Propagate error in mono_unicode_to_external (#14879)

[mono-project.git] / mono / mini / debugger-engine.c

/**
 * \file
 * Debugger Engine shared code.
 *
 * Author:
 *   Zoltan Varga (vargaz@gmail.com)
 *   Rodrigo Kumpera (kumpera@gmail.com)
 *
 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
 */

#include <config.h>
#include "mini-runtime.h"

#if !defined (DISABLE_SDB) || defined(TARGET_WASM)

#include <glib.h>
#include "seq-points.h"
#include "aot-runtime.h"
#include "debugger-engine.h"
#include "debugger-state-machine.h"
#include <mono/metadata/debug-internals.h>

static void mono_de_ss_start (SingleStepReq *ss_req, SingleStepArgs *ss_args);
static gboolean mono_de_ss_update (SingleStepReq *req, MonoJitInfo *ji, SeqPoint *sp, void *tls, MonoContext *ctx, MonoMethod* method);


static DebuggerEngineCallbacks rt_callbacks;

/*
 * Logging support
 */
static int log_level;
static FILE *log_file;

#ifdef HOST_ANDROID
#define DEBUG_PRINTF(level, ...) do { if (G_UNLIKELY ((level) <= log_level)) { g_print (__VA_ARGS__); } } while (0)
#else
#define DEBUG_PRINTF(level, ...) do { if (G_UNLIKELY ((level) <= log_level)) { fprintf (log_file, __VA_ARGS__); fflush (log_file); } } while (0)
#endif

/*
 * Locking
 */
#define dbg_lock() mono_coop_mutex_lock (&debug_mutex)
#define dbg_unlock() mono_coop_mutex_unlock (&debug_mutex)
static MonoCoopMutex debug_mutex;

void
mono_de_lock (void)
{
        dbg_lock ();
}

void
mono_de_unlock (void)
{
        dbg_unlock ();
}


/*
 * Domain support
 */


/* A hash table containing all active domains */
/* Protected by the loader lock */
static GHashTable *domains;


static void
domains_init (void)
{
        domains = g_hash_table_new (mono_aligned_addr_hash, NULL);
}

static void
domains_cleanup (void)
{
        //FIXME can we safely destroy `domains`?
}

/*
 * mono_de_foreach_domain:
 *
 * Iterate over all domains under debugging. Caller must take the loader lock.
 *
 * FIXME can we move the locking to here? Callers in sdb must be properly audited.
 */
void
mono_de_foreach_domain (GHFunc func, gpointer user_data)
{
        g_hash_table_foreach (domains, func, user_data);
}

/*
 * LOCKING: Takes the loader lock
 */
void
mono_de_domain_remove (MonoDomain *domain)
{
        mono_loader_lock ();
        g_hash_table_remove (domains, domain);
        mono_loader_unlock ();
}

/*
 * LOCKING: Takes the loader lock
 */
void
mono_de_domain_add (MonoDomain *domain)
{
        mono_loader_lock ();
        g_hash_table_insert (domains, domain, domain);
        mono_loader_unlock ();
}

/*
 * BREAKPOINTS
 */

/* List of breakpoints */
/* Protected by the loader lock */
static GPtrArray *breakpoints;
/* Maps breakpoint locations to the number of breakpoints at that location */
static GHashTable *bp_locs;

static void
breakpoints_init (void)
{
        breakpoints = g_ptr_array_new ();
        bp_locs = g_hash_table_new (NULL, NULL);
}

/*
 * insert_breakpoint:
 *
 *   Insert the breakpoint described by BP into the method described by
 * JI.
 */
static void
insert_breakpoint (MonoSeqPointInfo *seq_points, MonoDomain *domain, MonoJitInfo *ji, MonoBreakpoint *bp, MonoError *error)
{
        int count;
        BreakpointInstance *inst;
        SeqPointIterator it;
        gboolean it_has_sp = FALSE;

        if (error)
                error_init (error);

        mono_seq_point_iterator_init (&it, seq_points);
        while (mono_seq_point_iterator_next (&it)) {
                if (it.seq_point.il_offset == bp->il_offset) {
                        it_has_sp = TRUE;
                        break;
                }
        }

        if (!it_has_sp) {
                /*
                 * The set of IL offsets with seq points doesn't completely match the
                 * info returned by CMD_METHOD_GET_DEBUG_INFO (#407).
                 */
                mono_seq_point_iterator_init (&it, seq_points);
                while (mono_seq_point_iterator_next (&it)) {
                        if (it.seq_point.il_offset != METHOD_ENTRY_IL_OFFSET &&
                                it.seq_point.il_offset != METHOD_EXIT_IL_OFFSET &&
                                it.seq_point.il_offset + 1 == bp->il_offset) {
                                it_has_sp = TRUE;
                                break;
                        }
                }
        }

        if (!it_has_sp) {
                char *s = g_strdup_printf ("Unable to insert breakpoint at %s:%ld", mono_method_full_name (jinfo_get_method (ji), TRUE), bp->il_offset);

                mono_seq_point_iterator_init (&it, seq_points);
                while (mono_seq_point_iterator_next (&it))
                        DEBUG_PRINTF (1, "%d\n", it.seq_point.il_offset);

                if (error) {
                        mono_error_set_error (error, MONO_ERROR_GENERIC, "%s", s);
                        g_warning ("%s", s);
                        g_free (s);
                        return;
                } else {
                        g_warning ("%s", s);
                        g_free (s);
                        return;
                }
        }

        inst = g_new0 (BreakpointInstance, 1);
        inst->il_offset = it.seq_point.il_offset;
        inst->native_offset = it.seq_point.native_offset;
        inst->ip = (guint8*)ji->code_start + it.seq_point.native_offset;
        inst->ji = ji;
        inst->domain = domain;

        mono_loader_lock ();

        g_ptr_array_add (bp->children, inst);

        mono_loader_unlock ();

        dbg_lock ();
        count = GPOINTER_TO_INT (g_hash_table_lookup (bp_locs, inst->ip));
        g_hash_table_insert (bp_locs, inst->ip, GINT_TO_POINTER (count + 1));
        dbg_unlock ();

        if (it.seq_point.native_offset == SEQ_POINT_NATIVE_OFFSET_DEAD_CODE) {
                DEBUG_PRINTF (1, "[dbg] Attempting to insert seq point at dead IL offset %d, ignoring.\n", (int)bp->il_offset);
        } else if (count == 0) {
                if (ji->is_interp) {
                        mini_get_interp_callbacks ()->set_breakpoint (ji, inst->ip);
                } else {
#ifdef MONO_ARCH_SOFT_DEBUG_SUPPORTED
                        mono_arch_set_breakpoint (ji, inst->ip);
#else
                        NOT_IMPLEMENTED;
#endif
                }
        }

