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perf(callgrind): FNV-1a hash + stored-hash pre-filter in name lookups #27

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perf(callgrind): FNV-1a hash + stored-hash pre-filter in name lookups #27

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68 changes: 45 additions & 23 deletions callgrind/fn.c
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Original file line number Diff line number Diff line change
Expand Up @@ -307,21 +307,31 @@ void CLG_(init_obj_table)(void)
obj_table[i] = 0;
}

#define HASH_CONSTANT 256

static UInt str_hash(const HChar *s, UInt table_size)
#define FNV_OFFSET_BASIS 2166136261u
#define FNV_PRIME 16777619u

/* Compute a full 32-bit FNV-1a hash of a string.
* FNV-1a provides excellent distribution, much better than the
* original shift-by-8 hash which only considered the last 4 bytes
* of each string. The improved distribution reduces chain lengths
* in the hash tables and eliminates most strcmp calls when combined
* with the stored-hash comparison in lookup functions.
*/
static UInt str_hash_full(const HChar *s)
{
int hash_value = 0;
for ( ; *s; s++)
hash_value = (HASH_CONSTANT * hash_value + *s) % table_size;
return hash_value;
UInt hash = FNV_OFFSET_BASIS;
for ( ; *s; s++) {
hash ^= (UChar)*s;
hash *= FNV_PRIME;
}
return hash;
}


static const HChar* anonymous_obj = "???";

static __inline__
obj_node* new_obj_node(DebugInfo* di, obj_node* next)
obj_node* new_obj_node(DebugInfo* di, UInt objname_full_hash,
obj_node* next)
{
Int i;
obj_node* obj;
Expand All @@ -330,6 +340,7 @@ obj_node* new_obj_node(DebugInfo* di, obj_node* next)
obj->name = di ? VG_(strdup)( "cl.fn.non.2",
VG_(DebugInfo_get_filename)(di) )
: anonymous_obj;
obj->name_hash = objname_full_hash;
for (i = 0; i < N_FILE_ENTRIES; i++) {
obj->files[i] = NULL;
}
Expand Down Expand Up @@ -359,35 +370,39 @@ obj_node* new_obj_node(DebugInfo* di, obj_node* next)
obj_node* CLG_(get_obj_node)(DebugInfo* di)
{
obj_node* curr_obj_node;
UInt objname_full_hash;
UInt objname_hash;
const HChar* obj_name;

obj_name = di ? VG_(DebugInfo_get_filename)(di) : anonymous_obj;

/* lookup in obj hash */
objname_hash = str_hash(obj_name, N_OBJ_ENTRIES);
objname_full_hash = str_hash_full(obj_name);
objname_hash = objname_full_hash % N_OBJ_ENTRIES;
curr_obj_node = obj_table[objname_hash];
while (NULL != curr_obj_node &&
VG_(strcmp)(obj_name, curr_obj_node->name) != 0) {
while (NULL != curr_obj_node &&
(curr_obj_node->name_hash != objname_full_hash ||
VG_(strcmp)(obj_name, curr_obj_node->name) != 0)) {
curr_obj_node = curr_obj_node->next;
}
if (NULL == curr_obj_node) {
obj_table[objname_hash] = curr_obj_node =
new_obj_node(di, obj_table[objname_hash]);
new_obj_node(di, objname_full_hash, obj_table[objname_hash]);
}

return curr_obj_node;
}


static __inline__
file_node* new_file_node(const HChar *filename,
file_node* new_file_node(const HChar *filename, UInt filename_full_hash,
obj_node* obj, file_node* next)
{
Int i;
file_node* file = (file_node*) CLG_MALLOC("cl.fn.nfn.1",
sizeof(file_node));
file->name = VG_(strdup)("cl.fn.nfn.2", filename);
file->name_hash = filename_full_hash;
for (i = 0; i < N_FN_ENTRIES; i++) {
file->fns[i] = NULL;
}
Expand All @@ -403,6 +418,7 @@ file_node* CLG_(get_file_node)(obj_node* curr_obj_node,
const HChar *dir, const HChar *file)
{
file_node* curr_file_node;
UInt filename_full_hash;
UInt filename_hash;

