRef.html#fcmp-instruction) instruction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn fcmpult(&self, lhs: Value<'llvm>, rhs: Value<'llvm>) -> Value<'llvm> {
+        debug_assert!(lhs.is_f64(), "fcmplt: Expected f64 as lhs operand!");
+        debug_assert!(rhs.is_f64(), "fcmplt: Expected f64 as rhs operand!");
+
+        let value_ref = unsafe {
+            LLVMBuildFCmp(
+                self.builder,
+                LLVMRealPredicate::LLVMRealULT,
+                lhs.value_ref(),
+                rhs.value_ref(),
+                b"fcmplt\0".as_ptr().cast(),
+            )
+        };
+        Value::new(value_ref)
+    }
+
+    /// Emit a [uitofp](https://llvm.org/docs/LangRef.html#uitofp-to-instruction) instruction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn uitofp(&self, val: Value<'llvm>, dest_type: Type<'llvm>) -> Value<'llvm> {
+        debug_assert!(val.is_int(), "uitofp: Expected integer operand!");
+
+        let value_ref = unsafe {
+            LLVMBuildUIToFP(
+                self.builder,
+                val.value_ref(),
+                dest_type.type_ref(),
+                b"uitofp\0".as_ptr().cast(),
+            )
+        };
+        Value::new(value_ref)
+    }
+
+    /// Emit a [call](https://llvm.org/docs/LangRef.html#call-instruction) instruction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn call(&self, fn_value: FnValue<'llvm>, args: &mut [Value<'llvm>]) -> Value<'llvm> {
+        let value_ref = unsafe {
+            LLVMBuildCall2(
+                self.builder,
+                fn_value.ret_type(),
+                fn_value,
+                args.as_mut_ptr(),
+                args.len() as libc::c_uint,
+                b"call\0".as_ptr().cast(),
+            )
+        };
+        Value::new(value_ref)
+    }
+
+    /// Emit a [ret](https://llvm.org/docs/LangRef.html#ret-instruction) instruction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn ret(&self, ret: Value<'llvm>) {
+        let ret = unsafe { LLVMBuildRet(self.builder, ret.value_ref()) };
+        assert!(!ret.is_null());
+    }
+}
+
+impl Drop for IRBuilder<'_> {
+    fn drop(&mut self) {
+        unsafe { LLVMDisposeBuilder(self.builder) }
+    }
+}
diff --git a/src/llvm/mod.rs b/src/llvm/mod.rs
new file mode 100644
index 0000000..f3e54a8
--- /dev/null
+++ b/src/llvm/mod.rs
@@ -0,0 +1,29 @@
+//! Safe wrapper around the LLVM C API.
+//!
+//! References returned from the LLVM API are tied to the `'llvm` lifetime which is bound to the
+//! context where the objects are created in.
+//! We do not offer wrappers to remove or delete any objects in the context and therefore all the
+//! references will be valid for the liftime of the context.
+//!
+//! For the scope of this tutorial we mainly use assertions to validate the results from the LLVM
+//! API calls.
+
+use llvm_sys::prelude::LLVMBasicBlockRef;
+
+use std::marker::PhantomData;
+
+mod builder;
+mod module;
+mod pass_manager;
+mod type_;
+mod value;
+
+pub use builder::IRBuilder;
+pub use module::Module;
+pub use pass_manager::FunctionPassManager;
+pub use type_::Type;
+pub use value::{FnValue, Value};
+
+/// Wrapper for a LLVM Basic Block.
