Add return statements

boot/stage1.s

@@ -1,7 +1,7 @@
 .global _start # Program entry point.
 # s1 - Contains the current position in the source text.
 
-.equ SOURCE_BUFFER_SIZE, 40960
+.equ SOURCE_BUFFER_SIZE, 81920
 
 .section .rodata
 section_rodata: .ascii ".section .rodata\n"
@@ -16,6 +16,7 @@ prologue: .ascii "addi sp, sp, -96\nsw ra, 92(sp)\nsw s0, 88(sp)\naddi s0, sp, 9
 .equ PROLOGUE_SIZE, . - prologue
 epilogue: .ascii "lw ra, 92(sp)\nlw s0, 88(sp)\naddi sp, sp, 96\nret\n"
 .equ EPILOGUE_SIZE, . - epilogue
+
 asm_exit: .ascii "li a0, 0\nli a7, 93\necall\n"
 .equ ASM_EXIT_SIZE, . - asm_exit
 asm_start: .ascii ".type _start, @function\n_start:\n"
@@ -24,6 +25,14 @@ asm_and_a0_a1: .ascii "and a0, a0, a1\n"
 .equ ASM_AND_A0_A1_SIZE, . - asm_and_a0_a1
 asm_or_a0_a1: .ascii "or a0, a0, a1\n"
 .equ ASM_OR_A0_A1_SIZE, . - asm_or_a0_a1
+asm_add_a0_a1: .ascii "add a0, a0, a1\n"
+.equ ASM_ADD_A0_A1_SIZE, . - asm_add_a0_a1
+asm_sub_a0_a1: .ascii "sub a0, a0, a1\n"
+.equ ASM_SUB_A0_A1_SIZE, . - asm_sub_a0_a1
+asm_seqz_a0: .ascii "seqz a0, a0\n"
+.equ ASM_SEQZ_A0_SIZE, . - asm_seqz_a0
+asm_type: .ascii ".type "
+.equ ASM_TYPE_SIZE, . - asm_type
 
 .section .bss
 .type source_code, @object
@@ -67,7 +76,7 @@ _build_binary_expression:
 	call _read_token
 	sw a0, 20(sp)
 
-	li t0, 0x26 # &
+	li t0, '&'
 	sw t0, 16(sp)
 	mv a0, s1
 	lw a1, 20(sp)
@@ -83,7 +92,7 @@ _build_binary_expression:
 	call _token_compare
 	beqz a0, .L_build_binary_expression_or
 
-	li t0, 0x3d # =
+	li t0, '='
 	sw t0, 16(sp)
 	mv a0, s1
 	lw a1, 20(sp)
@@ -91,32 +100,34 @@ _build_binary_expression:
 	call _token_compare
 	beqz a0, .L_build_binary_expression_equal
 
+	li t0, '+'
+	sw t0, 16(sp)
+	mv a0, s1
+	lw a1, 20(sp)
+	addi a2, sp, 16
+	call _token_compare
+	beqz a0, .L_build_binary_expression_plus
+
+	li t0, '-'
+	sw t0, 16(sp)
+	mv a0, s1
+	lw a1, 20(sp)
+	addi a2, sp, 16
+	call _token_compare
+	beqz a0, .L_build_binary_expression_minus
+
 	j .Lbuild_binary_expression_end
 
 .L_build_binary_expression_equal:
 	addi s1, s1, 1 # Skip =.
 	li a0, 1
 	call _build_expression
-	li t0, 0x0a3161 # a1\n
+	la a0, asm_sub_a0_a1
-	sw t0, 16(sp)
+	li a1, ASM_SUB_A0_A1_SIZE
-	li t0, 0x202c3061 # a0,_
-	sw t0, 12(sp)
-	li t0, 0x202c3061 # a0,_
-	sw t0, 8(sp)
-	li t0, 0x20627573 # sub_
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 15
 	call _write_out
 
-	li t0, 0x0a306120 # _a0\n
+	la a0, asm_seqz_a0
-	sw t0, 16(sp)
+	li a1, ASM_SEQZ_A0_SIZE
-	li t0, 0x2c306120 # _a0,
-	sw t0, 12(sp)
-	li t0, 0x7a716573 # seqz
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 12
 	call _write_out
 
 	j .Lbuild_binary_expression_end
@@ -141,6 +152,26 @@ _build_binary_expression:
 
 	j .Lbuild_binary_expression_end
 
+.L_build_binary_expression_plus:
+	addi s1, s1, 1 # Skip +.
+	li a0, 1
+	call _build_expression
+	la a0, asm_add_a0_a1
+	li a1, ASM_ADD_A0_A1_SIZE
+	call _write_out
+
+	j .Lbuild_binary_expression_end
+
+.L_build_binary_expression_minus:
+	addi s1, s1, 1 # Skip -.
+	li a0, 1
+	call _build_expression
+	la a0, asm_sub_a0_a1
+	li a1, ASM_SUB_A0_A1_SIZE
+	call _write_out
+
+	j .Lbuild_binary_expression_end
+
 .Lbuild_binary_expression_end:
 	# Epilogue.
 	lw ra, 28(sp)
@@ -237,11 +268,8 @@ _build_expression:
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
+	li a0, '\n'
-	sw t0, 16(sp)
+	call _put_char
-	addi a0, sp, 16
-	li a1, 1
-	call _write_out
 
