--- /dev/null
+(*===----------------------------------------------------------------------===
+ * Code Generation
+ *===----------------------------------------------------------------------===*)
+
+open Llvm
+
+exception Error of string
+
+let context = global_context ()
+let the_module = create_module context "my cool jit"
+let builder = builder context
+let named_values:(string, llvalue) Hashtbl.t = Hashtbl.create 10
+let double_type = double_type context
+
+let rec codegen_expr = function
+ | Ast.Number n -> const_float double_type n
+ | Ast.Variable name ->
+ (try Hashtbl.find named_values name with
+ | Not_found -> raise (Error "unknown variable name"))
+ | Ast.Unary (op, operand) ->
+ let operand = codegen_expr operand in
+ let callee = "unary" ^ (String.make 1 op) in
+ let callee =
+ match lookup_function callee the_module with
+ | Some callee -> callee
+ | None -> raise (Error "unknown unary operator")
+ in
+ build_call callee [|operand|] "unop" builder
+ | Ast.Binary (op, lhs, rhs) ->
+ let lhs_val = codegen_expr lhs in
+ let rhs_val = codegen_expr rhs in
+ begin
+ match op with
+ | '+' -> build_add lhs_val rhs_val "addtmp" builder
+ | '-' -> build_sub lhs_val rhs_val "subtmp" builder
+ | '*' -> build_mul lhs_val rhs_val "multmp" builder
+ | '<' ->
+ (* Convert bool 0/1 to double 0.0 or 1.0 *)
+ let i = build_fcmp Fcmp.Ult lhs_val rhs_val "cmptmp" builder in
+ build_uitofp i double_type "booltmp" builder
+ | _ ->
+ (* If it wasn't a builtin binary operator, it must be a user defined
+ * one. Emit a call to it. *)
+ let callee = "binary" ^ (String.make 1 op) in
+ let callee =
+ match lookup_function callee the_module with
+ | Some callee -> callee
+ | None -> raise (Error "binary operator not found!")
+ in
+ build_call callee [|lhs_val; rhs_val|] "binop" builder
+ end
+ | Ast.Call (callee, args) ->
+ (* Look up the name in the module table. *)
+ let callee =
+ match lookup_function callee the_module with
+ | Some callee -> callee
+ | None -> raise (Error "unknown function referenced")
+ in
+ let params = params callee in
+
+ (* If argument mismatch error. *)
+ if Array.length params == Array.length args then () else
+ raise (Error "incorrect # arguments passed");
+ let args = Array.map codegen_expr args in
+ build_call callee args "calltmp" builder
+ | Ast.If (cond, then_, else_) ->
+ let cond = codegen_expr cond in
+
+ (* Convert condition to a bool by comparing equal to 0.0 *)
+ let zero = const_float double_type 0.0 in
+ let cond_val = build_fcmp Fcmp.One cond zero "ifcond" builder in
+
+ (* Grab the first block so that we might later add the conditional branch
+ * to it at the end of the function. *)
+ let start_bb = insertion_block builder in
+ let the_function = block_parent start_bb in
+
+ let then_bb = append_block context "then" the_function in
+
+ (* Emit 'then' value. *)
+ position_at_end then_bb builder;
+ let then_val = codegen_expr then_ in
+
+ (* Codegen of 'then' can change the current block, update then_bb for the
+ * phi. We create a new name because one is used for the phi node, and the
+ * other is used for the conditional branch. *)
+ let new_then_bb = insertion_block builder in
+
+ (* Emit 'else' value. *)
+ let else_bb = append_block context "else" the_function in
+ position_at_end else_bb builder;
+ let else_val = codegen_expr else_ in
+
+ (* Codegen of 'else' can change the current block, update else_bb for the
+ * phi. *)
+ let new_else_bb = insertion_block builder in
+
+ (* Emit merge block. *)
+ let merge_bb = append_block context "ifcont" the_function in
+ position_at_end merge_bb builder;
+ let incoming = [(then_val, new_then_bb); (else_val, new_else_bb)] in
+ let phi = build_phi incoming "iftmp" builder in
+
+ (* Return to the start block to add the conditional branch. *)
+ position_at_end start_bb builder;
+ ignore (build_cond_br cond_val then_bb else_bb builder);
+
+ (* Set a unconditional branch at the end of the 'then' block and the
+ * 'else' block to the 'merge' block. *)
+ position_at_end new_then_bb builder; ignore (build_br merge_bb builder);
+ position_at_end new_else_bb builder; ignore (build_br merge_bb builder);
+
+ (* Finally, set the builder to the end of the merge block. *)
+ position_at_end merge_bb builder;
+
+ phi
+ | Ast.For (var_name, start, end_, step, body) ->