        DEBUG_PRINTF (1, "[dbg] Inserted breakpoint at %s:[il=0x%x,native=0x%x] [%p](%d).\n", mono_method_full_name (jinfo_get_method (ji), TRUE), (int)it.seq_point.il_offset, (int)it.seq_point.native_offset, inst->ip, count);
}

static void
remove_breakpoint (BreakpointInstance *inst)
{
        int count;
        MonoJitInfo *ji = inst->ji;
        guint8 *ip = inst->ip;

        dbg_lock ();
        count = GPOINTER_TO_INT (g_hash_table_lookup (bp_locs, ip));
        g_hash_table_insert (bp_locs, ip, GINT_TO_POINTER (count - 1));
        dbg_unlock ();

        g_assert (count > 0);

        if (count == 1 && inst->native_offset != SEQ_POINT_NATIVE_OFFSET_DEAD_CODE) {
                if (ji->is_interp) {
                        mini_get_interp_callbacks ()->clear_breakpoint (ji, ip);
                } else {
#ifdef MONO_ARCH_SOFT_DEBUG_SUPPORTED
                        mono_arch_clear_breakpoint (ji, ip);
#else
                        NOT_IMPLEMENTED;
#endif
                }
                DEBUG_PRINTF (1, "[dbg] Clear breakpoint at %s [%p].\n", mono_method_full_name (jinfo_get_method (ji), TRUE), ip);
        }
}

/*
 * This doesn't take any locks.
 */
static inline gboolean
bp_matches_method (MonoBreakpoint *bp, MonoMethod *method)
{
        int i;

        if (!bp->method)
                return TRUE;
        if (method == bp->method)
                return TRUE;
        if (method->is_inflated && ((MonoMethodInflated*)method)->declaring == bp->method)
                return TRUE;

        if (bp->method->is_inflated && method->is_inflated) {
                MonoMethodInflated *bpimethod = (MonoMethodInflated*)bp->method;
                MonoMethodInflated *imethod = (MonoMethodInflated*)method;

                /* Open generic methods should match closed generic methods of the same class */
                if (bpimethod->declaring == imethod->declaring && bpimethod->context.class_inst == imethod->context.class_inst && bpimethod->context.method_inst && bpimethod->context.method_inst->is_open) {
                        for (i = 0; i < bpimethod->context.method_inst->type_argc; ++i) {
                                MonoType *t1 = bpimethod->context.method_inst->type_argv [i];

                                /* FIXME: Handle !mvar */
                                if (t1->type != MONO_TYPE_MVAR)
                                        return FALSE;
                        }
                        return TRUE;
                }
        }

        return FALSE;
}

/*
 * mono_de_add_pending_breakpoints:
 *
 *   Insert pending breakpoints into the newly JITted method METHOD.
 */
void
mono_de_add_pending_breakpoints (MonoMethod *method, MonoJitInfo *ji)
{
        int i, j;
        MonoSeqPointInfo *seq_points;
        MonoDomain *domain;

        if (!breakpoints)
                return;

        domain = mono_domain_get ();

        mono_loader_lock ();

        for (i = 0; i < breakpoints->len; ++i) {
                MonoBreakpoint *bp = (MonoBreakpoint *)g_ptr_array_index (breakpoints, i);
                gboolean found = FALSE;

                if (!bp_matches_method (bp, method))
                        continue;

                for (j = 0; j < bp->children->len; ++j) {
                        BreakpointInstance *inst = (BreakpointInstance *)g_ptr_array_index (bp->children, j);

                        if (inst->ji == ji)
                                found = TRUE;
                }

                if (!found) {
                        seq_points = (MonoSeqPointInfo *) ji->seq_points;

                        if (!seq_points) {
                                MonoMethod *jmethod = jinfo_get_method (ji);
                                if (jmethod->is_inflated) {
                                        MonoJitInfo *seq_ji;
                                        MonoMethod *declaring = mono_method_get_declaring_generic_method (jmethod);
                                        mono_jit_search_all_backends_for_jit_info (domain, declaring, &seq_ji);
                                        seq_points = (MonoSeqPointInfo *) seq_ji->seq_points;
                                }
                        }

                        if (!seq_points)
                                /* Could be AOT code, or above "search_all_backends" call could have failed */
                                continue;

                        insert_breakpoint (seq_points, domain, ji, bp, NULL);
                }
        }

        mono_loader_unlock ();
}

static void
set_bp_in_method (MonoDomain *domain, MonoMethod *method, MonoSeqPointInfo *seq_points, MonoBreakpoint *bp, MonoError *error)
{
        gpointer code;
        MonoJitInfo *ji;

        if (error)
                error_init (error);

        code = mono_jit_search_all_backends_for_jit_info (domain, method, &ji);
        g_assert (ji);

        insert_breakpoint (seq_points, domain, ji, bp, error);
}

typedef struct {
        MonoBreakpoint *bp;
        GPtrArray *methods;
        GPtrArray *method_domains;
        GPtrArray *method_seq_points;
} CollectDomainData;

static void
collect_domain_bp (gpointer key, gpointer value, gpointer user_data)
{
        GHashTableIter iter;
        MonoSeqPointInfo *seq_points;
        MonoDomain *domain = (MonoDomain*)key;
        CollectDomainData *ud = (CollectDomainData*)user_data;
        MonoMethod *m;

        mono_domain_lock (domain);
        g_hash_table_iter_init (&iter, domain_jit_info (domain)->seq_points);
        while (g_hash_table_iter_next (&iter, (void**)&m, (void**)&seq_points)) {
                if (bp_matches_method (ud->bp, m)) {
                        /* Save the info locally to simplify the code inside the domain lock */
                        g_ptr_array_add (ud->methods, m);
                        g_ptr_array_add (ud->method_domains, domain);
                        g_ptr_array_add (ud->method_seq_points, seq_points);
                }
        }
        mono_domain_unlock (domain);
}

void
mono_de_clear_all_breakpoints (void)
{
        while (breakpoints->len)
                mono_de_clear_breakpoint ((MonoBreakpoint*)g_ptr_array_index (breakpoints, 0));
}

/*
 * mono_de_set_breakpoint:
 *
 *   Set a breakpoint at IL_OFFSET in METHOD.
 * METHOD can be NULL, in which case a breakpoint is placed in all methods.
 * METHOD can also be a generic method definition, in which case a breakpoint
 * is placed in all instances of the method.
 * If ERROR is non-NULL, then it is set and NULL is returnd if some breakpoints couldn't be
 * inserted.
 */
MonoBreakpoint*
mono_de_set_breakpoint (MonoMethod *method, long il_offset, EventRequest *req, MonoError *error)
{
        MonoBreakpoint *bp;
        MonoDomain *domain;
        MonoMethod *m;
        MonoSeqPointInfo *seq_points;
        GPtrArray *methods;
        GPtrArray *method_domains;
        GPtrArray *method_seq_points;
        int i;

        if (error)
                error_init (error);

        // FIXME:
        // - suspend/resume the vm to prevent code patching problems
        // - multiple breakpoints on the same location
        // - dynamic methods
        // - races

        bp = g_new0 (MonoBreakpoint, 1);
        bp->method = method;
        bp->il_offset = il_offset;
        bp->req = req;
        bp->children = g_ptr_array_new ();