 	j .Lbuild_expression_advance
 
@@ -262,7 +290,7 @@ _build_expression:
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 16(sp)
 	li t0, 0x29707328 # (sp)
 	sw t0, 12(sp)
@@ -380,7 +408,7 @@ _compile_identifier:
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 12(sp)
 	li t0, 0x29707328 # (sp)
 	sw t0, 8(sp)
@@ -416,7 +444,6 @@ _compile_call:
 
 .Lcompile_call_paren:
 	call _skip_spaces
-	call _read_token
 	lbu t0, (s1)
 	li t1, 0x29 # )
 	beq t0, t1, .Lcompile_call_complete
@@ -458,7 +485,7 @@ _compile_call:
 	li a1, 1
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 8(sp)
 	li t0, 0x29707328 # (sp)
 	sw t0, 4(sp)
@@ -467,7 +494,6 @@ _compile_call:
 	call _write_out
 
 	call _skip_spaces
-	call _read_token
 	lbu t0, (s1)
 	li t1, ','
 	bne t0, t1, .Lcompile_call_paren
@@ -507,7 +533,7 @@ _compile_call:
 	addi t4, t4, '0'
 	addi t0, t0, '0'
 
-	li t5, 0x0a # \n
+	li t5, '\n'
 	sb t5, 11(sp)
 	li t5, 0x29707328 # (sp)
 	sw t5, 7(sp)
@@ -540,7 +566,7 @@ _compile_call:
 	lw a1, 16(sp)
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 1
@@ -601,6 +627,12 @@ _read_token:
 	li t1, '='
 	beq t0, t1, .Ltoken_character_single
 
+	li t1, '+'
+	beq t0, t1, .Ltoken_character_single
+
+	li t1, '-'
+	beq t0, t1, .Ltoken_character_single
+
 	li t1, '@'
 	beq t0, t1, .Ltoken_character_single
 # Expect an identifier or a number.
@@ -693,11 +725,6 @@ _skip_comment:
 	sw s0, 8(sp)
 	addi s0, sp, 16
 
-	/* DEBUG
-	mv a0, s1
-	li a1, 8
-	call _write_error */
-
 	# Check whether this is a comment.
 	li t0, 0x2a28 # (*
 	sw t0, 4(sp)
@@ -924,12 +951,8 @@ _compile_variable:
 	add s1, s1, a0 # Skip the type.
 
 	# .type identifier, @object
-	li t0, 0x2065 # e_
+	la a0, asm_type
-	sw t0, 12(sp)
+	li a1, ASM_TYPE_SIZE
-	li t0, 0x7079742e # .typ
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 6
 	call _write_out
 
 	lw a0, 28(sp)
@@ -959,7 +982,7 @@ _compile_variable:
 	lw a1, 24(sp)
 	call _write_out
 
-	li t0, 0x202c # ,
+	li t0, 0x202c # ,_
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 2
@@ -969,11 +992,8 @@ _compile_variable:
 	lw a1, 16(sp)
 	call _write_out
 
-	li t0, 0x0a # \n
+	li a0, '\n'
-	sw t0, 12(sp)
+	call _put_char
-	addi a0, sp, 12
-	li a1, 1
-	call _write_out
 
 	# identifier: .zero size
 	lw a0, 28(sp)
@@ -992,11 +1012,8 @@ _compile_variable:
 	lw a1, 16(sp)
 	call _write_out
 
-	li t0, 0x0a # \n
+	li a0, '\n'
-	sw t0, 12(sp)
+	call _put_char
-	addi a0, sp, 12
-	li a1, 1
-	call _write_out
 
 	# Epilogue.
 	lw ra, 36(sp)
@@ -1019,12 +1036,8 @@ _compile_procedure:
 	add s1, s1, a0
 
 	# .type identifier, @function
-	li t0, 0x2065 # e_
+	la a0, asm_type
-	sw t0, 12(sp)
+	li a1, ASM_TYPE_SIZE
-	li t0, 0x7079742e # .typ
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 6
 	call _write_out
 
 	lw a0, 20(sp)
@@ -1235,11 +1248,8 @@ _compile_goto:
 
 	addi s1, s1, 1 # Skip the new line.
 
