From 6c3d20bbbbe775b81e247c4a617afe3237596e74 Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Fri, 20 Sep 2019 23:40:21 -0300
Subject: [PATCH] add the basics of llvm codegen

---
 build.zig         |  2 ++
 examples/hello.ry |  8 ++---
 src/codegen.zig   | 85 +++++++++++++++++++++++++++++++++++++++++++++++
 src/llvm.zig      | 26 +++++++++++++++
 src/main.zig      |  4 +++
 5 files changed, 121 insertions(+), 4 deletions(-)
 create mode 100644 src/codegen.zig
 create mode 100644 src/llvm.zig

diff --git a/build.zig b/build.zig
index 2b7df4b..d7502d4 100644
--- a/build.zig
+++ b/build.zig
@@ -6,6 +6,8 @@ pub fn build(b: *Builder) void {
     exe.setBuildMode(mode);
     exe.install();
 
+    exe.linkSystemLibrary("LLVM-8");
+
     const run_cmd = exe.run();
     run_cmd.step.dependOn(b.getInstallStep());
 
diff --git a/examples/hello.ry b/examples/hello.ry
index d7eaae6..5c23845 100644
--- a/examples/hello.ry
+++ b/examples/hello.ry
@@ -5,7 +5,7 @@ fn add(a: i32, b: i32) i32 {
 }
 
 // type is void by default
-fn main() {
-    std.fmt.print("piss\n");
-    std.fmt.print("2 + 2 = %d\n", add(1, 2));
-}
+//fn main() {
+//    print("piss\n");
+//    // print("2 + 2 = %d\n", add(1, 2));
+//}
diff --git a/src/codegen.zig b/src/codegen.zig
new file mode 100644
index 0000000..3e5661c
--- /dev/null
+++ b/src/codegen.zig
@@ -0,0 +1,85 @@
+const std = @import("std");
+const ast = @import("ast.zig");
+const llvm = @import("llvm.zig");
+
+pub const Codegen = struct {
+    allocator: *std.mem.Allocator,
+
+    pub fn init(allocator: *std.mem.Allocator) Codegen {
+        return Codegen{ .allocator = allocator };
+    }
+
+    fn genNode(
+        self: *Codegen,
+        mod: llvm.LLVMModuleRef,
+        node: *const ast.Node,
+    ) !void {
+        switch (node.*) {
+            .Root => @panic("Should not have gotten Root"),
+            .FnDecl => |decl| {
+                const name = decl.func_name.lexeme;
+                const name_cstr = try std.cstr.addNullByte(self.allocator, name);
+                errdefer self.allocator.free(name_cstr);
+
+                //const ret_type = decl.return_type.lexeme;
+
+                var param_types = llvm.LLVMTypeList.init(self.allocator);
+                errdefer param_types.deinit();
+
+                for (decl.params.toSlice()) |param| {
+                    try param_types.append(llvm.LLVMInt32Type());
+                }
+
+                var ret_type = llvm.LLVMFunctionType(
+                    llvm.LLVMInt32Type(),
+                    param_types.toSlice().ptr,
+                    @intCast(c_uint, param_types.len),
+                    0,
+                );
+
+                var func = llvm.LLVMAddFunction(mod, name_cstr.ptr, ret_type);
+                var entry = llvm.LLVMAppendBasicBlock(func, c"entry");
+
+                var builder = llvm.LLVMCreateBuilder();
+                llvm.LLVMPositionBuilderAtEnd(builder, entry);
+
+                // TODO codegen decl.body
+                var tmp = llvm.LLVMBuildAdd(
+                    builder,
+                    llvm.LLVMGetParam(func, 0),
+                    llvm.LLVMGetParam(func, 1),
+                    c"tmp",
+                );
+
+                _ = llvm.LLVMBuildRet(builder, tmp);
+                std.debug.warn("cgen: fn decl done\n");
+            },
+            else => {
+                std.debug.warn("got unhandled Node {}\n", node.*);
+                unreachable;
+            },
+        }
+    }
+
+    pub fn gen(self: *Codegen, root: *ast.Node) !void {
+        std.debug.warn("cgen: start gen\n");
+        var mod = llvm.LLVMModuleCreateWithName(c"awoo");
+        defer llvm.LLVMDisposeModule(mod);
+        std.debug.warn("cgen: got mod\n");
+
+        for (root.Root.toSlice()) |child| {
+            std.debug.warn("cgen: gen child {}\n", child);
+            try self.genNode(mod, &child);
+        }
+
+        std.debug.warn("cgen: done\n");
+
+        var err: ?[*]u8 = null;
+        _ = llvm.LLVMVerifyModule(
+            mod,
+            llvm.LLVMVerifierFailureAction.LLVMAbortProcessAction,
+            &err,
+        );
+        llvm.LLVMDisposeMessage(err);
+    }
+};
diff --git a/src/llvm.zig b/src/llvm.zig
new file mode 100644
index 0000000..8e79786
--- /dev/null
+++ b/src/llvm.zig
@@ -0,0 +1,26 @@
+const std = @import("std");
+
+pub const llvm = @cImport({
+    @cInclude("llvm-c/Core.h");
+    @cInclude("llvm-c/ExecutionEngine.h");
+    @cInclude("llvm-c/Target.h");
+    @cInclude("llvm-c/Analysis.h");
+    @cInclude("llvm-c/BitWriter.h");
+});
+
+usingnamespace llvm;
+
+//pub const LLVMModuleRef = llvm.LLVMModuleRef;
+//pub const LLVMInt32Type = llvm.LLVMInt32Type;
+//pub const LLVMModuleCreateWithName = llvm.LLVMModuleCreateWithName;
+//pub const LLVMFunctionType = llvm.LLVMFunctionType;
+//pub const LLVMAddFunction = llvm.LLVMAddFunction;
+//
+//pub const LLVMBasicBlockRef = llvm.LLVMBasicBlockRef;
+//pub const LLVMAppendBasicBlock = llvm.LLVMAppendBasicBlock;
+//
+//pub const LLVMBuilderRef = llvm.LLVMBuilderRef;
+//pub const LLVMCreateBuilder = llvm.LLVMCreateBuilder;
+//pub const LLVMPositionBuilderAtEnd = llvm.LLVMPositionBuilderAtEnd;
+
+pub const LLVMTypeList = std.ArrayList(llvm.LLVMTypeRef);
diff --git a/src/main.zig b/src/main.zig
index cf09d7c..ea05a3b 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -3,6 +3,7 @@ const std = @import("std");
 const scanners = @import("scanners.zig");
 const parsers = @import("parsers.zig");
 const printer = @import("ast_printer.zig");
+const codegen = @import("codegen.zig");
 
 pub const Result = enum {
     Ok,
@@ -45,6 +46,9 @@ pub fn run(allocator: *std.mem.Allocator, slice: []const u8) !Result {
     std.debug.warn("parse tree\n");
     printer.printNode(root.?, 0);
 
+    var cgen = codegen.Codegen.init(allocator);
+    try cgen.gen(root.?);
+
     return Result.Ok;
 }