+#[derive(Copy, Clone)]
+pub struct BasicBlock<'llvm>(LLVMBasicBlockRef, PhantomData<&'llvm ()>);
diff --git a/src/llvm/module.rs b/src/llvm/module.rs
new file mode 100644
index 0000000..e0aad96
--- /dev/null
+++ b/src/llvm/module.rs
@@ -0,0 +1,157 @@
+use llvm_sys::{
+    core::{
+        LLVMAddFunction, LLVMAppendBasicBlockInContext, LLVMContextCreate, LLVMContextDispose,
+        LLVMDisposeModule, LLVMDoubleTypeInContext, LLVMDumpModule, LLVMGetNamedFunction,
+        LLVMModuleCreateWithNameInContext,
+    },
+    prelude::{LLVMBool, LLVMContextRef, LLVMModuleRef, LLVMTypeRef},
+    LLVMTypeKind,
+};
+
+use std::convert::TryFrom;
+use std::marker::PhantomData;
+
+use super::{BasicBlock, FnValue, Type};
+use crate::SmallCStr;
+
+// Definition of LLVM C API functions using our `repr(transparent)` types.
+extern "C" {
+    fn LLVMFunctionType(
+        ReturnType: Type<'_>,
+        ParamTypes: *mut Type<'_>,
+        ParamCount: ::libc::c_uint,
+        IsVarArg: LLVMBool,
+    ) -> LLVMTypeRef;
+}
+
+/// Wrapper for a LLVM Module with its own LLVM Context.
+pub struct Module {
+    ctx: LLVMContextRef,
+    module: LLVMModuleRef,
+}
+
+impl<'llvm> Module {
+    /// Create a new Module instance.
+    ///
+    /// # Panics
+    ///
+    /// Panics if creating the context or the module fails.
+    pub fn new() -> Self {
+        let (ctx, module) = unsafe {
+            let c = LLVMContextCreate();
+            let m = LLVMModuleCreateWithNameInContext(b"module\0".as_ptr().cast(), c);
+            assert!(!c.is_null() && !m.is_null());
+            (c, m)
+        };
+
+        Module { ctx, module }
+    }
+
+    /// Get the raw LLVM context reference.
+    #[inline]
+    pub(super) fn ctx(&self) -> LLVMContextRef {
+        self.ctx
+    }
+
+    /// Get the raw LLVM module reference.
+    #[inline]
+    pub(super) fn module(&self) -> LLVMModuleRef {
+        self.module
+    }
+
+    /// Dump LLVM IR emitted into the Module to stdout.
+    pub fn dump(&self) {
+        unsafe { LLVMDumpModule(self.module) };
+    }
+
+    /// Get a type reference representing a `f64` float.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn type_f64(&self) -> Type<'llvm> {
+        let type_ref = unsafe { LLVMDoubleTypeInContext(self.ctx) };
+        Type::new(type_ref)
+    }
+
+    /// Get a type reference representing a `fn(args) -> ret` function.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn type_fn(&'llvm self, args: &mut [Type<'llvm>], ret: Type<'llvm>) -> Type<'llvm> {
+        let type_ref = unsafe {
+            LLVMFunctionType(
+                ret,
+                args.as_mut_ptr(),
+                args.len() as libc::c_uint,
+                0, /* IsVarArg */
+            )
+        };
+        Type::new(type_ref)
+    }
+
+    /// Add a function with the given `name` and `fn_type` to the module and return a value
+    /// reference representing the function.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer or `name` could not be converted to a
+    /// [`SmallCStr`].
+    pub fn add_fn(&'llvm self, name: &str, fn_type: Type<'llvm>) -> FnValue<'llvm> {
+        debug_assert_eq!(
+            fn_type.kind(),
+            LLVMTypeKind::LLVMFunctionTypeKind,
+            "Expected a function type when adding a function!"
+        );
+
+        let name = SmallCStr::try_from(name)
+            .expect("Failed to convert 'name' argument to small C string!");
+
+        let value_ref = unsafe { LLVMAddFunction(self.module, name.as_ptr(), fn_type.type_ref()) };
+        FnValue::new(value_ref)
+    }
+
+    /// Get a function value reference to the function with the given `name` if it was previously
+    /// added to the module with [`add_fn`][Module::add_fn].