-	li t0, 0x0a # \n
+	li a0, '\n'
-	sw t0, 8(sp)
+	call _put_char
-	addi a0, sp, 8
-	li a1, 1
-	call _write_out
 
 	# Epilogue.
 	lw ra, 12(sp)
@@ -1280,7 +1290,7 @@ _compile_label:
 	call _write_out
 
 .Lcompile_label_colon:
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 1
@@ -1296,6 +1306,25 @@ _compile_label:
 	addi sp, sp, 16
 	ret
 
+.type _compile_return, @function
+_compile_return:
+	# Prologue.
+	addi sp, sp, -16
+	sw ra, 12(sp)
+	sw s0, 8(sp)
+	addi s0, sp, 16
+
+	addi s1, s1, 6 # Skip return.
+	call _skip_spaces
+
+	call _build_binary_expression
+
+	# Epilogue.
+	lw ra, 12(sp)
+	lw s0, 8(sp)
+	addi sp, sp, 16
+	ret
+
 # Parameters:
 # a0 - Line length.
 # a1 - Whether the section header was already emitted. If not it should be
@@ -1403,6 +1432,16 @@ _compile_line:
 	call _memcmp
 	beqz a0, .Lcompile_line_goto
 
+	li t0, 0x6e72 # rn
+	sw t0, 12(sp)
+	li t0, 0x75746572 # retu
+	sw t0, 8(sp)
+	mv a0, s1
+	addi a1, sp, 8
+	li a2, 6
+	call _memcmp
+	beqz a0, .Lcompile_line_return
+
 	lbu t0, (s1)
 	li t1, '.'
 	beq t0, t1, .Lcompile_line_label
@@ -1416,6 +1455,14 @@ _compile_line:
 	call _compile_label
 	j .Lcompile_line_section
 
+.Lcompile_line_return:
+	/* DEBUG
+	mv a0, s1
+	li a1, 6
+	call _write_error */
+	call _compile_return
+	j .Lcompile_line_section
+
 .Lcompile_line_goto:
 	call _compile_goto
 	j .Lcompile_line_section

boot/stage2.elna

@@ -20,10 +20,10 @@ program
 import dummy
 
 const
-	SOURCE_BUFFER_SIZE := 40960
+	SOURCE_BUFFER_SIZE := 81920
 
 var
-	source_code: [40960]Byte
+	source_code: [81920]Byte
 
 (* Ignores the import. *)
 proc _compile_import()
@@ -36,9 +36,13 @@ begin
 end
 
 proc _build_binary_expression()
+var loca0, loca4, loca8: Word
 begin
 	_build_expression(0)
 
+	loca4 := 0x2c306120 (* _a0, *)
+	loca8 := 0x0a316120 (* _a1\n *)
+
 	_skip_spaces()
 	call _read_token
 	sw a0, 20(sp)
@@ -67,57 +71,81 @@ begin
 	call _token_compare
 	beqz a0, .L_build_binary_expression_equal
 
+	li t0, 0x2b # +
+	sw t0, 16(sp)
+	mv a0, s1
+	lw a1, 20(sp)
+	addi a2, sp, 16
+	call _token_compare
+	beqz a0, .L_build_binary_expression_plus
+
+	li t0, 0x2d # -
+	sw t0, 16(sp)
+	mv a0, s1
+	lw a1, 20(sp)
+	addi a2, sp, 16
+	call _token_compare
+	beqz a0, .L_build_binary_expression_minus
+
 	goto .Lbuild_binary_expression_end
 
 	.L_build_binary_expression_equal
 	_advance(1) (* Skip =. *)
 	_build_expression(1)
-	loca0 := 0x0a3161 (* a1\n *)
+	_write_out(@loca0, 3)
-	_write_out(@loca0, 4)
+	_write_out(@loca4, 4)
-	loca0 := 0x202c3061 (* a0,_ *)
+	_write_out(@loca4, 4)
-	_write_out(@loca0, 4)
+	_write_out(@loca8, 4)
-	loca0 := 0x202c3061 (* a0,_ *)
-	_write_out(@loca0, 4)
-	loca0 := 0x20627573 (* sub_ *)
-	_write_out(@loca0, 4)
 
 	loca0 := 0x7a716573 (* seqz *)
 	_write_out(@loca0, 4)
-	loca0 := 0x2c306120 (* _a0, *)
+	_write_out(@loca4, 4)
-	_write_out(@loca0, 4)
+	_write_out(@loca4, 4)
-	loca0 := 0x0a306120 (* _a0\n *)
-	_write_out(@loca0, 4)
 
 	goto .Lbuild_binary_expression_end
 
 	.L_build_binary_expression_and
 	_advance(1) (* Skip &. *)
 	_build_expression(1)
-	loca0 := 0x20646e61 (* and_ *)
+	loca0 := 0x646e61 (* and *)
-	_write_out(@loca0, 4)
-	loca0 := 0x202c3061 (* a0,_ *)
-	_write_out(@loca0, 4)
-	loca0 := 0x202c3061 (* a0,_ *)
-	_write_out(@loca0, 4)
-	loca0 := 0x0a3161 (* a1\n *)
 	_write_out(@loca0, 3)
+	_write_out(@loca4, 4)
+	_write_out(@loca4, 4)
+	_write_out(@loca8, 4)
 
