| (*===----------------------------------------------------------------------=== |
| * 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.Binary (op, lhs, rhs) -> |
| let lhs_val = codegen_expr lhs in |
| let rhs_val = codegen_expr rhs in |
| begin |
| match op with |
| | '+' -> build_fadd lhs_val rhs_val "addtmp" builder |
| | '-' -> build_fsub lhs_val rhs_val "subtmp" builder |
| | '*' -> build_fmul 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 |
| | _ -> raise (Error "invalid binary operator") |
| 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) -> |
| (* 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 |
| |
| (* 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 |