+ (* Emit the start code first, without 'variable' in scope. *)
+ let start_val = codegen_expr start in
+
+ (* Make the new basic block for the loop header, inserting after current
+ * block. *)
+ let preheader_bb = insertion_block builder in
+ let the_function = block_parent preheader_bb in
+ let loop_bb = append_block context "loop" the_function in
+
+ (* Insert an explicit fall through from the current block to the
+ * loop_bb. *)
+ ignore (build_br loop_bb builder);
+
+ (* Start insertion in loop_bb. *)
+ position_at_end loop_bb builder;
+
+ (* Start the PHI node with an entry for start. *)
+ let variable = build_phi [(start_val, preheader_bb)] var_name builder in
+
+ (* Within the loop, the variable is defined equal to the PHI node. If it
+ * shadows an existing variable, we have to restore it, so save it
+ * now. *)
+ let old_val =
+ try Some (Hashtbl.find named_values var_name) with Not_found -> None
+ in
+ Hashtbl.add named_values var_name variable;
+
+ (* Emit the body of the loop. This, like any other expr, can change the
+ * current BB. Note that we ignore the value computed by the body, but
+ * don't allow an error *)
+ ignore (codegen_expr body);
+
+ (* Emit the step value. *)
+ let step_val =
+ match step with
+ | Some step -> codegen_expr step
+ (* If not specified, use 1.0. *)
+ | None -> const_float double_type 1.0
+ in
+
+ let next_var = build_add variable step_val "nextvar" builder in
+
+ (* Compute the end condition. *)
+ let end_cond = codegen_expr end_ in
+
+ (* Convert condition to a bool by comparing equal to 0.0. *)
+ let zero = const_float double_type 0.0 in
+ let end_cond = build_fcmp Fcmp.One end_cond zero "loopcond" builder in
+
+ (* Create the "after loop" block and insert it. *)
+ let loop_end_bb = insertion_block builder in
+ let after_bb = append_block context "afterloop" the_function in
+
+ (* Insert the conditional branch into the end of loop_end_bb. *)
+ ignore (build_cond_br end_cond loop_bb after_bb builder);
+
+ (* Any new code will be inserted in after_bb. *)
+ position_at_end after_bb builder;
+
+ (* Add a new entry to the PHI node for the backedge. *)
+ add_incoming (next_var, loop_end_bb) variable;
+
+ (* Restore the unshadowed variable. *)
+ begin match old_val with
+ | Some old_val -> Hashtbl.add named_values var_name old_val
+ | None -> ()
+ end;
+
+ (* for expr always returns 0.0. *)
+ const_null double_type
+
+let codegen_proto = function
+ | Ast.Prototype (name, args) | Ast.BinOpPrototype (name, args, _) ->
+ (* Make the function type: double(double,double) etc. *)
+ let doubles = Array.make (Array.length args) double_type in
+ let ft = function_type double_type doubles in
+ let f =
+ match lookup_function name the_module with
+ | None -> declare_function name ft the_module
+
+ (* If 'f' conflicted, there was already something named 'name'. If it
+ * has a body, don't allow redefinition or reextern. *)
+ | Some f ->
+ (* If 'f' already has a body, reject this. *)
+ if block_begin f <> At_end f then
+ raise (Error "redefinition of function");
+
+ (* If 'f' took a different number of arguments, reject. *)
+ if element_type (type_of f) <> ft then
+ raise (Error "redefinition of function with different # args");
+ f
+ in
+
+ (* Set names for all arguments. *)
+ Array.iteri (fun i a ->
+ let n = args.(i) in
+ set_value_name n a;
+ Hashtbl.add named_values n a;
+ ) (params f);
+ f
+
+let codegen_func the_fpm = function
+ | Ast.Function (proto, body) ->
+ Hashtbl.clear named_values;
+ let the_function = codegen_proto proto in
+
+ (* If this is an operator, install it. *)
+ begin match proto with
+ | Ast.BinOpPrototype (name, args, prec) ->
+ let op = name.[String.length name - 1] in
+ Hashtbl.add Parser.binop_precedence op prec;
+ | _ -> ()
+ end;
+
+ (* Create a new basic block to start insertion into. *)
+ let bb = append_block context "entry" the_function in
+ position_at_end bb builder;
+
+ try
+ let ret_val = codegen_expr body in
+
+ (* Finish off the function. *)
+ let _ = build_ret ret_val builder in
+
+ (* Validate the generated code, checking for consistency. *)
+ Llvm_analysis.assert_valid_function the_function;
+
+ (* Optimize the function. *)
+ let _ = PassManager.run_function the_function the_fpm in
+
+ the_function
+ with e ->
+ delete_function the_function;
+ raise e
projects / oota-llvm.git / blobdiff