 	goto .Lbuild_binary_expression_end
 
 	.L_build_binary_expression_or
 	_advance(2) (* Skip or. *)
 	_build_expression(1)
-	loca0 := 0x6120726f (* or a *)
+	loca0 := 0x726f (* or *)
-	_write_out(@loca0, 4)
-	loca0 := 0x61202c30 (* 0, a *)
-	_write_out(@loca0, 4)
-	loca0 := 0x61202c30 (* 0, a *)
-	_write_out(@loca0, 4)
-	loca0 := 0x0a31 (* 1\n *)
 	_write_out(@loca0, 2)
+	_write_out(@loca4, 4)
+	_write_out(@loca4, 4)
+	_write_out(@loca8, 4)
 
 	goto .Lbuild_binary_expression_end
 
+	.L_build_binary_expression_plus
+	_advance(1) (* Skip +. *)
+	_build_expression(1)
+	loca0 := 0x646461 (* add *)
+	_write_out(@loca0, 3)
+	_write_out(@loca4, 4)
+	_write_out(@loca4, 4)
+	_write_out(@loca8, 4)
+
+	goto .Lbuild_binary_expression_end
+
+	.L_build_binary_expression_minus
+	_advance(1) (* Skip -. *)
+	_build_expression(1)
+	loca0 := 0x627573 (* sub *)
+	_write_out(@loca0, 3)
+	_write_out(@loca4, 4)
+	_write_out(@loca4, 4)
+	_write_out(@loca8, 4)
+
 	.Lbuild_binary_expression_end
 end
 
@@ -173,25 +201,20 @@ begin
 	goto .Lbuild_expression_advance
 
 	.Lbuild_expression_address
-	lw t1, 28(sp)
+	loca8 := 0x69646461 (* addi *)
-	li t0, 0x20 # _
+	_write_out(@loca8, 4)
-	sw t0, 16(sp)
+	loca8 := 0x6120 (* _a *)
-	li t0, 0x2c707320 # _sp,
+	_write_out(@loca8, 2)
-	sw t0, 12(sp)
+	_put_char(loca28)
-	li t0, 0x2c006120 # _a\0,
+	loca8 := 0x7073202c (* , sp *)
-	sw t0, 8(sp)
+	_write_out(@loca8, 4)
-	sb t1, 10(sp)
+	loca8 := 0x202c (* ,_ *)
-	li t0, 0x69646461 # addi
+	_write_out(@loca8, 2)
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 13
-	call _write_out
 
 	_advance(1) (* Skip @. *)
 	_skip_spaces()
-	call _read_token
+	loca24 := _current()
-	sw s1, 24(sp)
+	loca20 := _read_token()
-	sw a0, 20(sp)
 
 	lw a0, 24(sp)
 	lw a1, 20(sp)
@@ -199,11 +222,7 @@ begin
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
+	_put_char(0xa)
-	sw t0, 16(sp)
-	addi a0, sp, 16
-	li a1, 1
-	call _write_out
 
 	goto .Lbuild_expression_advance
 
@@ -270,22 +289,22 @@ Left values should be variables named "loca n", where n is the offset
 of the variable on the stack, like loca8 or loca4.
 *)
 proc _compile_identifier()
+var
+	loca0, loca16, loca8: Word
+	loca20, loca12: ^Byte
 begin
-	call _read_token
-
 	(* Save the pointer to the identifier and its length on the stack. *)
-	sw s1, 20(sp)
+	loca20 := _current()
-	sw a0, 16(sp)
+	loca16 := _read_token()
 
-	add s1, s1, a0
+	_advance(loca16)
 	_skip_spaces()
-	call _read_token
 
 	(* Save the pointer and the length of the token following the identifier. *)
-	sw s1, 12(sp)
+	loca12 := _current()
-	sw a0, 8(sp)
+	loca8 := _read_token()
 
-	add s1, s1, a0 # Skip that token.
+	_advance(loca8) # Skip that token.
 	_skip_spaces()
 
 	li t0, 0x3d3a # :=
@@ -304,22 +323,17 @@ begin
 	goto .Lcompile_identifier_end
 
 	.Lcompile_identifier_call
-	lw a0, 20(sp)
+	_compile_call(loca20, loca16)
-	lw a1, 16(sp)
-	call _compile_call
 
 	goto .Lcompile_identifier_end
 
 	.Lcompile_identifier_assign
 	_build_binary_expression()
 
-	li t0, 0x202c30 # 0,_
+	loca0 := 0x61207773 (* sw a *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x61207773 # sw a
+	loca0 := 0x202c30 (* 0,_ *)
-	sw t0, 8(sp)
+	_write_out(@loca0, 3)
-	addi a0, sp, 8
-	li a1, 7
-	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
@@ -327,13 +341,9 @@ begin
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
+	loca0 := 0x29707328 (* (sp) *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x29707328 # (sp)
+	_put_char(0x0a) (* \n *)
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 5
-	call _write_out
 
 	goto .Lcompile_identifier_end
 
@@ -347,15 +357,14 @@ a1 - Length of the procedure name.
 