+    ///
+    /// # Panics
+    ///
+    /// Panics if `name` could not be converted to a [`SmallCStr`].
+    pub fn get_fn(&'llvm self, name: &str) -> Option<FnValue<'llvm>> {
+        let name = SmallCStr::try_from(name)
+            .expect("Failed to convert 'name' argument to small C string!");
+
+        let value_ref = unsafe { LLVMGetNamedFunction(self.module, name.as_ptr()) };
+
+        (!value_ref.is_null()).then(|| FnValue::new(value_ref))
+    }
+
+    /// Append a Basic Block to the end of the function referenced by the value reference
+    /// `fn_value`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn append_basic_block(&'llvm self, fn_value: FnValue<'llvm>) -> BasicBlock<'llvm> {
+        let block = unsafe {
+            LLVMAppendBasicBlockInContext(
+                self.ctx,
+                fn_value.value_ref(),
+                b"block\0".as_ptr().cast(),
+            )
+        };
+        assert!(!block.is_null());
+
+        BasicBlock(block, PhantomData)
+    }
+}
+
+impl Drop for Module {
+    fn drop(&mut self) {
+        unsafe {
+            LLVMDisposeModule(self.module);
+            LLVMContextDispose(self.ctx);
+        }
+    }
+}
diff --git a/src/llvm/pass_manager.rs b/src/llvm/pass_manager.rs
new file mode 100644
index 0000000..1551875
--- /dev/null
+++ b/src/llvm/pass_manager.rs
@@ -0,0 +1,75 @@
+use llvm_sys::{
+    core::{
+        LLVMCreateFunctionPassManagerForModule, LLVMDisposePassManager,
+        LLVMInitializeFunctionPassManager, LLVMRunFunctionPassManager,
+    },
+    prelude::LLVMPassManagerRef,
+    transforms::{
+        instcombine::LLVMAddInstructionCombiningPass,
+        scalar::{LLVMAddCFGSimplificationPass, LLVMAddNewGVNPass, LLVMAddReassociatePass},
+    },
+};
+
+use std::marker::PhantomData;
+
+use super::{FnValue, Module};
+
+/// Wrapper for a LLVM Function PassManager (legacy).
+pub struct FunctionPassManager<'llvm> {
+    fpm: LLVMPassManagerRef,
+    _ctx: PhantomData<&'llvm ()>,
+}
+
+impl<'llvm> FunctionPassManager<'llvm> {
+    /// Create a new Function PassManager with the following optimization passes
+    /// - InstructionCombiningPass
+    /// - ReassociatePass
+    /// - NewGVNPass
+    /// - CFGSimplificationPass
+    ///
+    /// The list of selected optimization passes is taken from the tutorial chapter [LLVM
+    /// Optimization Passes](https://llvm.org/docs/tutorial/MyFirstLanguageFrontend/LangImpl04.html#id3).
+    pub fn with_ctx(module: &'llvm Module) -> FunctionPassManager<'llvm> {
+        let fpm = unsafe {
+            // Borrows module reference.
+            LLVMCreateFunctionPassManagerForModule(module.module())
+        };
+        assert!(!fpm.is_null());
+
+        unsafe {
+            // Do simple "peephole" optimizations and bit-twiddling optzns.
+            LLVMAddInstructionCombiningPass(fpm);
+            // Reassociate expressions.
+            LLVMAddReassociatePass(fpm);
+            // Eliminate Common SubExpressions.
+            LLVMAddNewGVNPass(fpm);
+            // Simplify the control flow graph (deleting unreachable blocks, etc).
+            LLVMAddCFGSimplificationPass(fpm);
+
+            let fail = LLVMInitializeFunctionPassManager(fpm);
+            assert_eq!(fail, 0);
+        }
+
+        FunctionPassManager {
+            fpm,
+            _ctx: PhantomData,
+        }
+    }
+
+    /// Run the optimization passes registered with the Function PassManager on the function
+    /// referenced by `fn_value`.