/* Build up an absolute pathname, if there is a directory available */
Expand All @@ -414,15 +430,17 @@ file_node* CLG_(get_file_node)(obj_node* curr_obj_node,
VG_(strcat)(filename, file);

/* lookup in file hash */
filename_hash = str_hash(filename, N_FILE_ENTRIES);
filename_full_hash = str_hash_full(filename);
filename_hash = filename_full_hash % N_FILE_ENTRIES;
curr_file_node = curr_obj_node->files[filename_hash];
while (NULL != curr_file_node &&
VG_(strcmp)(filename, curr_file_node->name) != 0) {
while (NULL != curr_file_node &&
(curr_file_node->name_hash != filename_full_hash ||
VG_(strcmp)(filename, curr_file_node->name) != 0)) {
curr_file_node = curr_file_node->next;
}
if (NULL == curr_file_node) {
curr_obj_node->files[filename_hash] = curr_file_node =
new_file_node(filename, curr_obj_node,
new_file_node(filename, filename_full_hash, curr_obj_node,
curr_obj_node->files[filename_hash]);
}

Expand All @@ -433,12 +451,13 @@ file_node* CLG_(get_file_node)(obj_node* curr_obj_node,
static void resize_fn_array(void);

static __inline__
fn_node* new_fn_node(const HChar *fnname,
fn_node* new_fn_node(const HChar *fnname, UInt fnname_full_hash,
file_node* file, fn_node* next)
{
fn_node* fn = (fn_node*) CLG_MALLOC("cl.fn.nfnnd.1",
sizeof(fn_node));
fn->name = VG_(strdup)("cl.fn.nfnnd.2", fnname);
fn->name_hash = fnname_full_hash;

CLG_(stat).distinct_fns++;
fn->number = CLG_(stat).distinct_fns;
Expand Down Expand Up @@ -481,20 +500,23 @@ fn_node* get_fn_node_infile(file_node* curr_file_node,
const HChar *fnname)
{
fn_node* curr_fn_node;
UInt fnname_full_hash;
UInt fnname_hash;

CLG_ASSERT(curr_file_node != 0);

/* lookup in function hash */
fnname_hash = str_hash(fnname, N_FN_ENTRIES);
fnname_full_hash = str_hash_full(fnname);
fnname_hash = fnname_full_hash % N_FN_ENTRIES;
curr_fn_node = curr_file_node->fns[fnname_hash];
while (NULL != curr_fn_node &&
VG_(strcmp)(fnname, curr_fn_node->name) != 0) {
while (NULL != curr_fn_node &&
(curr_fn_node->name_hash != fnname_full_hash ||
VG_(strcmp)(fnname, curr_fn_node->name) != 0)) {
curr_fn_node = curr_fn_node->next;
}
if (NULL == curr_fn_node) {
curr_file_node->fns[fnname_hash] = curr_fn_node =
new_fn_node(fnname, curr_file_node,
new_fn_node(fnname, fnname_full_hash, curr_file_node,
curr_file_node->fns[fnname_hash]);
}

Expand Down
3 changes: 3 additions & 0 deletions callgrind/global.h
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Original file line number Diff line number Diff line change
Expand Up @@ -408,6 +408,7 @@ struct _BBCC {

struct _fn_node {
HChar* name;
UInt name_hash; /* full 32-bit hash for fast lookup */
UInt number;
Context* last_cxt; /* LRU info */
Context* pure_cxt; /* the context with only the function itself */
Expand Down Expand Up @@ -442,6 +443,7 @@ struct _fn_node {

struct _file_node {
HChar* name;
UInt name_hash; /* full 32-bit hash for fast lookup */
fn_node* fns[N_FN_ENTRIES];
UInt number;
obj_node* obj;
Expand All @@ -454,6 +456,7 @@ struct _file_node {
*/
struct _obj_node {
const HChar* name;
UInt name_hash; /* full 32-bit hash for fast lookup */
UInt last_slash_pos;

Addr start; /* Start address of text segment mapping */
Expand Down
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