average_bb_size.p3

Next we add code to track the size of blocks as we build them for our as-built count. This will give us the number of blocks built and their average size. Next we will add the dynamic execution counts.

#include "dr_api.h"

+ #ifdef WINDOWS
+ # define DISPLAY_STRING(msg) dr_messagebox(msg)
+ #else
+ # define DISPLAY_STRING(msg) dr_printf("%s\n", msg)
+ #endif

+ typedef struct bb_counts {
+    uint64 blocks;
+    uint64 total_size;
+ } bb_counts;

+ static bb_counts counts_as_built;
+ void *as_built_lock;

static void
event_exit(void);
static dr_emit_flags_t
event_basic_block(void *drcontext, void *tag, instrlist_t *bb,
                  bool for_trace, bool translating);

DR_EXPORT void
dr_client_main(client_id_t id, int argc, const char *argv[])
{
    /* register events */
    dr_register_exit_event(event_exit);
    dr_register_bb_event(event_basic_block);
+
+     /* initialize lock */
+     as_built_lock = dr_mutex_create();
}

static void
event_exit(void)
{
+     /* Display results - we must first snpritnf the string as on windows
+      * dr_printf(), dr_messagebox() and dr_fprintf() can't print floats. */
+     char msg[512];
+     int len;
+     len = snprintf(msg, sizeof(msg)/sizeof(msg[0]),
+                    "Number of basic blocks built : %"UINT64_FORMAT_CODE"\n"
+                    "     Average size            : %5.2lf instructions\n",
+                    counts_as_built.blocks,
+                    counts_as_built.total_size / (double)counts_as_built.blocks);
+     DR_ASSERT(len > 0);
+     msg[sizeof(msg)/sizeof(msg[0])-1] = '\0'; /* NUll terminate */
+     DISPLAY_STRING(msg);
+
+      /* free mutex */
+      dr_mutex_destroy(as_built_lock);
}

static dr_emit_flags_t
event_basic_block(void *drcontext, void *tag, instrlist_t *bb,
                  bool for_trace, bool translating)
{
+     uint num_instructions = 0;
+     instr_t *instr;
+
+     /* count the number of instructions in this block */
+     for (instr = instrlist_first(bb); instr != NULL; instr = instr_get_next(instr)) {
+         num_instructions++;
+     }
+
+     /* update the as-built counts */
+     dr_mutex_lock(as_built_lock);
+     counts_as_built.blocks++;
+     counts_as_built.total_size += num_instructions;
+     dr_mutex_unlock(as_built_lock);
    return DR_EMIT_DEFAULT;
}

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