+    pub fn run(&'llvm self, fn_value: FnValue<'llvm>) {
+        unsafe {
+            // Returns 1 if any of the passes modified the function, false otherwise.
+            LLVMRunFunctionPassManager(self.fpm, fn_value.value_ref());
+        }
+    }
+}
+
+impl Drop for FunctionPassManager<'_> {
+    fn drop(&mut self) {
+        unsafe {
+            LLVMDisposePassManager(self.fpm);
+        }
+    }
+}
diff --git a/src/llvm/type_.rs b/src/llvm/type_.rs
new file mode 100644
index 0000000..8668c7c
--- /dev/null
+++ b/src/llvm/type_.rs
@@ -0,0 +1,58 @@
+use llvm_sys::{
+    core::{LLVMConstReal, LLVMDumpType, LLVMGetTypeKind},
+    prelude::LLVMTypeRef,
+    LLVMTypeKind,
+};
+
+use std::marker::PhantomData;
+
+use super::Value;
+
+/// Wrapper for a LLVM Type Reference.
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct Type<'llvm>(LLVMTypeRef, PhantomData<&'llvm ()>);
+
+impl<'llvm> Type<'llvm> {
+    /// Create a new Type instance.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `type_ref` is a null pointer.
+    pub(super) fn new(type_ref: LLVMTypeRef) -> Self {
+        assert!(!type_ref.is_null());
+        Type(type_ref, PhantomData)
+    }
+
+    /// Get the raw LLVM type reference.
+    #[inline]
+    pub(super) fn type_ref(&self) -> LLVMTypeRef {
+        self.0
+    }
+
+    /// Get the LLVM type kind for the given type reference.
+    pub(super) fn kind(&self) -> LLVMTypeKind {
+        unsafe { LLVMGetTypeKind(self.type_ref()) }
+    }
+
+    /// Dump the LLVM Type to stdout.
+    pub fn dump(&self) {
+        unsafe { LLVMDumpType(self.type_ref()) };
+    }
+
+    /// Get a value reference representing the const `f64` value.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn const_f64(self, n: f64) -> Value<'llvm> {
+        debug_assert_eq!(
+            self.kind(),
+            LLVMTypeKind::LLVMDoubleTypeKind,
+            "Expected a double type when creating const f64 value!"
+        );
+
+        let value_ref = unsafe { LLVMConstReal(self.type_ref(), n) };
+        Value::new(value_ref)
+    }
+}
diff --git a/src/llvm/value.rs b/src/llvm/value.rs
new file mode 100644
index 0000000..9b79c69
--- /dev/null
+++ b/src/llvm/value.rs
@@ -0,0 +1,168 @@
+use llvm_sys::{
+    analysis::{LLVMVerifierFailureAction, LLVMVerifyFunction},
+    core::{
+        LLVMCountBasicBlocks, LLVMCountParams, LLVMDumpValue, LLVMGetParam, LLVMGetReturnType,
+        LLVMGetValueKind, LLVMGetValueName2, LLVMSetValueName2, LLVMTypeOf,
+    },
+    prelude::LLVMValueRef,
+    LLVMTypeKind, LLVMValueKind,
+};
+
+use std::ffi::CStr;
+use std::marker::PhantomData;
+use std::ops::Deref;
+
+use super::Type;
+
+/// Wrapper for a LLVM Value Reference.
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct Value<'llvm>(LLVMValueRef, PhantomData<&'llvm ()>);
+
+impl<'llvm> Value<'llvm> {
+    /// Create a new Value instance.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `value_ref` is a null pointer.
+    pub(super) fn new(value_ref: LLVMValueRef) -> Self {
+        assert!(!value_ref.is_null());
+        Value(value_ref, PhantomData)
+    }
+
+    /// Get the raw LLVM value reference.
