add emitting of integer and float literals

- remove panics
 - add emitting for return statements
 - remove default emitting of return a+b;

examples/hello.ry

@@ -1,7 +1,7 @@
 // import std;
 
-fn add(a: i32, b: i32) i32 {
-    return a + b;
+fn add() i32 {
+    return 1 + 1;
 }
 
 // type is void by default

src/codegen.zig

@@ -7,7 +7,10 @@ fn sliceify(non_slice: ?[*]const u8) []const u8 {
     return non_slice.?[0..std.mem.len(u8, non_slice.?)];
 }
 
-pub const CompileError = error{LLVMError};
+pub const CompileError = error{
+    LLVMError,
+    EmitError,
+};
 
 pub const Codegen = struct {
     allocator: *std.mem.Allocator,
@@ -16,7 +19,7 @@ pub const Codegen = struct {
         return Codegen{ .allocator = allocator };
     }
 
-    fn genExpr(self: *Codegen, builder: var, expr: *const ast.Expr) !llvm.LLVMValueRef {
+    fn emitExpr(self: *Codegen, builder: var, expr: *const ast.Expr) anyerror!llvm.LLVMValueRef {
         // TODO if expr is Variable, we should do a variable lookup
         // in a symbol table, going up in scope, etc.
 
@@ -24,32 +27,58 @@ pub const Codegen = struct {
         // TODO Assign modify symbol table
 
         // TODO Calls fetch symbol table, check arity of it at codegen level
-        switch (expr.*) {
+        return switch (expr.*) {
 
             // TODO handle all literals, construct llvm values for them
-            .Literal => |literal| {},
+            .Literal => |literal| blk: {
+                break :blk switch (literal) {
+                    // TODO other literals
+                    .Integer => |val| blk2: {
+                        var val_cstr = try std.cstr.addNullByte(self.allocator, val);
+                        break :blk2 llvm.LLVMConstIntOfString(llvm.LLVMInt32Type(), val_cstr.ptr, 10);
+                    },
+                    .Float => |val| blk2: {
+                        var val_cstr = try std.cstr.addNullByte(self.allocator, val);
+                        break :blk2 llvm.LLVMConstRealOfString(llvm.LLVMDoubleType(), val_cstr.ptr);
+                    },
+                    else => unreachable,
+                };
+            },
             .Binary => |binary| {
-                var left = try self.genExpr(builder, binary.left);
-                var right = try self.genExpr(builder, binary.right);
+                var left = try self.emitExpr(builder, binary.left);
+                var right = try self.emitExpr(builder, binary.right);
 
                 return switch (binary.op.lexeme[0]) {
                     // TODO other operators
                     '+' => llvm.LLVMBuildAdd(builder, left, right, c"addtmp"),
 
                     // TODO codegen errors
-                    else => @panic("invalid binary operator"),
+                    else => {
+                        std.debug.warn("Unexpected binary operator: '{}'\n", binary.op.lexeme);
+                        return CompileError.EmitError;
+                    },
                 };
             },
 
             // TODO codegen errors
-            else => @panic("invalid expr"),
-        }
+            else => {
+                std.debug.warn("Got unexpected expr {}\n", expr.*);
+                return CompileError.EmitError;
+            },
+        };
     }
 
-    fn genFuncStmt(self: *Codegen, builder: var, stmt: *const ast.Stmt) !void {
+    fn emitStmt(self: *Codegen, builder: var, stmt: *const ast.Stmt) !void {
         switch (stmt.*) {
-            .Expr => |expr| try self.genExpr(builder, expr),
-            else => unreachable,
+            .Expr => |expr| _ = try self.emitExpr(builder, expr),
+            .Return => |ret| {
+                var ret_expr = try self.emitExpr(builder, ret.value);
+                _ = llvm.LLVMBuildRet(builder, ret_expr);
+            },
+            else => {
+                std.debug.warn("Got unexpected statement {}\n", stmt.*);
+                return CompileError.EmitError;
+            },
         }
     }
 
@@ -89,18 +118,17 @@ pub const Codegen = struct {
 
                 for (decl.body.toSlice()) |stmt| {
                     // TODO custom function context for us
-                    try self.genFuncStmt(builder, stmt);
+                    try self.emitStmt(builder, &stmt);
                 }
 
-                // TODO codegen decl.body
-                var tmp = llvm.LLVMBuildAdd(
-                    builder,
-                    llvm.LLVMGetParam(func, 0),
-                    llvm.LLVMGetParam(func, 1),
-                    c"tmp",
-                );
+                //var tmp = llvm.LLVMBuildAdd(
+                //    builder,
+                //    llvm.LLVMGetParam(func, 0),
+                //    llvm.LLVMGetParam(func, 1),
+                //    c"tmp",
+                //);
 
-                _ = llvm.LLVMBuildRet(builder, tmp);
+                //_ = llvm.LLVMBuildRet(builder, tmp);
                 std.debug.warn("cgen: fn decl done\n");
             },
             else => {
@@ -156,11 +184,9 @@ pub const Codegen = struct {
         var data_layout = llvm.LLVMCopyStringRepOfTargetData(target_data);
         llvm.LLVMSetDataLayout(mod, data_layout);
 
-        var outpath = try std.mem.dupe(self.allocator, u8, "output.o");
-        var outpath_cstr = try std.cstr.addNullByte(self.allocator, outpath);
+        var outpath_cstr = try std.cstr.addNullByte(self.allocator, "outpath.o");
 
-        //var asmpath = try std.mem.dupe(self.allocator, u8, "output.S");
-        //var asmpath_cstr = try std.cstr.addNullByte(self.allocator, asmpath);
+        //var asmpath_cstr = try std.cstr.addNullByte(self.allocator, "output.S");
 
         var desc = llvm.LLVMGetTargetDescription(target);
         var features = llvm.LLVMGetTargetMachineFeatureString(machine);