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Further optimize eval and eval-head
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@devyn
devyn committed Aug 15, 2023
1 parent 784ca43 commit 6bf1147
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Showing 4 changed files with 114 additions and 148 deletions.
153 changes: 65 additions & 88 deletions stage1/eval.s
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Original file line number Diff line number Diff line change
Expand Up @@ -18,84 +18,68 @@
# a1 = return value / error details object
.global eval
eval:
addi sp, sp, -0x20
addi sp, sp, -0x18
sd ra, 0x00(sp)
sd s1, 0x08(sp) # s1 = expression to evaluate
sd s2, 0x10(sp) # s2 = local words list
sd s3, 0x18(sp) # cons tail (procedure arglist)
mv s1, a0
mv s2, a1
sd a0, 0x08(sp) # a0 = expression to evaluate
sd a1, 0x10(sp) # a1 = local words list
# check type of expression
beqz s1, .Leval_literal # return literal nil
lwu t1, LISP_OBJECT_TYPE(s1)
beqz a0, .Leval_literal # return literal nil
lwu t1, LISP_OBJECT_TYPE(a0)
li t2, LISP_OBJECT_TYPE_SYMBOL
beq t1, t2, .Leval_symbol # eval symbol just looks it up
li t2, LISP_OBJECT_TYPE_CONS
bne t1, t2, .Leval_literal # anything other than a cons or sym is just returned literally
# destructure the cons to (s1 . s3)
call uncons
mv s1, a1
mv s3, a2
# if it's a cons, we evaluate head first, it should be a procedure
mv a0, s1
mv a1, s2
# evaluate the head from the cons, it should be a procedure
addi a0, sp, 0x08
call acquire_locals
call eval
mv s1, zero # used the head, so set to nil
call eval_head
bnez a0, .Leval_ret # error
# call the (assumed) procedure with the tail of the cons as argument list
mv a0, a1
mv a1, s3
mv a2, s2
# tail call: call_procedure
ld a1, 0x08(sp) # args
ld a2, 0x10(sp) # locals
# restore stack and tail call
ld ra, 0x00(sp)
ld s1, 0x08(sp)
ld s2, 0x10(sp)
ld s3, 0x18(sp)
addi sp, sp, 0x20
addi sp, sp, 0x18
j call_procedure
.Leval_symbol:
# if it's a symbol we just look it up
mv a0, s1
call acquire_object # keep symbol, in case error
mv a1, s2
# look the symbol up in locals
ld a1, 0x10(sp)
sd zero, 0x10(sp) # used
call lookup_var
mv s2, zero # used
beqz a0, .Leval_error_undefined
# release the symbol
mv s2, a1 # save found value
mv a0, s1
call release_object
mv a0, zero # success
mv a1, s2 # found value
mv s1, zero # used
mv s2, zero # used
j .Leval_ret
.Leval_error_undefined:
li a0, EVAL_ERROR_UNDEFINED
mv a1, s1 # saved symbol as error details
mv s1, zero # used
j .Leval_ret
.Leval_literal:
mv a0, zero
mv a1, s1
mv s1, zero # used
# return
li a0, 0 # success
# a1 = found value
.Leval_ret:
# release s1 and s2 if they're still set, since they aren't part of the return value
# release the two values on the stack if they're still set,
# since they aren't part of the return value
addi sp, sp, -0x10
sd a0, 0x00(sp)
sd a1, 0x08(sp)
mv a0, s1
ld a0, 0x18(sp)
call release_object
mv a0, s2
ld a0, 0x20(sp)
call release_object
ld a0, 0x00(sp)
ld a1, 0x08(sp)
ld ra, 0x10(sp)
ld s1, 0x18(sp)
ld s2, 0x20(sp)
ld s3, 0x28(sp)
addi sp, sp, 0x30
addi sp, sp, 0x28
ret
.Leval_error_undefined:
li a0, EVAL_ERROR_UNDEFINED
ld a1, 0x08(sp) # saved symbol as error details
sd zero, 0x08(sp) # used
j .Leval_ret
.Leval_literal:
# do quick return, just release locals
ld a0, 0x10(sp)
call release_object
ld ra, 0x00(sp)
mv a0, zero # ok
ld a1, 0x08(sp)
addi sp, sp, 0x18
ret

# Call before eval to increment refcount on locals (a1)
Expand Down Expand Up @@ -168,67 +152,60 @@ call_procedure:

# Takes the first element of a list and evaluates it
#
# a0 = pointer to structure. pass (list, _), will be written with (head, tail)
# a0 = pointer to pointer to tail - will be overwritten with next tail
# a1 = local words
#
# Return:
#
# a0 = eval error
# a1 = eval error data if error
# a1 = evaluated head or eval error
#
# The pointer will contain (nil, nil) on failure, no further release is necessary
# On error, nil will be written to the tail pointer and the remainder will be released.
.global eval_head
eval_head:
addi sp, sp, -0x28
addi sp, sp, -0x18
sd ra, 0x00(sp)
sd s1, 0x08(sp) # s1 = a0, pointer to structure
sd a0, 0x08(sp) # pointer to pointer to tail
sd a1, 0x10(sp) # locals
mv s1, a0
# uncons the list
ld t0, 0x00(a0)
sd zero, 0x00(a0) # taken
sd zero, 0x08(a0) # clear in case of error
ld t0, (a0)
sd zero, (a0) # taken
mv a0, t0
call uncons
beqz a0, .Leval_head_exc # not a cons
# store the tail
sd a2, 0x08(s1)
ld t0, 0x08(sp)
sd a2, (t0)
# eval head x locals
mv a0, a1
ld a1, 0x10(sp)
sd zero, 0x10(sp) # used
call eval
bnez a0, .Leval_head_err # err
# store evaluated head
sd a1, 0x00(s1)
# set result to ok
sd zero, 0x18(sp)
sd zero, 0x20(sp)
.Leval_head_ret:
addi sp, sp, -0x10
# store result
sd a0, 0x00(sp)
sd a1, 0x08(sp)
# release locals if not used
ld a0, 0x10(sp)
ld a0, 0x20(sp)
call release_object
# release tail if error
ld t0, 0x00(sp)
beqz t0, 1f
ld a0, 0x18(sp)
ld a0, (a0)
call release_object
# restore and return
ld ra, 0x00(sp)
ld s1, 0x08(sp)
ld a0, 0x18(sp)
ld a1, 0x20(sp)
sd zero, (a0)
1:
# restore and return
ld a0, 0x00(sp)
ld a1, 0x08(sp)
ld ra, 0x10(sp)
addi sp, sp, 0x28
ret
.Leval_head_exc:
# set exception
li t0, EVAL_ERROR_EXCEPTION
sd t0, 0x18(sp)
sd zero, 0x20(sp)
j .Leval_head_err_ret
.Leval_head_err:
# store result from eval
sd a0, 0x18(sp)
sd a1, 0x20(sp)
.Leval_head_err_ret:
# release tail if it was set
ld a0, 0x08(s1)
call release_object
sd zero, 0x08(s1) # clear it because we released it
# return
li a0, EVAL_ERROR_EXCEPTION
mv a1, zero
j .Leval_head_ret
15 changes: 6 additions & 9 deletions stage1/init.s
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Original file line number Diff line number Diff line change
Expand Up @@ -50,12 +50,14 @@ start:
li a1, LINE_BUF_LENGTH
call get_line
beqz a0, .Lstart_end
mv a1, a0
la a0, LINE_BUF
mv s4, a0
la s3, LINE_BUF
.Lstart_token_loop:
# line buffer empty, end loop
beqz a1, .Lstart_parse_done
beqz s4, .Lstart_parse_done
# loop through tokens and print them
mv a0, s3
mv a1, s4
call get_token
# make sure token is valid
beqz a0, .Lstart_token_error
Expand All @@ -67,7 +69,7 @@ start:
la a0, PARSER_ARRAY
call parse_token
