i#5411 bbdup mem: Shrink per-thread heap usage

clients/drcachesim/tracer/tracer.cpp

@@ -928,6 +928,8 @@ instrumentation_drbbdup_init()
     opts.runtime_case_opnd = OPND_CREATE_ABSMEM(&tracing_disabled, OPSZ_PTR);
     opts.atomic_load_encoding = true;
     opts.non_default_case_limit = 1;
+    // Save per-thread heap for a feature we do not need.
+    opts.never_enable_dynamic_handling = true;
     drbbdup_status_t res = drbbdup_init(&opts);
     DR_ASSERT(res == DRBBDUP_SUCCESS);
     /* We just want barriers and atomic ops: no locks b/c they are not safe. */

ext/drbbdup/drbbdup.c

@@ -127,10 +127,10 @@ typedef struct {
     hashtable_t manager_table; /* Maps bbs with book-keeping data (for thread-private
                                   caches only). */
     int case_index; /* Used to keep track of the current case during insertion. */
-    void *orig_analysis_data;        /* Analysis data accessible for all cases. */
-    void *default_analysis_data;     /* Analysis data specific to default case. */
-    void **case_analysis_data;       /* Analysis data specific to cases. */
-    uint16_t hit_counts[TABLE_SIZE]; /* Keeps track of hit-counts of unhandled cases. */
+    void *orig_analysis_data;      /* Analysis data accessible for all cases. */
+    void *default_analysis_data;   /* Analysis data specific to default case. */
+    void **case_analysis_data;     /* Analysis data specific to cases. */
+    uint16_t *hit_counts;          /* Keeps track of hit-counts of unhandled cases. */
     instr_t *first_instr;          /* The first instr of the bb copy being considered. */
     instr_t *first_nonlabel_instr; /* The first non label instr of the bb copy. */
     instr_t *last_instr;           /* The last instr of the bb copy being considered. */
@@ -324,6 +324,10 @@ drbbdup_create_manager(void *drcontext, void *tag, instrlist_t *bb)
     /* XXX i#3778: To remove once we support specific fragment deletion. */
     DR_ASSERT_MSG(!manager->enable_dynamic_handling,
                   "dynamic case generation is not yet supported");
+    if (opts.never_enable_dynamic_handling) {
+        DR_ASSERT_MSG(!manager->enable_dynamic_handling,
+                      "dynamic case generation was disabled globally: cannot enable");
+    }
 
     /* Check whether user wants copies for this particular bb. */
     if (!manager->enable_dup && manager->cases != NULL) {
@@ -1987,8 +1991,14 @@ drbbdup_get_stats(OUT drbbdup_stats_t *stats_in)
 static void
 drbbdup_thread_init(void *drcontext)
 {
-    drbbdup_per_thread *pt =
-        (drbbdup_per_thread *)dr_thread_alloc(drcontext, sizeof(drbbdup_per_thread));
+    /* We use unreachable heap here too, though with the hit_counts array
+     * dynamically allocated the usage is now small enough to not matter for
+     * most non_default_case_limit values.
+     */
+    drbbdup_per_thread *pt = (drbbdup_per_thread *)dr_custom_alloc(
+        drcontext, DR_ALLOC_THREAD_PRIVATE, sizeof(drbbdup_per_thread),
+        DR_MEMPROT_READ | DR_MEMPROT_WRITE, NULL);
+    memset(pt, 0, sizeof(*pt));
 
     if (is_thread_private) {
         /* Initialise hash table that keeps track of defined cases per
@@ -2001,14 +2011,23 @@ drbbdup_thread_init(void *drcontext)
     pt->case_index = 0;
     pt->orig_analysis_data = NULL;
     ASSERT(opts.non_default_case_limit > 0, "dup limit should be greater than zero");
-    pt->case_analysis_data =
-        dr_thread_alloc(drcontext, sizeof(void *) * opts.non_default_case_limit);
+    pt->case_analysis_data = dr_custom_alloc(drcontext, DR_ALLOC_THREAD_PRIVATE,
+                                             sizeof(void *) * opts.non_default_case_limit,
+                                             DR_MEMPROT_READ | DR_MEMPROT_WRITE, NULL);
     memset(pt->case_analysis_data, 0, sizeof(void *) * opts.non_default_case_limit);
 
-    /* Init hit table. */
-    for (int i = 0; i < TABLE_SIZE; i++)
-        pt->hit_counts[i] = opts.hit_threshold;
-    drbbdup_set_tls_raw_slot_val(DRBBDUP_HIT_TABLE_SLOT, (uintptr_t)pt->hit_counts);
+    if (!opts.never_enable_dynamic_handling) {
+        /* Dynamically allocated to avoid using space when not needed (128K per
+         * thread adds up on large apps), and with explicit unreachable heap.
+         */
+        pt->hit_counts = (uint16_t *)dr_custom_alloc(
+            drcontext, DR_ALLOC_THREAD_PRIVATE, TABLE_SIZE * sizeof(pt->hit_counts[0]),
+            DR_MEMPROT_READ | DR_MEMPROT_WRITE, NULL);
+        /* Init hit table. */
+        for (int i = 0; i < TABLE_SIZE; i++)
+            pt->hit_counts[i] = opts.hit_threshold;
+        drbbdup_set_tls_raw_slot_val(DRBBDUP_HIT_TABLE_SLOT, (uintptr_t)pt->hit_counts);
+    }
 
     drmgr_set_tls_field(drcontext, tls_idx, (void *)pt);
 }
@@ -2024,9 +2043,13 @@ drbbdup_thread_exit(void *drcontext)
     if (is_thread_private)
         hashtable_delete(&pt->manager_table);
 
-    dr_thread_free(drcontext, pt->case_analysis_data,
+    dr_custom_free(drcontext, DR_ALLOC_THREAD_PRIVATE, pt->case_analysis_data,
                    sizeof(void *) * opts.non_default_case_limit);
-    dr_thread_free(drcontext, pt, sizeof(drbbdup_per_thread));
+    if (pt->hit_counts != NULL) {
+        dr_custom_free(drcontext, DR_ALLOC_THREAD_PRIVATE, pt->hit_counts,
+                       TABLE_SIZE * sizeof(pt->hit_counts[0]));
+    }
+    dr_custom_free(drcontext, DR_ALLOC_THREAD_PRIVATE, pt, sizeof(drbbdup_per_thread));
 }
 
 /****************************************************************************

ext/drbbdup/drbbdup.h

@@ -344,6 +344,12 @@ typedef struct {
      * Either this or the instrument_instr field must be set.
      */
     drbbdup_instrument_instr_ex_t instrument_instr_ex;
+    /**
+     * If \p enable_dynamic_handling will *never* be set by \p set_up_bb_dups for
+     * *any* basic block, this field can be set to true.  This reduces memory
+     * usage by not allocating bookkeeping data needed for dynamic handling.
+     */
+    bool never_enable_dynamic_handling;
 } drbbdup_options_t;
 
 /**

suite/tests/client-interface/drbbdup-test.dll.c

@@ -282,6 +282,11 @@ dr_init(client_id_t id)
     opts.user_data = USER_DATA_VAL;
     opts.non_default_case_limit = 2;
     opts.is_stat_enabled = true;
+    /* Test not triggering lazy allocation paths.
+     * Since subsequent enabling for a block results in an assert rather than a failure
+     * return code or something we can't easily test that.
+     */
+    opts.never_enable_dynamic_handling = true;
 
     drbbdup_status_t res = drbbdup_init(&opts);
     CHECK(res == DRBBDUP_SUCCESS, "drbbdup init failed");