        DEBUG_PRINTF (1, "[dbg] Setting %sbreakpoint at %s:0x%x.\n", (req->event_kind == EVENT_KIND_STEP) ? "single step " : "", method ? mono_method_full_name (method, TRUE) : "<all>", (int)il_offset);

        methods = g_ptr_array_new ();
        method_domains = g_ptr_array_new ();
        method_seq_points = g_ptr_array_new ();

        mono_loader_lock ();

        CollectDomainData user_data;
        memset (&user_data, 0, sizeof (user_data));
        user_data.bp = bp;
        user_data.methods = methods;
        user_data.method_domains = method_domains;
        user_data.method_seq_points = method_seq_points;
        mono_de_foreach_domain (collect_domain_bp, &user_data);

        for (i = 0; i < methods->len; ++i) {
                m = (MonoMethod *)g_ptr_array_index (methods, i);
                domain = (MonoDomain *)g_ptr_array_index (method_domains, i);
                seq_points = (MonoSeqPointInfo *)g_ptr_array_index (method_seq_points, i);
                set_bp_in_method (domain, m, seq_points, bp, error);
        }

        g_ptr_array_add (breakpoints, bp);
        mono_debugger_log_add_bp (bp, bp->method, bp->il_offset);
        mono_loader_unlock ();

        g_ptr_array_free (methods, TRUE);
        g_ptr_array_free (method_domains, TRUE);
        g_ptr_array_free (method_seq_points, TRUE);

        if (error && !mono_error_ok (error)) {
                mono_de_clear_breakpoint (bp);
                return NULL;
        }

        return bp;
}

MonoBreakpoint *
mono_de_get_breakpoint_by_id (int id)
{
        for (int i = 0; i < breakpoints->len; ++i) {
                MonoBreakpoint *bp = (MonoBreakpoint *)g_ptr_array_index (breakpoints, i);
                if (bp->req->id == id)
                        return bp;
        }
        return NULL;
}

void
mono_de_clear_breakpoint (MonoBreakpoint *bp)
{
        int i;

        // FIXME: locking, races
        for (i = 0; i < bp->children->len; ++i) {
                BreakpointInstance *inst = (BreakpointInstance *)g_ptr_array_index (bp->children, i);

                remove_breakpoint (inst);

                g_free (inst);
        }

        mono_loader_lock ();
        mono_debugger_log_remove_bp (bp, bp->method, bp->il_offset);
        g_ptr_array_remove (breakpoints, bp);
        mono_loader_unlock ();

        g_ptr_array_free (bp->children, TRUE);
        g_free (bp);
}

void
mono_de_collect_breakpoints_by_sp (SeqPoint *sp, MonoJitInfo *ji, GPtrArray *ss_reqs, GPtrArray *bp_reqs)
{
        for (int i = 0; i < breakpoints->len; ++i) {
                MonoBreakpoint *bp = (MonoBreakpoint *)g_ptr_array_index (breakpoints, i);

                if (!bp->method)
                        continue;

                for (int j = 0; j < bp->children->len; ++j) {
                        BreakpointInstance *inst = (BreakpointInstance *)g_ptr_array_index (bp->children, j);
                        if (inst->ji == ji && inst->il_offset == sp->il_offset && inst->native_offset == sp->native_offset) {
                                if (bp->req->event_kind == EVENT_KIND_STEP) {
                                        if (ss_reqs)
                                                g_ptr_array_add (ss_reqs, bp->req);
                                } else {
                                        if (bp_reqs)
                                                g_ptr_array_add (bp_reqs, bp->req);
                                }
                        }
                }
                }
}

static void
breakpoints_cleanup (void)
{
        int i;

        mono_loader_lock ();

        for (i = 0; i < breakpoints->len; ++i)
                g_free (g_ptr_array_index (breakpoints, i));

        g_ptr_array_free (breakpoints, TRUE);
        g_hash_table_destroy (bp_locs);

        breakpoints = NULL;
        bp_locs = NULL;

        mono_loader_unlock ();
}

/*
 * mono_de_clear_breakpoints_for_domain:
 *
 *   Clear breakpoint instances which reference DOMAIN.
 */
void
mono_de_clear_breakpoints_for_domain (MonoDomain *domain)
{
        int i, j;

        /* This could be called after shutdown */
        if (!breakpoints)
                return;

        mono_loader_lock ();
        for (i = 0; i < breakpoints->len; ++i) {
                MonoBreakpoint *bp = (MonoBreakpoint *)g_ptr_array_index (breakpoints, i);

                j = 0;
                while (j < bp->children->len) {
                        BreakpointInstance *inst = (BreakpointInstance *)g_ptr_array_index (bp->children, j);

                        if (inst->domain == domain) {
                                remove_breakpoint (inst);

                                g_free (inst);

                                g_ptr_array_remove_index_fast (bp->children, j);
                        } else {
                                j ++;
                        }
                }
        }
        mono_loader_unlock ();
}

/* Single stepping engine */
/* Number of single stepping operations in progress */
static int ss_count;

/* The single step request instance */
static SingleStepReq *the_ss_req;

/*
 * mono_de_start_single_stepping:
 *
 *   Turn on single stepping. Can be called multiple times, for example,
 * by a single step event request + a suspend.
 */
void
mono_de_start_single_stepping (void)
{
        int val = mono_atomic_inc_i32 (&ss_count);

        if (val == 1) {
#ifdef MONO_ARCH_SOFT_DEBUG_SUPPORTED
                mono_arch_start_single_stepping ();
#endif
                mini_get_interp_callbacks ()->start_single_stepping ();
        }
}

void
mono_de_stop_single_stepping (void)
{
        int val = mono_atomic_dec_i32 (&ss_count);

        if (val == 0) {
#ifdef MONO_ARCH_SOFT_DEBUG_SUPPORTED
                mono_arch_stop_single_stepping ();
#endif
                mini_get_interp_callbacks ()->stop_single_stepping ();
        }
}

static MonoJitInfo*
get_top_method_ji (gpointer ip, MonoDomain **domain, gpointer *out_ip)
{
        MonoJitInfo *ji;

        if (out_ip)
                *out_ip = ip;

        ji = mini_jit_info_table_find (mono_domain_get (), (char*)ip, domain);
        if (!ji) {
                /* Could be an interpreter method */