 Returns the procedure result in a0.
 *)
-proc _compile_call()
+proc _compile_call(loca84: ^Byte, loca80: Word)
+var
+	loca0, loca12: Word
 begin
-	sw a0, 20(sp)
+	loca12 := 0 (* Argument count for a procedure call. *)
-	sw a1, 16(sp)
-	sw zero, 12(sp) # Argument count for a procedure call.
 
 	.Lcompile_call_paren
 	_skip_spaces()
-	call _read_token
 	lbu t0, (s1)
 	li t1, 0x29 # )
 	beq t0, t1, .Lcompile_call_complete
@@ -363,13 +372,10 @@ begin
 	.Lcompile_call_argument
 	_build_expression(0)
 
-	li t0, 0x202c30 # 0,_
+	loca0 := 0x61207773 (* sw a *)
-	sw t0, 8(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x61207773 # sw a
+	loca0 := 0x202c30 (* 0,_ *)
-	sw t0, 4(sp)
+	_write_out(@loca0, 3)
-	addi a0, sp, 4
-	li a1, 7
-	call _write_out
 
 	lw t0, 12(sp) # Argument count for a procedure call.
 
@@ -407,7 +413,6 @@ begin
 	call _write_out
 
 	_skip_spaces()
-	call _read_token
 	lbu t0, (s1)
 	li t1, ','
 	bne t0, t1, .Lcompile_call_paren
@@ -420,7 +425,7 @@ begin
 	goto .Lcompile_call_argument
 
 	.Lcompile_call_complete
-	sw zero, 12(sp)
+	loca12 := 0
 
 	.Lcompile_call_restore
 	(*
@@ -463,30 +468,16 @@ begin
 	li a1, 10
 	call _write_out
 
-	lw t0, 12(sp) # Increment.
+	loca12 := loca12 + 1
-	addi t0, t0, 1
-	sw t0, 12(sp)
-
 	goto .Lcompile_call_restore
 
 	.Lcompile_call_perform
-	li t0, 0x20
+	loca0 := 0x6c6c6163
-	sw t0, 8(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x6c6c6163
+	_put_char(0x20) (* _ *)
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 5
-	call _write_out
 
-	lw a0, 20(sp)
+	_write_out(loca84, loca80)
-	lw a1, 16(sp)
+	_put_char(0x0a) (* \n *)
-	call _write_out
-
-	li t0, 0x0a # \n
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 1
-	call _write_out
 
 	_skip_spaces()
 	_advance(1) (* Skip the close paren. *)
@@ -497,9 +488,10 @@ Reads a token and returns its length in a0.
 _read_token doesn't change s1, it finds the length of the token s1 is pointing to.
 *)
 proc _read_token()
+var loca4: Word
 begin
 	lbu t0, (s1) # t0 = Current character.
-	sw zero, 4(sp)
+	loca4 := 0
 
 	li t1, '.'
 	beq t0, t1, .Ltoken_character_single
@@ -534,6 +526,12 @@ begin
 	li t1, '='
 	beq t0, t1, .Ltoken_character_single
 
+	li t1, '+'
+	beq t0, t1, .Ltoken_character_single
+
+	li t1, '-'
+	beq t0, t1, .Ltoken_character_single
+
 	li t1, '@'
 	beq t0, t1, .Ltoken_character_single
 	(* Expect an identifier or a number. *)
@@ -545,22 +543,16 @@ begin
 	call _is_alnum
 
 	beqz a0, .Ltoken_character_end
-	lw t6, 4(sp)
+	loca4 := loca4 + 1
-	addi t6, t6, 1
-	sw t6, 4(sp)
 	goto .Ltoken_character_loop_do
 
 	.Ltoken_character_single
-	lw t6, 4(sp)
+	loca4 := loca4 + 1
-	addi t6, t6, 1
-	sw t6, 4(sp)
 	goto .Ltoken_character_end
 
 	.Ltoken_character_colon
 	lbu t0, 1(s1) # t0 = The character after the colon.
-	lw t6, 4(sp)
+	loca4 := loca4 + 1
-	addi t6, t6, 1
-	sw t6, 4(sp)
 
 	li t1, '='
 	beq t0, t1, .Ltoken_character_single
@@ -617,11 +609,6 @@ Parameters:
 *)
 proc _skip_comment(loca84: Word)
 begin
-	(* DEBUG
-	mv a0, s1
-	li a1, 8
-	call _write_error *)
-
 	(* Check whether this is a comment. *)
 	li t0, 0x2a28 # (*
 	sw t0, 4(sp)
@@ -774,13 +761,15 @@ begin
 end
 
 proc _compile_variable()
+var
+	loca28, loca16: ^Byte
+	loca0, loca24, loca20: Word
 begin
-	call _read_token
-
 	(* Save the identifier on the stack since it should emitted multiple times. *)
-	sw s1, 28(sp)
+	loca24 := _read_token()
-	sw a0, 24(sp)
+	loca28 := _current()
-	add s1, s1, a0
+
+	_advance(loca24)
 
