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author | Andy Wingo <wingo@pobox.com> | 2014-04-14 16:31:02 +0200 |
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committer | Andy Wingo <wingo@pobox.com> | 2014-04-14 16:31:02 +0200 |
commit | 3b14dd2f272920854565011d82b41df1237a2213 (patch) | |
tree | e336aaa9e7865db533ac003a8193c377b9aa6436 /libguile/stacks.c | |
parent | 8de051da47e8f0f56a13bde6a4b37ece5f9c81cf (diff) | |
download | guile-3b14dd2f272920854565011d82b41df1237a2213.tar.gz |
Optimize make-stack
* libguile/continuations.h:
* libguile/continuations.c (scm_i_continuation_to_frame): Operate on
low-level C structures instead of heap objects.
* libguile/frames.h:
* libguile/frames.c (frame_offset, frame_stack_base): Const args.
(scm_c_frame_closure): New helper.
(scm_frame_procedure): Use the new helper.
* libguile/stacks.c (stack_depth, narrow_stack, scm_make_stack): Rework
to avoid allocating frames as we traverse the stack, and to avoid an
n**2 case where there are outer cuts.
Diffstat (limited to 'libguile/stacks.c')
-rw-r--r-- | libguile/stacks.c | 135 |
1 files changed, 69 insertions, 66 deletions
diff --git a/libguile/stacks.c b/libguile/stacks.c index 8837a7fe2..182d35751 100644 --- a/libguile/stacks.c +++ b/libguile/stacks.c @@ -65,11 +65,12 @@ static SCM scm_sys_stacks; /* Count number of debug info frames on a stack, beginning with FRAME. */ static long -stack_depth (SCM frame) +stack_depth (enum scm_vm_frame_kind kind, const struct scm_frame *frame) { - long n = 0; - /* count frames, skipping boot frames */ - for (; scm_is_true (frame); frame = scm_frame_previous (frame)) + struct scm_frame tmp; + long n = 1; + memcpy (&tmp, frame, sizeof tmp); + while (scm_c_frame_previous (kind, &tmp)) ++n; return n; } @@ -108,24 +109,19 @@ find_prompt (SCM key) return fp_offset; } -static void -narrow_stack (SCM stack, SCM inner_cut, SCM outer_cut) +static long +narrow_stack (long len, enum scm_vm_frame_kind kind, struct scm_frame *frame, + SCM inner_cut, SCM outer_cut) { - unsigned long int len; - SCM frame; - - len = SCM_STACK_LENGTH (stack); - frame = SCM_STACK_FRAME (stack); - /* Cut inner part. */ if (scm_is_true (scm_procedure_p (inner_cut))) { /* Cut until the given procedure is seen. */ for (; len ;) { - SCM proc = scm_frame_procedure (frame); + SCM proc = scm_c_frame_closure (kind, frame); len--; - frame = scm_frame_previous (frame); + scm_c_frame_previous (kind, frame); if (scm_is_eq (proc, inner_cut)) break; } @@ -138,32 +134,32 @@ narrow_stack (SCM stack, SCM inner_cut, SCM outer_cut) for (; inner && len; --inner) { len--; - frame = scm_frame_previous (frame); + scm_c_frame_previous (kind, frame); } } else { /* Cut until the given prompt tag is seen. */ scm_t_ptrdiff fp_offset = find_prompt (inner_cut); - for (; len; len--, frame = scm_frame_previous (frame)) - if (fp_offset == SCM_VM_FRAME_FP_OFFSET (frame)) + for (; len; len--, scm_c_frame_previous (kind, frame)) + if (fp_offset == frame->fp_offset) break; } - SCM_SET_STACK_LENGTH (stack, len); - SCM_SET_STACK_FRAME (stack, frame); - /* Cut outer part. */ if (scm_is_true (scm_procedure_p (outer_cut))) { + long i, new_len; + struct scm_frame tmp; + + memcpy (&tmp, frame, sizeof tmp); + /* Cut until the given procedure is seen. */ - for (; len ;) - { - frame = scm_stack_ref (stack, scm_from_long (len - 1)); - len--; - if (scm_is_eq (scm_frame_procedure (frame), outer_cut)) - break; - } + for (new_len = i = 0; i < len; i++, scm_c_frame_previous (kind, &tmp)) + if (scm_is_eq (scm_c_frame_closure (kind, &tmp), outer_cut)) + new_len = i; + + len = new_len; } else if (scm_is_integer (outer_cut)) { @@ -178,17 +174,23 @@ narrow_stack (SCM stack, SCM