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fix native-stack caching with libunwind

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The implementation of caching stack-trace information in the
stack didn't work right in libunwind mode, with the result that
`(current-continuatiom-marks)` took O(N) time for a continuation
of size N, when it should be amortized constant time.
This commit is contained in:
Matthew Flatt 2014-12-14 08:43:52 -07:00
parent 58ef3fdaa8
commit d15fda9d6b
1 changed files with 10 additions and 5 deletions
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15
racket/src/racket/src/jitstack.c
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@ -161,7 +161,7 @@ static void set_cache(void *p, Scheme_Object *last)
Scheme_Object *scheme_native_stack_trace(void) Scheme_Object *scheme_native_stack_trace(void)
{ {
void *p, *q; void *p, *q, *prev_frame_p;
uintptr_t stack_end, real_stack_end, stack_start, halfway; uintptr_t stack_end, real_stack_end, stack_start, halfway;
Scheme_Object *name, *last = NULL, *first = NULL, *tail; Scheme_Object *name, *last = NULL, *first = NULL, *tail;
int prev_had_name = 0; int prev_had_name = 0;
@ -208,12 +208,12 @@ Scheme_Object *scheme_native_stack_trace(void)
p = gs(); p = gs();
#endif #endif
halfway = STK_DIFF(stack_end, (uintptr_t)p) / 2; halfway = STK_DIFF(stack_end, (uintptr_t)stack_start) / 2;
if (halfway < CACHE_STACK_MIN_TRIGGER) if (halfway < CACHE_STACK_MIN_TRIGGER)
halfway = stack_end; halfway = stack_end;
else { else {
#ifdef STACK_GROWS_DOWN #ifdef STACK_GROWS_DOWN
halfway += (uintptr_t)p; halfway += (uintptr_t)stack_start;
#else #else
halfway += stack_end; halfway += stack_end;
#endif #endif
@ -318,6 +318,8 @@ Scheme_Object *scheme_native_stack_trace(void)
} }
#endif #endif
prev_frame_p = NULL;
while (unsuccess < UNKNOWN_FRAME_LIMIT) { while (unsuccess < UNKNOWN_FRAME_LIMIT) {
#ifdef MZ_USE_DWARF_LIBUNWIND #ifdef MZ_USE_DWARF_LIBUNWIND
if (use_unw) { if (use_unw) {
@ -431,9 +433,9 @@ Scheme_Object *scheme_native_stack_trace(void)
might not be used (depending on how the C compiler optimized the might not be used (depending on how the C compiler optimized the
code); any frame whose procedure has a name is JITted code, so code); any frame whose procedure has a name is JITted code, so
it will use the return address from the stack. */ it will use the return address from the stack. */
if (STK_COMP((uintptr_t)halfway, (uintptr_t)p) if (STK_COMP((uintptr_t)halfway, (uintptr_t)prev_frame_p)
&& prev_had_name) { && prev_had_name) {
set_cache(p, last); set_cache(prev_frame_p, last);
if (!added_list_elem) if (!added_list_elem)
shift_cache_to_next = 1; shift_cache_to_next = 1;
halfway = stack_end; halfway = stack_end;
@ -451,6 +453,7 @@ Scheme_Object *scheme_native_stack_trace(void)
if (!(STK_COMP((uintptr_t)pp, stack_end) if (!(STK_COMP((uintptr_t)pp, stack_end)
&& STK_COMP(stack_start, (uintptr_t)pp))) && STK_COMP(stack_start, (uintptr_t)pp)))
break; break;
prev_frame_p = pp;
# ifdef MZ_USE_JIT_ARM # ifdef MZ_USE_JIT_ARM
stack_addr = (unw_word_t)&(pp[JIT_NEXT_FP_OFFSET+2]); stack_addr = (unw_word_t)&(pp[JIT_NEXT_FP_OFFSET+2]);
unw_manual_step(&c, unw_manual_step(&c,
@ -465,6 +468,7 @@ Scheme_Object *scheme_native_stack_trace(void)
# endif # endif
manual_unw = 0; manual_unw = 0;
} else { } else {
prev_frame_p = NULL;
unw_step(&c); unw_step(&c);
q = (void *)unw_get_ip(&c); q = (void *)unw_get_ip(&c);
if (unw_reset_bad_ptr_flag(&c)) if (unw_reset_bad_ptr_flag(&c))
@ -478,6 +482,7 @@ Scheme_Object *scheme_native_stack_trace(void)
if (STK_COMP((uintptr_t)q, (uintptr_t)p)) if (STK_COMP((uintptr_t)q, (uintptr_t)p))
break; break;
p = q; p = q;
prev_frame_p = p;
} }
} }