 	_skip_spaces()
 	_advance(1) (* Skip the colon in front of the type. *)
@@ -788,99 +777,63 @@ begin
 	_skip_spaces()
 	_advance(1) (* Skip the opening bracket. *)
 
-	call _read_token
-
 	(* Save the array size on the stack since it has to be emitted multiple times. *)
-	sw s1, 20(sp)
+	loca16 := _read_token()
-	sw a0, 16(sp)
+	loca20 := _current()
-	add s1, s1, a0
+	_advance(loca16)
 
 	_skip_spaces()
 	_advance(1) (* Skip the closing bracket. *)
 
 	_skip_spaces()
-	call _read_token
+	loca0 := _read_token()
-	add s1, s1, a0 # Skip the type.
+	_advance(loca0) (* Skip the type. *)
 
 	(* .type identifier, @object *)
-	li t0, 0x2065 # e_
+	loca0 := 0x7079742e (* .typ *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x7079742e # .typ
+	loca0 := 0x2065 (* e_ *)
-	sw t0, 8(sp)
+	_write_out(@loca0, 2)
-	addi a0, sp, 8
-	li a1, 6
-	call _write_out
 
-	lw a0, 28(sp)
+	_write_out(loca28, loca24)
-	lw a1, 24(sp)
-	call _write_out
 
-	li t0, 0x0a74 # t\n
+	loca0 := 0x6f40202c (* , @o *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x63656a62 # bjec
+	loca0 := 0x63656a62 (* bjec *)
-	sw t0, 8(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x6f40202c # , @o
+	loca0 := 0x0a74 (* t\n *)
-	sw t0, 4(sp)
+	_write_out(@loca0, 2)
-	addi a0, sp, 4
-	li a1, 10
-	call _write_out
 
 	(* .size identifier, size *)
-	li t0, 0x2065 # e_
+	loca0 := 0x7a69732e (* .siz *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x7a69732e # .siz
+	loca0 := 0x2065 (* e_ *)
-	sw t0, 8(sp)
+	_write_out(@loca0, 2)
-	addi a0, sp, 8
-	li a1, 6
-	call _write_out
 
-	lw a0, 28(sp)
+	_write_out(loca28, loca24)
-	lw a1, 24(sp)
-	call _write_out
 
-	li t0, 0x202c # ,
+	loca0 := 0x202c (* ,_ *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 2)
-	addi a0, sp, 12
-	li a1, 2
-	call _write_out
 
-	lw a0, 20(sp)
+	_write_out(loca20, loca16)
-	lw a1, 16(sp)
+	_put_char(0x0a) (* \n *)
-	call _write_out
-
-	li t0, 0x0a # \n
-	sw t0, 12(sp)
-	addi a0, sp, 12
-	li a1, 1
-	call _write_out
 
 	(* identifier: .zero size *)
-	lw a0, 28(sp)
+	_write_out(loca28, loca24)
-	lw a1, 24(sp)
-	call _write_out
 
-	li t0, 0x206f7265 # ero_
+	loca0 := 0x7a2e203a (* : .z *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x7a2e203a # : .z
+	loca0 := 0x206f7265 (* ero_ *)
-	sw t0, 8(sp)
+	_write_out(@loca0, 4)
-	addi a0, sp, 8
-	li a1, 8
-	call _write_out
 
-	lw a0, 20(sp)
+	_write_out(loca20, loca16)
-	lw a1, 16(sp)
-	call _write_out
 
-	li t0, 0x0a # \n
+	_put_char(0x0a) (* \n *)
-	sw t0, 12(sp)
-	addi a0, sp, 12
-	li a1, 1
-	call _write_out
 end
 
 proc _compile_procedure()
 var
-	loca0, loca8, loca12, loca16: Word
+	loca0, loca4, loca8, loca12, loca16: Word
 	loca20: ^Char
 begin
 	_advance(5) (* Skip proc_ *)
@@ -971,57 +924,49 @@ begin
 	_write_out(@loca0, 4)
 
 	(* Save passed arguments on the stack. *)
-	li t0, 0x0a29 # )\n
+	loca0 := 0x61207773 (* sw a *)
-	sw t0, 12(sp)
+	_write_out(@loca0, 4)
-	li t0, 0x70732834 # 4(sp
+	loca4 := 0x38202c30 (* 0, 8 *)
-	sw t0, 8(sp)
+	_write_out(@loca4, 4)
-	li t0, 0x38202c30 # 0, 8
+	loca8 := 0x70732834 (* 4(sp *)
-	sw t0, 4(sp)
+	_write_out(@loca8, 4)
-	li t0, 0x61207773 # sw a
+	loca12 := 0x0a29 (* )\n *)
-	sw t0, 0(sp)
+	_write_out(@loca12, 2)
-	addi a0, sp, 0
-	li a1, 14
-	call _write_out
 