                MonoLMF *lmf = mono_get_lmf ();
                MonoInterpFrameHandle *frame;

                g_assert (((gsize)lmf->previous_lmf) & 2);
                MonoLMFExt *ext = (MonoLMFExt*)lmf;

                g_assert (ext->kind == MONO_LMFEXT_INTERP_EXIT || ext->kind == MONO_LMFEXT_INTERP_EXIT_WITH_CTX);
                frame = (MonoInterpFrameHandle*)ext->interp_exit_data;
                ji = mini_get_interp_callbacks ()->frame_get_jit_info (frame);
                if (domain)
                        *domain = mono_domain_get ();
                if (out_ip)
                        *out_ip = mini_get_interp_callbacks ()->frame_get_ip (frame);
        }
        return ji;
}

static void
no_seq_points_found (MonoMethod *method, int offset)
{
        /*
         * This can happen in full-aot mode with assemblies AOTed without the 'soft-debug' option to save space.
         */
        printf ("Unable to find seq points for method '%s', offset 0x%x.\n", mono_method_full_name (method, TRUE), offset);
}

static const char*
ss_depth_to_string (StepDepth depth)
{
        switch (depth) {
        case STEP_DEPTH_OVER:
                return "over";
        case STEP_DEPTH_OUT:
                return "out";
        case STEP_DEPTH_INTO:
                return "into";
        default:
                g_assert_not_reached ();
                return NULL;
        }
}

/*
 * ss_stop:
 *
 *   Stop the single stepping operation given by SS_REQ.
 */
static void
ss_stop (SingleStepReq *ss_req)
{
        if (ss_req->bps) {
                GSList *l;

                for (l = ss_req->bps; l; l = l->next) {
                        mono_de_clear_breakpoint ((MonoBreakpoint *)l->data);
                }
                g_slist_free (ss_req->bps);
                ss_req->bps = NULL;
        }

        ss_req->async_id = 0;
        ss_req->async_stepout_method = NULL;
        if (ss_req->global) {
                mono_de_stop_single_stepping ();
                ss_req->global = FALSE;
        }
}

static void
ss_destroy (SingleStepReq *req)
{
        DEBUG_PRINTF (1, "[dbg] ss_destroy.\n");

        ss_stop (req);

        g_free (req);
}

static SingleStepReq*
ss_req_acquire (void)
{
        SingleStepReq *req;

        dbg_lock ();
        req = the_ss_req;
        if (req)
                req->refcount ++;
        dbg_unlock ();
        return req;
}

static void
mono_de_ss_req_release (SingleStepReq *req)
{
        gboolean free = FALSE;

        dbg_lock ();
        g_assert (req->refcount);
        req->refcount --;
        if (req->refcount == 0)
                free = TRUE;
        dbg_unlock ();
        if (free) {
                if (req == the_ss_req)
                        the_ss_req = NULL;
                ss_destroy (req);
        }
}

void
mono_de_cancel_ss (void)
{
        if (the_ss_req) {
                mono_de_ss_req_release (the_ss_req);
                the_ss_req = NULL;
        }
}


void
mono_de_process_single_step (void *tls, gboolean from_signal)
{
        MonoJitInfo *ji;
        guint8 *ip;
        GPtrArray *reqs;
        int il_offset;
        MonoDomain *domain;
        MonoContext *ctx = rt_callbacks.tls_get_restore_state (tls);
        MonoMethod *method;
        SeqPoint sp;
        MonoSeqPointInfo *info;
        SingleStepReq *ss_req;

        /* Skip the instruction causing the single step */
        rt_callbacks.begin_single_step_processing (ctx, from_signal);

        if (rt_callbacks.try_process_suspend (tls, ctx))
                return;

        /*
         * This can run concurrently with a clear_event_request () call, so needs locking/reference counts.
         */
        ss_req = ss_req_acquire ();

        if (!ss_req)
                // FIXME: A suspend race
                return;

        if (mono_thread_internal_current () != ss_req->thread)
                goto exit;

        ip = (guint8 *)MONO_CONTEXT_GET_IP (ctx);

        ji = get_top_method_ji (ip, &domain, (gpointer*)&ip);
        g_assert (ji && !ji->is_trampoline);

        if (log_level > 0) {
                DEBUG_PRINTF (1, "[%p] Single step event (depth=%s) at %s (%p)[0x%x], sp %p, last sp %p\n", (gpointer) (gsize) mono_native_thread_id_get (), ss_depth_to_string (ss_req->depth), mono_method_full_name (jinfo_get_method (ji), TRUE), MONO_CONTEXT_GET_IP (ctx), (int)((guint8*)MONO_CONTEXT_GET_IP (ctx) - (guint8*)ji->code_start), MONO_CONTEXT_GET_SP (ctx), ss_req->last_sp);
        }

        method = jinfo_get_method (ji);
        g_assert (method);

        if (method->wrapper_type && method->wrapper_type != MONO_WRAPPER_DYNAMIC_METHOD)
                goto exit;

        /* 
         * FIXME:
         * Stopping in memset makes half-initialized vtypes visible.
         * Stopping in memcpy makes half-copied vtypes visible.
         */
        if (method->klass == mono_defaults.string_class && (!strcmp (method->name, "memset") || strstr (method->name, "memcpy")))
                goto exit;

        /*
         * This could be in mono_de_ss_update method, but mono_find_next_seq_point_for_native_offset is pretty expensive method,
         * hence we prefer this check here.
         */
        if (ss_req->user_assemblies) {
                gboolean found = FALSE;
                for (int k = 0; ss_req->user_assemblies[k]; k++)
                        if (ss_req->user_assemblies[k] == m_class_get_image (method->klass)->assembly) {
                                found = TRUE;
                                break;
                        }
                if (!found)
                        goto exit;
        }

        /*
         * The ip points to the instruction causing the single step event, which is before
         * the offset recorded in the seq point map, so find the next seq point after ip.
         */
        if (!mono_find_next_seq_point_for_native_offset (domain, method, (guint8*)ip - (guint8*)ji->code_start, &info, &sp)) {
                g_assert_not_reached ();
                goto exit;
        }

        il_offset = sp.il_offset;

        if (!mono_de_ss_update (ss_req, ji, &sp, tls, ctx, method))
                goto exit;

        /* Start single stepping again from the current sequence point */

        SingleStepArgs args;
        memset (&args, 0, sizeof (args));
        args.method = method;
        args.ctx = ctx;
        args.tls = tls;
        args.step_to_catch = FALSE;
        args.sp = sp;
        args.info = info;
        args.frames = NULL;
        args.nframes = 0;
        mono_de_ss_start (ss_req, &args);

        if ((ss_req->filter & STEP_FILTER_STATIC_CTOR) &&
                (method->flags & METHOD_ATTRIBUTE_SPECIAL_NAME) &&
                !strcmp (method->name, ".cctor"))
                goto exit;