inner_cut, SCM outer_cut) else { /* Cut until the given prompt tag is seen. */ + long i; + struct scm_frame tmp; scm_t_ptrdiff fp_offset = find_prompt (outer_cut); - while (len) - { - frame = scm_stack_ref (stack, scm_from_long (len - 1)); - len--; - if (fp_offset == SCM_VM_FRAME_FP_OFFSET (frame)) - break; - } + + memcpy (&tmp, frame, sizeof tmp); + + for (i = 0; i < len; i++, scm_c_frame_previous (kind, &tmp)) + if (tmp.fp_offset == fp_offset) + break; + + if (i < len) + len = i; + else + len = 0; } - SCM_SET_STACK_LENGTH (stack, len); + return len; } @@ -244,9 +246,9 @@ SCM_DEFINE (scm_make_stack, "make-stack", 1, 0, 1, #define FUNC_NAME s_scm_make_stack { long n; - SCM frame; - SCM stack; SCM inner_cut, outer_cut; + enum scm_vm_frame_kind kind; + struct scm_frame frame; /* Extract a pointer to the innermost frame of whatever object scm_make_stack was given. */ @@ -254,49 +256,47 @@ SCM_DEFINE (scm_make_stack, "make-stack", 1, 0, 1, { SCM cont; struct scm_vm_cont *c; - struct scm_frame tmp; cont = scm_i_capture_current_stack (); - c = SCM_VM_CONT_DATA (cont); - tmp.stack_holder = c; - tmp.fp_offset = (c->fp + c->reloc) - c->stack_base; - tmp.sp_offset = (c->sp + c->reloc) - c->stack_base; - tmp.ip = c->ra; - frame = scm_c_make_frame (SCM_VM_FRAME_KIND_CONT, &tmp); + + kind = SCM_VM_FRAME_KIND_CONT; + frame.stack_holder = c; + frame.fp_offset = (c->fp + c->reloc) - c->stack_base; + frame.sp_offset = (c->sp + c->reloc) - c->stack_base; + frame.ip = c->ra; } else if (SCM_VM_FRAME_P (obj)) - frame = obj; + { + kind = SCM_VM_FRAME_KIND (obj); + memcpy (&frame, SCM_VM_FRAME_DATA (obj), sizeof frame); + } else if (SCM_CONTINUATIONP (obj)) /* FIXME: Narrowing to prompt tags should narrow with respect to the prompts that were in place when the continuation was captured. */ - frame = scm_i_continuation_to_frame (obj); + { + kind = SCM_VM_FRAME_KIND_CONT; + if (!scm_i_continuation_to_frame (obj, &frame)) + return SCM_BOOL_F; + } else { SCM_WRONG_TYPE_ARG (SCM_ARG1, obj); /* not reached */ } - /* FIXME: is this even possible? */ - if (scm_is_true (frame) - && SCM_PROGRAM_P (scm_frame_procedure (frame)) - && SCM_PROGRAM_IS_BOOT (scm_frame_procedure (frame))) - frame = scm_frame_previous (frame); - - if (scm_is_false (frame)) + /* Skip initial boot frame, if any. This is possible if the frame + originates from a captured continuation. */ + if (SCM_PROGRAM_P (scm_c_frame_closure (kind, &frame)) + && SCM_PROGRAM_IS_BOOT (scm_c_frame_closure (kind, &frame)) + && !scm_c_frame_previous (kind, &frame)) return SCM_BOOL_F; /* Count number of frames. Also get stack id tag and check whether there are more stackframes than we want to record (SCM_BACKTRACE_MAXDEPTH). */ - n = stack_depth (frame); + n = stack_depth (kind, &frame); - /* Make the stack object. */ - stack = scm_make_struct (scm_stack_type, SCM_INUM0, SCM_EOL); - SCM_SET_STACK_LENGTH (stack, n); - SCM_SET_STACK_ID (stack, scm_stack_id (obj)); - SCM_SET_STACK_FRAME (stack, frame); - /* Narrow the stack according to the arguments given to scm_make_stack. */ SCM_VALIDATE_REST_ARGUMENT (args); while (n > 0 && !scm_is_null (args)) @@ -313,15 +313,18 @@ SCM_DEFINE (scm_make_stack, "make-stack", 1, 0, 1, args = SCM_CDR (args); } - narrow_stack (stack, - inner_cut, - outer_cut); - - n = SCM_STACK_LENGTH (stack); + n = narrow_stack (n, kind, &frame, inner_cut, outer_cut); } if (n > 0) - return stack; + { + /* Make the stack object. */ + SCM stack = scm_make_struct (scm_stack_type, SCM_INUM0, SCM_EOL); + SCM_SET_STACK_LENGTH (stack, n); + SCM_SET_STACK_ID (stack, scm_stack_id (obj)); + SCM_SET_STACK_FRAME (stack, scm_c_make_frame (kind, &frame)); + return stack; + } else return SCM_BOOL_F; } |