bgtz a0, .Lstart_eval # value produced
beqz a0, .Lstart_token_loop_next # ok but nothing produced
beqz a0, .Lstart_token_loop # ok but nothing produced
# some kind of error
li t0, PARSER_STATUS_OVERFLOW
beq a0, t0, .Lstart_token_overflow
Expand Down Expand Up @@ -147,11 +149,6 @@ start:
call putc
li a0, '\n'
call putc
.Lstart_token_loop_next:
# restore the remaining line buffer to a0-a1 and loop
mv a0, s3
mv a1, s4
j .Lstart_token_loop
.Lstart_parse_done:
j .Lstart_repl
.Lstart_token_overflow:
Expand Down
29 changes: 14 additions & 15 deletions stage1/proc_builtin.s
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Original file line number Diff line number Diff line change
Expand Up @@ -450,18 +450,18 @@ proc_cdr:
.global proc_cons
proc_cons:
# reserve stack, preserve return addr
addi sp, sp, -0x28
addi sp, sp, -0x20
sd ra, 0x00(sp)
sd a1, 0x08(sp) # locals
sd a0, 0x10(sp) # cons head
sd zero, 0x18(sp) # cons tail
sd zero, 0x20(sp) # unused args
sd zero, 0x10(sp) # cons head
sd a0, 0x18(sp) # remaining args
# evaluate first two args
# arg 0 (head)
addi a0, sp, 0x10
addi a0, sp, 0x18
call acquire_locals
call eval_head
bnez a0, .Lproc_cons_ret
sd a1, 0x10(sp)
# arg 1 (tail)
addi a0, sp, 0x18
ld a1, 0x08(sp) # locals
Expand All @@ -470,9 +470,8 @@ proc_cons:
bnez a0, .Lproc_cons_ret
# cons head, tail
ld a0, 0x10(sp)
ld a1, 0x18(sp)
# a1 = tail, from eval
sd zero, 0x10(sp) # used
sd zero, 0x18(sp) # used
call cons
beqz a0, .Lproc_cons_no_mem
mv a1, a0 # result
Expand All @@ -482,20 +481,18 @@ proc_cons:
addi sp, sp, -0x10
sd a0, 0x00(sp)
sd a1, 0x08(sp)
# release from 0x18 .. 0x38 (sp)
# release from 0x18 .. 0x30 (sp)
ld a0, 0x18(sp)
call release_object
ld a0, 0x20(sp)
call release_object
ld a0, 0x28(sp)
call release_object
ld a0, 0x30(sp)
call release_object
# load stashed data and return
ld a0, 0x00(sp)
ld a1, 0x08(sp)
ld ra, 0x10(sp)
addi sp, sp, 0x38
addi sp, sp, 0x30
ret
.Lproc_cons_no_mem:
li a0, EVAL_ERROR_NO_FREE_MEM
Expand Down Expand Up @@ -631,20 +628,22 @@ proc_eval:
addi sp, sp, -0x28
sd ra, 0x00(sp)
sd a1, 0x08(sp) # locals (in)
sd a0, 0x10(sp) # arg 0 = provided locals
sd zero, 0x10(sp) # arg 0 = provided locals
sd zero, 0x18(sp) # arg 1 = expression
sd zero, 0x20(sp) # unused args
sd a0, 0x20(sp) # remaining args
# arg 0
addi a0, sp, 0x10
addi a0, sp, 0x20
call acquire_locals
call eval_head
bnez a0, .Lproc_eval_error
sd a1, 0x10(sp)
# arg 1
addi a0, sp, 0x18
addi a0, sp, 0x20
ld a1, 0x08(sp) # locals
sd zero, 0x08(sp) # used
call eval_head
bnez a0, .Lproc_eval_error
sd a1, 0x18(sp)
# release rest of args
ld a0, 0x20(sp)
call release_object
Expand Down
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