        // FIXME: Has to lock earlier

        reqs = g_ptr_array_new ();

        mono_loader_lock ();

        g_ptr_array_add (reqs, ss_req->req);

        void *bp_events;
        bp_events = rt_callbacks.create_breakpoint_events (reqs, NULL, ji, EVENT_KIND_BREAKPOINT);

        g_ptr_array_free (reqs, TRUE);

        mono_loader_unlock ();

        rt_callbacks.process_breakpoint_events (bp_events, method, ctx, il_offset);

 exit:
        mono_de_ss_req_release (ss_req);
}

/*
 * mono_de_ss_update:
 *
 * Return FALSE if single stepping needs to continue.
 */
static gboolean
mono_de_ss_update (SingleStepReq *req, MonoJitInfo *ji, SeqPoint *sp, void *tls, MonoContext *ctx, MonoMethod* method)
{
        MonoDebugMethodInfo *minfo;
        MonoDebugSourceLocation *loc = NULL;
        gboolean hit = TRUE;

        if ((req->filter & STEP_FILTER_STATIC_CTOR)) {
                DbgEngineStackFrame **frames;
                int nframes;
                rt_callbacks.ss_calculate_framecount (tls, ctx, TRUE, &frames, &nframes);

                gboolean ret = FALSE;
                gboolean method_in_stack = FALSE;

                for (int i = 0; i < nframes; i++) {
                        MonoMethod *external_method = frames [i]->method;
                        if (method == external_method)
                                method_in_stack = TRUE;

                        if (!ret) {
                                ret = (external_method->flags & METHOD_ATTRIBUTE_SPECIAL_NAME);
                                ret = ret && !strcmp (external_method->name, ".cctor");
                                ret = ret && (external_method != req->start_method);
                        }
                }

                if (!method_in_stack) {
                        g_printerr ("[%p] The instruction pointer of the currently executing method(%s) is not on the recorded stack. This is likely due to a runtime bug. The %d frames are as follow: \n", (gpointer)(gsize)mono_native_thread_id_get (), mono_method_full_name (method, TRUE), nframes);
                        /*DEBUG_PRINTF (1, "[%p] The instruction pointer of the currently executing method(%s) is not on the recorded stack. This is likely due to a runtime bug. The %d frames are as follow: \n", (gpointer)(gsize)mono_native_thread_id_get (), mono_method_full_name (method, TRUE), tls->frame_count);*/

                        for (int i=0; i < nframes; i++)
                                g_printerr ("\t [%p] Frame (%d / %d): %s\n", (gpointer)(gsize)mono_native_thread_id_get (), i, nframes, mono_method_full_name (frames [i]->method, TRUE));
                }

                rt_callbacks.ss_discard_frame_context (tls);

                if (ret)
                        return FALSE;
        }

        if (req->async_stepout_method == method) {
                DEBUG_PRINTF (1, "[%p] Breakpoint hit during async step-out at %s hit, continuing stepping out.\n", (gpointer)(gsize)mono_native_thread_id_get (), method->name);
                return FALSE;
        }

        if (req->depth == STEP_DEPTH_OVER && (sp->flags & MONO_SEQ_POINT_FLAG_NONEMPTY_STACK) && !(sp->flags & MONO_SEQ_POINT_FLAG_NESTED_CALL)) {
                /*
                 * These seq points are inserted by the JIT after calls, step over needs to skip them.
                 */
                DEBUG_PRINTF (1, "[%p] Seq point at nonempty stack %x while stepping over, continuing single stepping.\n", (gpointer) (gsize) mono_native_thread_id_get (), sp->il_offset);
                return FALSE;
        }

        if ((req->depth == STEP_DEPTH_OVER || req->depth == STEP_DEPTH_OUT) && hit && !req->async_stepout_method) {
                gboolean is_step_out = req->depth == STEP_DEPTH_OUT;
                int nframes;
                rt_callbacks.ss_calculate_framecount (tls, ctx, FALSE, NULL, &nframes);

                // Because functions can call themselves recursively, we need to make sure we're stopping at the right stack depth.
                // In case of step out, the target is the frame *enclosing* the one where the request was made.
                int target_frames = req->nframes + (is_step_out ? -1 : 0);
                if (req->nframes > 0 && nframes > 0 && nframes > target_frames) {
                        /* Hit the breakpoint in a recursive call, don't halt */
                        DEBUG_PRINTF (1, "[%p] Breakpoint at lower frame while stepping %s, continuing single stepping.\n", (gpointer) (gsize) mono_native_thread_id_get (), is_step_out ? "out" : "over");
                        return FALSE;
                }
        }

        if (req->depth == STEP_DEPTH_INTO && req->size == STEP_SIZE_MIN && (sp->flags & MONO_SEQ_POINT_FLAG_NONEMPTY_STACK) && req->start_method) {
                int nframes;
                rt_callbacks.ss_calculate_framecount (tls, ctx, FALSE, NULL, &nframes);
                if (req->start_method == method && req->nframes && nframes == req->nframes) { //Check also frame count(could be recursion)
                        DEBUG_PRINTF (1, "[%p] Seq point at nonempty stack %x while stepping in, continuing single stepping.\n", (gpointer) (gsize) mono_native_thread_id_get (), sp->il_offset);
                        return FALSE;
                }
        }

        MonoDebugMethodAsyncInfo* async_method = mono_debug_lookup_method_async_debug_info (method);
        if (async_method) {
                for (int i = 0; i < async_method->num_awaits; i++) {
                        if (async_method->yield_offsets[i] == sp->il_offset || async_method->resume_offsets[i] == sp->il_offset) {
                                mono_debug_free_method_async_debug_info (async_method);
                                return FALSE;
                        }
                }
                mono_debug_free_method_async_debug_info (async_method);
        }

        if (req->size != STEP_SIZE_LINE)
                return TRUE;

        /* Have to check whenever a different source line was reached */
        minfo = mono_debug_lookup_method (method);

        if (minfo)
                loc = mono_debug_method_lookup_location (minfo, sp->il_offset);

        if (!loc) {
                DEBUG_PRINTF (1, "[%p] No line number info for il offset %x, continuing single stepping.\n", (gpointer) (gsize) mono_native_thread_id_get (), sp->il_offset);
                req->last_method = method;
                hit = FALSE;
        } else if (loc && method == req->last_method && loc->row == req->last_line) {
                int nframes;
                rt_callbacks.ss_calculate_framecount (tls, ctx, FALSE, NULL, &nframes);
                if (nframes == req->nframes) { // If the frame has changed we're clearly not on the same source line.
                        DEBUG_PRINTF (1, "[%p] Same source line (%d), continuing single stepping.\n", (gpointer) (gsize) mono_native_thread_id_get (), loc->row);
                        hit = FALSE;
                }
        }
                                
        if (loc) {
                req->last_method = method;
                req->last_line = loc->row;
                mono_debug_free_source_location (loc);
        }

        return hit;
}

void
mono_de_process_breakpoint (void *void_tls, gboolean from_signal)
{
        DebuggerTlsData *tls = (DebuggerTlsData*)void_tls;
        MonoJitInfo *ji;
        guint8 *ip;
        int i;
        guint32 native_offset;
        GPtrArray *bp_reqs, *ss_reqs_orig, *ss_reqs;
        EventKind kind = EVENT_KIND_BREAKPOINT;
        MonoContext *ctx = rt_callbacks.tls_get_restore_state (tls);
        MonoMethod *method;
        MonoSeqPointInfo *info;
        SeqPoint sp;
        gboolean found_sp;

        if (rt_callbacks.try_process_suspend (tls, ctx))
                return;

        ip = (guint8 *)MONO_CONTEXT_GET_IP (ctx);

        ji = get_top_method_ji (ip, NULL, (gpointer*)&ip);
        g_assert (ji && !ji->is_trampoline);
        method = jinfo_get_method (ji);

