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Use the skip list library to manage overwritten instructions in the debugger 

This avoids the quadratic behaviors of the previous array-based
implementation.

Closes: #9606
master
Xavier Leroy 2020-05-30 14:02:45 +02:00
parent 40824de87f
commit 8fd7894b2a
1 changed files with 23 additions and 51 deletions
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74
runtime/debugger.c
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@ -28,6 +28,7 @@
#include "caml/debugger.h"
#include "caml/misc.h"
#include "caml/osdeps.h"
#include "caml/skiplist.h"
int caml_debugger_in_use = 0;
uintnat caml_event_count;
@ -96,7 +97,7 @@ static struct channel * dbg_out;/* Output channel on the socket */
static char *dbg_addr = NULL;
static struct ext_table breakpoints_table;
static struct skiplist event_points_table = SKIPLIST_STATIC_INITIALIZER;
static void open_connection(void)
{
@ -198,8 +199,6 @@ void caml_debugger_init(void)
unsetenv("CAML_DEBUG_SOCKET");
#endif
caml_ext_table_init(&breakpoints_table, 16);
#ifdef _WIN32
winsock_startup();
(void)atexit(winsock_cleanup);
@ -281,38 +280,14 @@ static void safe_output_value(struct channel *chan, value val)
Caml_state->external_raise = saved_external_raise;
}
struct breakpoint {
code_t pc;
opcode_t saved;
};
static struct breakpoint *find_breakpoint(code_t pc)
{
struct breakpoint *bpti;
int i;
for (i = 0; i < breakpoints_table.size; i++) {
bpti = (struct breakpoint *) breakpoints_table.contents[i];
if (bpti->pc == pc)
return bpti;
}
return NULL;
}
static void save_instruction(code_t pc)
{
struct breakpoint *bpt;
if (find_breakpoint(pc) != NULL) {
uintnat saved;
if (caml_skiplist_find(&event_points_table, (uintnat) pc, &saved)) {
/* Already saved. Nothing to do. */
return;
}
bpt = caml_stat_alloc(sizeof(struct breakpoint));
bpt->pc = pc;
bpt->saved = *pc;
caml_ext_table_add(&breakpoints_table, bpt);
caml_skiplist_insert(&event_points_table, (uintnat) pc, *pc);
}
static void set_instruction(code_t pc, opcode_t opcode)
@ -323,11 +298,12 @@ static void set_instruction(code_t pc, opcode_t opcode)
static void restore_instruction(code_t pc)
{
struct breakpoint *bpt = find_breakpoint(pc);
CAMLassert (bpt != NULL);
*pc = bpt->saved;
caml_ext_table_remove(&breakpoints_table, bpt);
CAMLunused_start int found; CAMLunused_end
uintnat saved;
found = caml_skiplist_find(&event_points_table, (uintnat) pc, &saved);
CAMLassert(found);
*pc = saved;
caml_skiplist_remove(&event_points_table, (uintnat) pc);
}
static code_t pc_from_pos(int frag, intnat pos)
@ -344,17 +320,17 @@ static code_t pc_from_pos(int frag, intnat pos)
opcode_t caml_debugger_saved_instruction(code_t pc)
{
struct breakpoint *bpt = find_breakpoint(pc);
CAMLassert (bpt != NULL);
return bpt->saved;
CAMLunused_start int found; CAMLunused_end
uintnat saved;
found = caml_skiplist_find(&event_points_table, (uintnat) pc, &saved);
CAMLassert(found);
return saved;
}
void caml_debugger_code_unloaded(int index)
{
struct code_fragment *cf;
struct breakpoint *bpti;
int i;
char * pc;
if (!caml_debugger_in_use) return;
@ -363,16 +339,12 @@ void caml_debugger_code_unloaded(int index)
cf = (struct code_fragment *) caml_code_fragments_table.contents[index];
for (i = 0; i < breakpoints_table.size; i++) {
bpti = (struct breakpoint *) breakpoints_table.contents[i];
if ((char*) bpti->pc >= cf->code_start && (char*) bpti->pc < cf->code_end) {
caml_ext_table_remove(&breakpoints_table, bpti);
/* caml_ext_table_remove has shifted the next element in place
of the one we just removed. Decrement i for the next
iteration. */
i--;
FOREACH_SKIPLIST_ELEMENT(elt, &event_points_table, {
pc = (char *) elt->key;
if (pc >= cf->code_start && pc < cf->code_end) {
caml_skiplist_remove(&event_points_table, (uintnat) pc);
}
}
})
}
#define Pc(sp) ((code_t)((sp)[0]))
@ -590,7 +562,7 @@ void caml_debugger(enum event_kind event, value param)
void caml_debugger_cleanup_fork(void)
{
/* We could remove all of the breakpoints, but closing the connection
/* We could remove all of the event points, but closing the connection
* means that they'll just be skipped anyway. */
close_connection();
caml_debugger_in_use = 0;