-	li t0, '0'
+	_write_out(@loca0, 4)
-	sb t0, 8(sp)
+	loca4 := 0x38202c31 (* 1, 8 *)
-	li t0, 0x38202c31 # 1, 8
+	_write_out(@loca4, 4)
-	sw t0, 4(sp)
+	loca8 := 0x70732830 (* 0(sp *)
-	addi a0, sp, 0
+	_write_out(@loca8, 4)
-	li a1, 14
+	_write_out(@loca12, 2)
-	call _write_out
 
-	li t0, '6'
+	_write_out(@loca0, 4)
-	sb t0, 8(sp)
+	loca4 := 0x37202c32 (* 2, 7 *)
-	li t0, 0x37202c32 # 2, 7
+	_write_out(@loca4, 4)
-	sw t0, 4(sp)
+	loca8 := 0x70732836 (* 6(sp *)
-	addi a0, sp, 0
+	_write_out(@loca8, 4)
-	li a1, 14
+	_write_out(@loca12, 2)
-	call _write_out
 
-	li t0, '2'
+	_write_out(@loca0, 4)
-	sb t0, 8(sp)
+	loca4 := 0x37202c33 (* 3, 7 *)
-	li t0, 0x37202c33 # 3, 7
+	_write_out(@loca4, 4)
-	sw t0, 4(sp)
+	loca8 := 0x70732832 (* 2(sp *)
-	addi a0, sp, 0
+	_write_out(@loca8, 4)
-	li a1, 14
+	_write_out(@loca12, 2)
-	call _write_out
 
-	li t0, '8'
+	_write_out(@loca0, 4)
-	sb t0, 8(sp)
+	loca4 := 0x36202c34 (* 4, 6 *)
-	li t0, 0x36202c34 # 4, 6
+	_write_out(@loca4, 4)
-	sw t0, 4(sp)
+	loca8 := 0x70732838 (* 8(sp *)
-	addi a0, sp, 0
+	_write_out(@loca8, 4)
-	li a1, 14
+	_write_out(@loca12, 2)
-	call _write_out
 
-	li t0, '4'
+	_write_out(@loca0, 4)
-	sb t0, 8(sp)
+	loca4 := 0x36202c35 (* 5, 6 *)
-	li t0, 0x36202c35 # 5, 6
+	_write_out(@loca4, 4)
-	sw t0, 4(sp)
+	loca8 := 0x70732838 (* 4(sp *)
-	addi a0, sp, 0
+	_write_out(@loca8, 4)
-	li a1, 14
+	_write_out(@loca12, 2)
-	call _write_out
 
 	(* Generate the body of the procedure. *)
 	.Lcompile_procedure_body
@@ -1042,7 +987,7 @@ begin
 	goto .Lcompile_procedure_body
 
 	.Lcompile_procedure_end
-	add s1, s1, 4 # Skip end\n.
+	_advance(4) (* Skip end\n. *)
 
 	(* Generate the procedure epilogue with a predefined stack size. *)
 	loca0 := 0x7220776c # lw r
@@ -1124,45 +1069,38 @@ begin
 end
 
 proc _compile_goto()
+var
+	loca0: Word
+	loca8: ^Byte
 begin
 	_advance(4) (* Skip the goto keyword. *)
 
-	li t0, 0x206a # j_
+	loca0 := 0x206a (* j_ *)
-	sw t0, 8(sp)
+	_write_out(@loca0, 2)
-	addi a0, sp, 8
-	li a1, 2
-	call _write_out
 
 	_skip_spaces()
-	sw s1, 8(sp) # We should be on dot the label is beginning with.
+	loca8 := _current() (* We should be on dot the label is beginning with. *)
 	_advance(1)
 
-	call _read_token
+	loca0 := _read_token()
-	add s1, s1, a0
+	_advance(loca0)
-	addi a1, a0, 1 # Label length and the dot.
+	loca0 := loca0 + 1 (* Label length and the dot. *)
-	lw a0, 8(sp) # Saved dot position.
+	_write_out(loca8, loca0)
-	call _write_out
 
 	_advance(1) (* Skip the new line. *)
-
+	_put_char(0x0a) (* \n *)
-	li t0, 0x0a # \n
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 1
-	call _write_out
 end
 
 (* a0 - Line length. *)
-proc _compile_label()
+proc _compile_label(loca84: Word)
+var
+	loca0: Word
 begin
-	sw a0, 0(sp) # Save the line length.
-
 	(* Write the whole line as is. *)
-	mv a0, s1
+	loca0 := _current()
-	lw a1, 0(sp)
+	_write_out(loca0, loca84)
-	call _write_out
 
-	lw t0, 0(sp) # Line length.
+	lw t0, 84(sp) # Line length.
 	mv t1, s1 # Line start.
 
 	add t1, t1, t0
@@ -1172,22 +1110,19 @@ begin
 	li t2, ':'
 	beq t1, t2, .Lcompile_label_colon
 