        /* Compute the native offset of the breakpoint from the ip */
        native_offset = ip - (guint8*)ji->code_start;

        if (!rt_callbacks.begin_breakpoint_processing (tls, ctx, ji, from_signal))
                return;

        if (method->wrapper_type)
                return;

        bp_reqs = g_ptr_array_new ();
        ss_reqs = g_ptr_array_new ();
        ss_reqs_orig = g_ptr_array_new ();

        mono_loader_lock ();

        /*
         * The ip points to the instruction causing the breakpoint event, which is after
         * the offset recorded in the seq point map, so find the prev seq point before ip.
         */
        found_sp = mono_find_prev_seq_point_for_native_offset (mono_domain_get (), method, native_offset, &info, &sp);

        if (!found_sp)
                no_seq_points_found (method, native_offset);

        g_assert (found_sp);

        DEBUG_PRINTF (1, "[%p] Breakpoint hit, method=%s, ip=%p, [il=0x%x,native=0x%x].\n", (gpointer) (gsize) mono_native_thread_id_get (), method->name, ip, sp.il_offset, native_offset);

        mono_debugger_log_bp_hit (tls, method, sp.il_offset);

        mono_de_collect_breakpoints_by_sp (&sp, ji, ss_reqs_orig, bp_reqs);

        if (bp_reqs->len == 0 && ss_reqs_orig->len == 0) {
                /* Maybe a method entry/exit event */
                if (sp.il_offset == METHOD_ENTRY_IL_OFFSET)
                        kind = EVENT_KIND_METHOD_ENTRY;
                else if (sp.il_offset == METHOD_EXIT_IL_OFFSET)
                        kind = EVENT_KIND_METHOD_EXIT;
        }

        /* Process single step requests */
        for (i = 0; i < ss_reqs_orig->len; ++i) {
                EventRequest *req = (EventRequest *)g_ptr_array_index (ss_reqs_orig, i);
                SingleStepReq *ss_req = (SingleStepReq *)req->info;
                gboolean hit;

                //if we hit async_stepout_method, it's our no matter which thread
                if ((ss_req->async_stepout_method != method) && (ss_req->async_id || mono_thread_internal_current () != ss_req->thread)) {
                        DbgEngineStackFrame **frames;
                        int nframes;
                        //We have different thread and we don't have async stepping in progress
                        //it's breakpoint in parallel thread, ignore it
                        if (ss_req->async_id == 0)
                                continue;

                        rt_callbacks.ss_discard_frame_context (tls);
                        rt_callbacks.ss_calculate_framecount (tls, ctx, FALSE, &frames, &nframes);
                        //make sure we have enough data to get current async method instance id
                        if (nframes == 0 || !rt_callbacks.ensure_jit (frames [0]))
                                continue;

                        //Check method is async before calling get_this_async_id
                        MonoDebugMethodAsyncInfo* asyncMethod = mono_debug_lookup_method_async_debug_info (method);
                        if (!asyncMethod)
                                continue;
                        else
                                mono_debug_free_method_async_debug_info (asyncMethod);

                        //breakpoint was hit in parallelly executing async method, ignore it
                        if (ss_req->async_id != rt_callbacks.get_this_async_id (frames [0]))
                                continue;
                }

                //Update stepping request to new thread/frame_count that we are continuing on
                //so continuing with normal stepping works as expected
                if (ss_req->async_stepout_method || ss_req->async_id) {
                        int nframes;
                        rt_callbacks.ss_discard_frame_context (tls);
                        rt_callbacks.ss_calculate_framecount (tls, ctx, FALSE, NULL, &nframes);
                        ss_req->thread = mono_thread_internal_current ();
                        ss_req->nframes = nframes;
                }

                hit = mono_de_ss_update (ss_req, ji, &sp, tls, ctx, method);
                if (hit)
                        g_ptr_array_add (ss_reqs, req);

                SingleStepArgs args;
                memset (&args, 0, sizeof (args));
                args.method = method;
                args.ctx = ctx;
                args.tls = tls;
                args.step_to_catch = FALSE;
                args.sp = sp;
                args.info = info;
                args.frames = NULL;
                args.nframes = 0;
                mono_de_ss_start (ss_req, &args);
        }

        void *bp_events = rt_callbacks.create_breakpoint_events (ss_reqs, bp_reqs, ji, kind);

        mono_loader_unlock ();

        g_ptr_array_free (bp_reqs, TRUE);
        g_ptr_array_free (ss_reqs, TRUE);

        rt_callbacks.process_breakpoint_events (bp_events, method, ctx, 0);
}

/*
 * ss_bp_is_unique:
 *
 * Reject breakpoint if it is a duplicate of one already in list or hash table.
 */
static gboolean
ss_bp_is_unique (GSList *bps, GHashTable *ss_req_bp_cache, MonoMethod *method, guint32 il_offset)
{
        if (ss_req_bp_cache) {
                MonoBreakpoint dummy = {method, (long)il_offset, NULL, NULL};
                return !g_hash_table_lookup (ss_req_bp_cache, &dummy);
        }
        for (GSList *l = bps; l; l = l->next) {
                MonoBreakpoint *bp = (MonoBreakpoint *)l->data;
                if (bp->method == method && bp->il_offset == il_offset)
                        return FALSE;
        }
        return TRUE;
}

/*
 * ss_bp_eq:
 *
 * GHashTable equality for a MonoBreakpoint (only care about method and il_offset fields)
 */
static gint
ss_bp_eq (gconstpointer ka, gconstpointer kb)
{
        const MonoBreakpoint *s1 = (const MonoBreakpoint *)ka;
        const MonoBreakpoint *s2 = (const MonoBreakpoint *)kb;
        return (s1->method == s2->method && s1->il_offset == s2->il_offset) ? 1 : 0;
}

/*
 * ss_bp_eq:
 *
 * GHashTable hash for a MonoBreakpoint (only care about method and il_offset fields)
 */
static guint
ss_bp_hash (gconstpointer data)
{
        const MonoBreakpoint *s = (const MonoBreakpoint *)data;
        guint hash = (guint) (uintptr_t) s->method;
        hash ^= ((guint)s->il_offset) << 16; // Assume low bits are more interesting
        hash ^= ((guint)s->il_offset) >> 16;
        return hash;
}

