self-hosted: adding a fn to an llvm module

src-self-hosted/codegen.zig

@@ -0,0 +1,61 @@
+const std = @import("std");
+// TODO codegen pretends that Module is renamed to Build because I plan to
+// do that refactor at some point
+const Build = @import("module.zig").Module;
+// we go through llvm instead of c for 2 reasons:
+// 1. to avoid accidentally calling the non-thread-safe functions
+// 2. patch up some of the types to remove nullability
+const llvm = @import("llvm.zig");
+const ir = @import("ir.zig");
+const Value = @import("value.zig").Value;
+const Type = @import("type.zig").Type;
+const event = std.event;
+
+pub async fn renderToLlvm(build: *Build, fn_val: *Value.Fn, code: *ir.Code) !void {
+    fn_val.base.ref();
+    defer fn_val.base.deref(build);
+    defer code.destroy(build.a());
+
+    const llvm_handle = try build.event_loop_local.getAnyLlvmContext();
+    defer llvm_handle.release(build.event_loop_local);
+
+    const context = llvm_handle.node.data;
+
+    const module = llvm.ModuleCreateWithNameInContext(build.name.ptr(), context) orelse return error.OutOfMemory;
+    defer llvm.DisposeModule(module);
+
+    const builder = llvm.CreateBuilderInContext(context) orelse return error.OutOfMemory;
+    defer llvm.DisposeBuilder(builder);
+
+    var cunit = CompilationUnit{
+        .build = build,
+        .module = module,
+        .builder = builder,
+        .context = context,
+        .lock = event.Lock.init(build.loop),
+    };
+
+    try renderToLlvmModule(&cunit, fn_val, code);
+
+    if (build.verbose_llvm_ir) {
+        llvm.DumpModule(cunit.module);
+    }
+}
+
+pub const CompilationUnit = struct {
+    build: *Build,
+    module: llvm.ModuleRef,
+    builder: llvm.BuilderRef,
+    context: llvm.ContextRef,
+    lock: event.Lock,
+
+    fn a(self: *CompilationUnit) *std.mem.Allocator {
+        return self.build.a();
+    }
+};
+
+pub fn renderToLlvmModule(cunit: *CompilationUnit, fn_val: *Value.Fn, code: *ir.Code) !void {
+    // TODO audit more of codegen.cpp:fn_llvm_value and port more logic
+    const llvm_fn_type = try fn_val.base.typeof.getLlvmType(cunit);
+    const llvm_fn = llvm.AddFunction(cunit.module, fn_val.symbol_name.ptr(), llvm_fn_type);
+}