+    #[inline]
+    pub(super) fn value_ref(&self) -> LLVMValueRef {
+        self.0
+    }
+
+    /// Get the LLVM value kind for the given value reference.
+    pub(super) fn kind(&self) -> LLVMValueKind {
+        unsafe { LLVMGetValueKind(self.value_ref()) }
+    }
+
+    /// Dump the LLVM Value to stdout.
+    pub fn dump(&self) {
+        unsafe { LLVMDumpValue(self.value_ref()) };
+    }
+
+    /// Get a type reference representing for the given value reference.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn type_of(&self) -> Type<'llvm> {
+        let type_ref = unsafe { LLVMTypeOf(self.value_ref()) };
+        Type::new(type_ref)
+    }
+
+    /// Set the name for the given value reference.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn set_name(&self, name: &str) {
+        unsafe { LLVMSetValueName2(self.value_ref(), name.as_ptr().cast(), name.len()) };
+    }
+
+    /// Get the name for the given value reference.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn get_name(&self) -> &'llvm str {
+        let name = unsafe {
+            let mut len: libc::size_t = 0;
+            let name = LLVMGetValueName2(self.0, &mut len as _);
+            assert!(!name.is_null());
+
+            CStr::from_ptr(name)
+        };
+
+        // TODO: Does this string live for the time of the LLVM context?!
+        name.to_str()
+            .expect("Expected valid UTF8 string from LLVM API")
+    }
+
+    /// Check if value is of `f64` type.
+    pub fn is_f64(&self) -> bool {
+        self.type_of().kind() == LLVMTypeKind::LLVMDoubleTypeKind
+    }
+
+    /// Check if value is of integer type.
+    pub fn is_int(&self) -> bool {
+        self.type_of().kind() == LLVMTypeKind::LLVMIntegerTypeKind
+    }
+}
+
+/// Wrapper for a LLVM Value Reference specialized for contexts where function values are needed.
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct FnValue<'llvm>(Value<'llvm>);
+
+impl<'llvm> Deref for FnValue<'llvm> {
+    type Target = Value<'llvm>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<'llvm> FnValue<'llvm> {
+    /// Create a new FnValue instance.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `value_ref` is a null pointer.
+    pub(super) fn new(value_ref: LLVMValueRef) -> Self {
+        let value = Value::new(value_ref);
+        debug_assert_eq!(
+            value.kind(),
+            LLVMValueKind::LLVMFunctionValueKind,
+            "Expected a fn value when constructing FnValue!"
+        );
+
+        FnValue(value)
+    }
+
+    /// Get a type reference representing the return value of the given function value.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer.
+    pub fn ret_type(&self) -> Type<'llvm> {
+        let type_ref = unsafe { LLVMGetReturnType(LLVMTypeOf(self.value_ref())) };
+        Type::new(type_ref)
+    }
+
+    /// Get the number of function arguments for the given function value.
+    pub fn args(&self) -> usize {
+        unsafe { LLVMCountParams(self.value_ref()) as usize }
+    }
+
+    /// Get a value reference for the function argument at index `idx`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if LLVM API returns a `null` pointer or indexed out of bounds.
+    pub fn arg(&self, idx: usize) -> Value<'llvm> {
+        assert!(idx < self.args());
+
+        let value_ref = unsafe { LLVMGetParam(self.value_ref(), idx as libc::c_uint) };
+        Value::new(value_ref)
+    }
+
+    /// Get the number of Basic Blocks for the given function value.
+    pub fn basic_blocks(&self) -> usize {
+        unsafe { LLVMCountBasicBlocks(self.value_ref()) as usize }
+    }
+
+    /// Verify that the given function is valid.
+    pub fn verify(&self) -> bool {
+        unsafe {
+            LLVMVerifyFunction(
+                self.value_ref(),
+                LLVMVerifierFailureAction::LLVMPrintMessageAction,
+            ) == 0
+        }
+    }
+}