#define MAX_LINEAR_SCAN_BPS 7

/*
 * ss_bp_add_one:
 *
 * Create a new breakpoint and add it to a step request.
 * Will adjust the bp count and cache used by mono_de_ss_start.
 */
static void
ss_bp_add_one (SingleStepReq *ss_req, int *ss_req_bp_count, GHashTable **ss_req_bp_cache,
                  MonoMethod *method, guint32 il_offset)
{
        // This list is getting too long, switch to using the hash table
        if (!*ss_req_bp_cache && *ss_req_bp_count > MAX_LINEAR_SCAN_BPS) {
                *ss_req_bp_cache = g_hash_table_new (ss_bp_hash, ss_bp_eq);
                for (GSList *l = ss_req->bps; l; l = l->next)
                        g_hash_table_insert (*ss_req_bp_cache, l->data, l->data);
        }

        if (ss_bp_is_unique (ss_req->bps, *ss_req_bp_cache, method, il_offset)) {
                // Create and add breakpoint
                MonoBreakpoint *bp = mono_de_set_breakpoint (method, il_offset, ss_req->req, NULL);
                ss_req->bps = g_slist_append (ss_req->bps, bp);
                if (*ss_req_bp_cache)
                        g_hash_table_insert (*ss_req_bp_cache, bp, bp);
                (*ss_req_bp_count)++;
        } else {
                DEBUG_PRINTF (1, "[dbg] Candidate breakpoint at %s:[il=0x%x] is a duplicate for this step request, will not add.\n", mono_method_full_name (method, TRUE), (int)il_offset);
        }
}

static gboolean
is_last_non_empty (SeqPoint* sp, MonoSeqPointInfo *info)
{
        if (!sp->next_len)
                return TRUE;
        SeqPoint* next = g_new (SeqPoint, sp->next_len);
        mono_seq_point_init_next (info, *sp, next);
        for (int i = 0; i < sp->next_len; i++) {
                if (next [i].flags & MONO_SEQ_POINT_FLAG_NONEMPTY_STACK && !(next [i].flags & MONO_SEQ_POINT_FLAG_NESTED_CALL)) {
                        if (!is_last_non_empty (&next [i], info)) {
                                g_free (next);
                                return FALSE;
                        }
                } else {
                        g_free (next);
                        return FALSE;
                }
        }
        g_free (next);
        return TRUE;
}

/*
 * mono_de_ss_start:
 *
 *   Start the single stepping operation given by SS_REQ from the sequence point SP.
 * If CTX is not set, then this can target any thread. If CTX is set, then TLS should
 * belong to the same thread as CTX.
 * If FRAMES is not-null, use that instead of tls->frames for placing breakpoints etc.
 */
static void
mono_de_ss_start (SingleStepReq *ss_req, SingleStepArgs *ss_args)
{
        int i, j, frame_index;
        SeqPoint *next_sp, *parent_sp = NULL;
        SeqPoint local_sp, local_parent_sp;
        gboolean found_sp;
        MonoSeqPointInfo *parent_info;
        MonoMethod *parent_sp_method = NULL;
        gboolean enable_global = FALSE;

        // When 8 or more entries are in bps, we build a hash table to serve as a set of breakpoints.
        // Recreating this on each pass is a little wasteful but at least keeps behavior linear.
        int ss_req_bp_count = g_slist_length (ss_req->bps);
        GHashTable *ss_req_bp_cache = NULL;

        /* Stop the previous operation */
        ss_stop (ss_req);

        gboolean locked = FALSE;

        void *tls = ss_args->tls;
        MonoMethod *method = ss_args->method;
        DbgEngineStackFrame **frames = ss_args->frames;
        int nframes = ss_args->nframes;
        SeqPoint *sp = &ss_args->sp;

        /*
         * Implement single stepping using breakpoints if possible.
         */
        if (ss_args->step_to_catch) {
                ss_bp_add_one (ss_req, &ss_req_bp_count, &ss_req_bp_cache, method, sp->il_offset);
        } else {
                frame_index = 1;

                if (ss_args->ctx && !frames) {

                        mono_loader_lock ();
                        locked = TRUE;

                        /* Need parent frames */
                        rt_callbacks.ss_calculate_framecount (tls, ss_args->ctx, FALSE, &frames, &nframes);
                }

                MonoDebugMethodAsyncInfo* asyncMethod = mono_debug_lookup_method_async_debug_info (method);

                /* Need to stop in catch clauses as well */
                for (i = ss_req->depth == STEP_DEPTH_OUT ? 1 : 0; i < nframes; ++i) {
                        DbgEngineStackFrame *frame = frames [i];

                        if (frame->ji) {
                                MonoJitInfo *jinfo = frame->ji;
                                for (j = 0; j < jinfo->num_clauses; ++j) {
                                        // In case of async method we don't want to place breakpoint on last catch handler(which state machine added for whole method)
                                        if (asyncMethod && asyncMethod->num_awaits && i == 0 && j + 1 == jinfo->num_clauses)
                                                break;
                                        MonoJitExceptionInfo *ei = &jinfo->clauses [j];

                                        if (mono_find_next_seq_point_for_native_offset (frame->domain, frame->method, (char*)ei->handler_start - (char*)jinfo->code_start, NULL, &local_sp))
                                                ss_bp_add_one (ss_req, &ss_req_bp_count, &ss_req_bp_cache, frame->method, local_sp.il_offset);
                                }
                        }
                }

                if (asyncMethod && asyncMethod->num_awaits && nframes && rt_callbacks.ensure_jit (frames [0])) {
                        //asyncMethod has value and num_awaits > 0, this means we are inside async method with awaits

                        // Check if we hit yield_offset during normal stepping, because if we did...
                        // Go into special async stepping mode which places breakpoint on resumeOffset
                        // of this await call and sets async_id so we can distinguish it from parallel executions
                        for (i = 0; i < asyncMethod->num_awaits; i++) {
                                if (sp->il_offset == asyncMethod->yield_offsets [i]) {
                                        ss_req->async_id = rt_callbacks.get_this_async_id (frames [0]);
                                        ss_bp_add_one (ss_req, &ss_req_bp_count, &ss_req_bp_cache, method, asyncMethod->resume_offsets [i]);
                                        g_hash_table_destroy (ss_req_bp_cache);
                                        mono_debug_free_method_async_debug_info (asyncMethod);
                                        if (locked)
                                                mono_loader_unlock ();
                                        goto cleanup;
                                }
                        }
                        //If we are at end of async method and doing step-in or step-over...
                        //Switch to step-out, so whole NotifyDebuggerOfWaitCompletion magic happens...
                        if (is_last_non_empty (sp, ss_args->info)) {
                                ss_req->depth = STEP_DEPTH_OUT;//setting depth to step-out is important, don't inline IF, because code later depends on this
                        }
                        if (ss_req->depth == STEP_DEPTH_OUT) {
                                //If we are inside `async void` method, do normal step-out
                                if (rt_callbacks.set_set_notification_for_wait_completion_flag (frames [0])) {
                                        ss_req->async_id = rt_callbacks.get_this_async_id (frames [0]);
                                        ss_req->async_stepout_method = rt_callbacks.get_notify_debugger_of_wait_completion_method ();
                                        ss_bp_add_one (ss_req, &ss_req_bp_count, &ss_req_bp_cache, ss_req->async_stepout_method, 0);
                                        g_hash_table_destroy (ss_req_bp_cache);
                                        mono_debug_free_method_async_debug_info (asyncMethod);
                                        if (locked)
                                                mono_loader_unlock ();
                                        goto cleanup;
                                }
                        }
                }

                if (asyncMethod)
                        mono_debug_free_method_async_debug_info (asyncMethod);