-	li t0, 0x3a # :
+	_put_char(0x3a) (* : *)
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 1
-	call _write_out
 
 	.Lcompile_label_colon
-	li t0, 0x0a # \n
+	_put_char(0x0a) (* \n *)
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 1
-	call _write_out
 
-	lw a0, 0(sp)
+	_advance(loca84)
-	addi a0, a0, 1 # Skip the new line as well.
+end
-	add s1, s1, a0 # Skip the line.
+
+proc _compile_return()
+begin
+	_advance(6) (* Skip return. *)
+	_skip_spaces()
+	_build_binary_expression()
 end
 
 (*
@@ -1199,12 +1134,8 @@ Parameters:
 Returns 1 in a0 if the parsed line contained a text section element such a
 procedure or the program entry point. Otherwise sets a0 to 0.
 *)
-proc _compile_line()
+proc _compile_line(loca84: Word, loca80: Bool)
 begin
-	(* Preserve passed arguments. *)
-	sw a0, 20(sp)
-	sw a1, 16(sp)
-
 	beqz a0, .Lcompile_line_empty # Skip an empty line.
 
 	lbu t0, (s1)
@@ -1293,6 +1224,16 @@ begin
 	call _memcmp
 	beqz a0, .Lcompile_line_goto
 
+	li t0, 0x6e72 # rn
+	sw t0, 12(sp)
+	li t0, 0x75746572 # retu
+	sw t0, 8(sp)
+	mv a0, s1
+	addi a1, sp, 8
+	li a2, 6
+	call _memcmp
+	beqz a0, .Lcompile_line_return
+
 	lbu t0, (s1)
 	li t1, '.'
 	beq t0, t1, .Lcompile_line_label
@@ -1302,8 +1243,15 @@ begin
 	goto .Lcompile_line_unchanged (* Else. *)
 
 	.Lcompile_line_label
-	lw a0, 20(sp)
+	_compile_label(loca84)
-	call _compile_label
+	goto .Lcompile_line_section
+
+	.Lcompile_line_return
+	(* DEBUG
+	mv a0, s1
+	li a1, 8
+	call _write_error *)
+	_compile_return()
 	goto .Lcompile_line_section
 
 	.Lcompile_line_goto
@@ -1323,7 +1271,7 @@ begin
 	goto .Lcompile_line_section
 
 	.Lcompile_line_begin
-	lw a1, 16(sp)
+	lw a1, 80(sp)
 	bnez a1, .Lcompile_line_compile_entry
 	_compile_text_section()
 	.Lcompile_line_compile_entry
@@ -1336,7 +1284,7 @@ begin
 	goto .Lcompile_line_section
 
 	.Lcompile_line_procedure
-	lw a1, 16(sp)
+	lw a1, 80(sp)
 	bnez a1, .Lcompile_line_compile_procedure
 	_compile_text_section()
 	.Lcompile_line_compile_procedure
@@ -1353,8 +1301,7 @@ begin
 	goto .Lcompile_line_section
 
 	.Lcompile_line_comment
-	lw a0, 20(sp)
+	_skip_comment(loca84)
-	call _skip_comment
 	goto .Lcompile_line_section
 
 	.Lcompile_line_empty
@@ -1362,8 +1309,7 @@ begin
 	goto .Lcompile_line_section
 
 	.Lcompile_line_unchanged
-	lw a0, 20(sp)
+	_compile_assembly(loca84)
-	call _compile_assembly
 	goto .Lcompile_line_section
 
 	.Lcompile_line_section
@@ -1445,31 +1391,35 @@ end
 (* Finds the end of the line and returns its length in a0. *)
 proc _read_line()
 begin
-	mv t0, s1 # Local position in the source text.
+	loca0 := _current() (* Local position in the source text. *)
 
 	.Lread_line_do
+	lw t0, 0(sp)
 	lbu t1, (t0) # t1 = Current character.
 	beqz t1, .Lread_line_end # Exit the loop on the NUL character.
 	li t2, '\n'
 	beq t1, t2, .Lread_line_end # Exit the loop on the new line.
 
-	addi t0, t0, 1
+	loca0 := loca0 + 1
 	goto .Lread_line_do
 
 	.Lread_line_end
-	sub a0, t0, s1 # Return the line length.
+	loca4 := _current()
+	return loca0 - loca4 (* Return the line length. *)
 end
 
 proc _compile()
+var loca0, loca4: Word
 begin
-	sw zero, 4(sp) # Whether the text section header was already emitted.
+	loca4 := 0 (* Whether the text section header was already emitted. *)
 
 	.Lcompile_do
 	lbu t0, (s1) # t0 = Current character.
 	beqz t0, .Lcompile_end # Exit the loop on the NUL character.
 
 	_skip_indentation()
-	call _read_line
+	loca0 := _read_line()
+	lw a0, 0(sp)
 	lw a1, 4(sp)
 	call _compile_line