From cd62c3f8ccce0d834c333edafe2a825126c2bef6 Mon Sep 17 00:00:00 2001
From: Johannes Stoelp <johannes.stoelp@gmail.com>
Date: Sat, 18 Sep 2021 00:18:28 +0200
Subject: llvm: split into sub-modules

---
 src/llvm/module.rs | 157 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 157 insertions(+)
 create mode 100644 src/llvm/module.rs

(limited to 'src/llvm/module.rs')

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);
+        }
+    }
+}
-- 
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