                /*
                * Find the first sequence point in the current or in a previous frame which
                * is not the last in its method.
                */
                if (ss_req->depth == STEP_DEPTH_OUT) {
                        /* Ignore seq points in current method */
                        while (frame_index < nframes) {
                                DbgEngineStackFrame *frame = frames [frame_index];

                                method = frame->method;
                                found_sp = mono_find_prev_seq_point_for_native_offset (frame->domain, frame->method, frame->native_offset, &ss_args->info, &local_sp);
                                sp = (found_sp)? &local_sp : NULL;
                                frame_index ++;
                                if (sp && sp->next_len != 0)
                                        break;
                        }
                        // There could be method calls before the next seq point in the caller when using nested calls
                        //enable_global = TRUE;
                } else {
                        if (sp && sp->next_len == 0) {
                                sp = NULL;
                                while (frame_index < nframes) {
                                        DbgEngineStackFrame *frame = frames [frame_index];

                                        method = frame->method;
                                        found_sp = mono_find_prev_seq_point_for_native_offset (frame->domain, frame->method, frame->native_offset, &ss_args->info, &local_sp);
                                        sp = (found_sp)? &local_sp : NULL;
                                        if (sp && sp->next_len != 0)
                                                break;
                                        sp = NULL;
                                        frame_index ++;
                                }
                        } else {
                                /* Have to put a breakpoint into a parent frame since the seq points might not cover all control flow out of the method */
                                while (frame_index < nframes) {
                                        DbgEngineStackFrame *frame = frames [frame_index];

                                        parent_sp_method = frame->method;
                                        found_sp = mono_find_prev_seq_point_for_native_offset (frame->domain, frame->method, frame->native_offset, &parent_info, &local_parent_sp);
                                        parent_sp = found_sp ? &local_parent_sp : NULL;
                                        if (found_sp && parent_sp->next_len != 0)
                                                break;
                                        parent_sp = NULL;
                                        frame_index ++;
                                }
                        }
                }

                if (sp && sp->next_len > 0) {
                        SeqPoint* next = g_new(SeqPoint, sp->next_len);

                        mono_seq_point_init_next (ss_args->info, *sp, next);
                        for (i = 0; i < sp->next_len; i++) {
                                next_sp = &next[i];

                                ss_bp_add_one (ss_req, &ss_req_bp_count, &ss_req_bp_cache, method, next_sp->il_offset);
                        }
                        g_free (next);
                }

                if (parent_sp) {
                        SeqPoint* next = g_new(SeqPoint, parent_sp->next_len);

                        mono_seq_point_init_next (parent_info, *parent_sp, next);
                        for (i = 0; i < parent_sp->next_len; i++) {
                                next_sp = &next[i];

                                ss_bp_add_one (ss_req, &ss_req_bp_count, &ss_req_bp_cache, parent_sp_method, next_sp->il_offset);
                        }
                        g_free (next);
                }

                if (ss_req->nframes == 0)
                        ss_req->nframes = nframes;

                if ((ss_req->depth == STEP_DEPTH_OVER) && (!sp && !parent_sp)) {
                        DEBUG_PRINTF (1, "[dbg] No parent frame for step over, transition to step into.\n");
                        /*
                         * This is needed since if we leave managed code, and later return to it, step over
                         * is not going to stop.
                         * This approach is a bit ugly, since we change the step depth, but it only affects
                         * clients who reuse the same step request, and only in this special case.
                         */
                        ss_req->depth = STEP_DEPTH_INTO;
                }

                if (ss_req->depth == STEP_DEPTH_INTO) {
                        /* Enable global stepping so we stop at method entry too */
                        enable_global = TRUE;
                }

                /*
                 * The ctx/frame info computed above will become invalid when we continue.
                 */
                rt_callbacks.ss_discard_frame_context (tls);
        }

        if (enable_global) {
                DEBUG_PRINTF (1, "[dbg] Turning on global single stepping.\n");
                ss_req->global = TRUE;
                mono_de_start_single_stepping ();
        } else if (!ss_req->bps) {
                DEBUG_PRINTF (1, "[dbg] Turning on global single stepping.\n");
                ss_req->global = TRUE;
                mono_de_start_single_stepping ();
        } else {
                ss_req->global = FALSE;
        }

        g_hash_table_destroy (ss_req_bp_cache);

        if (locked)
                mono_loader_unlock ();

cleanup:
        rt_callbacks.ss_args_destroy (ss_args);
}


/*
 * Start single stepping of thread THREAD
 */
DbgEngineErrorCode
mono_de_ss_create (MonoInternalThread *thread, StepSize size, StepDepth depth, StepFilter filter, EventRequest *req)
{
        int err = rt_callbacks.ensure_runtime_is_suspended ();
        if (err)
                return err;

        // FIXME: Multiple requests
        if (the_ss_req) {
                DEBUG_PRINTF (0, "Received a single step request while the previous one was still active.\n");
                return DE_ERR_NOT_IMPLEMENTED;
        }

        DEBUG_PRINTF (1, "[dbg] Starting single step of thread %p (depth=%s).\n", thread, ss_depth_to_string (depth));

        SingleStepReq *ss_req = g_new0 (SingleStepReq, 1);
        ss_req->req = req;
        ss_req->thread = thread;
        ss_req->size = size;
        ss_req->depth = depth;
        ss_req->filter = filter;
        ss_req->refcount = 1;
        req->info = ss_req;

        for (int i = 0; i < req->nmodifiers; i++) {
                if (req->modifiers[i].kind == MOD_KIND_ASSEMBLY_ONLY) {
                        ss_req->user_assemblies = req->modifiers[i].data.assemblies;
                        break;
                }
        }

        SingleStepArgs args;
        err = rt_callbacks.ss_create_init_args (ss_req, &args);
        if (err)
                return err;

        the_ss_req = ss_req;

        mono_de_ss_start (ss_req, &args);

        return DE_ERR_NONE;
}

/*
 * mono_de_set_log_level:
 *
 * Configures logging level and output file. Must be called together with mono_de_init.
 */
void
mono_de_set_log_level (int level, FILE *file)
{
        log_level = level;
        log_file = file;
}

/*
 * mono_de_init:
 *
 * Inits the shared debugger engine. Not reentrant.
 */
void
mono_de_init (DebuggerEngineCallbacks *cbs)
{
        rt_callbacks = *cbs;
        mono_coop_mutex_init_recursive (&debug_mutex);

        domains_init ();
        breakpoints_init ();

        mono_debugger_log_init ();
}

void
mono_de_cleanup (void)
{
        breakpoints_cleanup ();
        domains_cleanup ();
}

void
mono_debugger_free_objref (gpointer value)
{
        ObjRef *o = (ObjRef *)value;

        mono_gchandle_free_internal (o->handle);

        g_free (o);
}
#endif