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new macros 'likely'/'unlikely' with hints for jump predictions

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(used only in errors for now)
This commit is contained in:
Roberto Ierusalimschy
2018-05-30 11:25:52 -03:00
parent 97e394ba18
commit 34aa0c5bd7
6 changed files with 78 additions and 48 deletions
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44
lmem.c
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@@ -1,5 +1,5 @@
/*
** $Id: lmem.c,v 1.95 2017/12/11 12:27:48 roberto Exp roberto $
** $Id: lmem.c,v 1.96 2018/01/28 15:13:26 roberto Exp roberto $
** Interface to Memory Manager
** See Copyright Notice in lua.h
*/
@@ -60,7 +60,7 @@ void *luaM_growaux_ (lua_State *L, void *block, int nelems, int *psize,
if (nelems + 1 <= size) /* does one extra element still fit? */
return block; /* nothing to be done */
if (size >= limit / 2) { /* cannot double it? */
if (size >= limit) /* cannot grow even a little? */
if (unlikely(size >= limit)) /* cannot grow even a little? */
luaG_runerror(L, "too many %s (limit is %d)", what, limit);
size = limit; /* still have at least one free place */
}
@@ -73,7 +73,7 @@ void *luaM_growaux_ (lua_State *L, void *block, int nelems, int *psize,
/* 'limit' ensures that multiplication will not overflow */
newblock = luaM_realloc_(L, block, cast_sizet(*psize) * size_elems,
cast_sizet(size) * size_elems);
if (newblock == NULL)
if (unlikely(newblock == NULL))
luaM_error(L);
*psize = size; /* update only when everything else is OK */
return newblock;
@@ -88,7 +88,7 @@ void *luaM_shrinkvector_ (lua_State *L, void *block, int *size,
size_t newsize = cast_sizet(final_n * size_elem);
lua_assert(newsize <= oldsize);
newblock = (*g->frealloc)(g->ud, block, oldsize, newsize);
if (newblock == NULL && final_n > 0) /* allocation failed? */
if (unlikely(newblock == NULL && final_n > 0)) /* allocation failed? */
luaM_error(L);
else {
g->GCdebt += newsize - oldsize;
@@ -114,6 +114,22 @@ void luaM_free_ (lua_State *L, void *block, size_t osize) {
}
/*
** In case of allocation fail, this function will call the GC to try
** to free some memory and then try the allocation again.
** (It should not be called when shrinking a block, because then the
** interpreter may be in the middle of a collection step.)
*/
static void *tryagain (lua_State *L, void *block,
size_t osize, size_t nsize) {
global_State *g = G(L);
if (g->version) { /* is state fully build? */
luaC_fullgc(L, 1); /* try to free some memory... */
return (*g->frealloc)(g->ud, block, osize, nsize); /* try again */
}
else return NULL; /* cannot free any memory without a full state */
}
/*
** generic allocation routine.
@@ -124,13 +140,10 @@ void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
lua_assert((osize == 0) == (block == NULL));
hardtest(L, osize, nsize);
newblock = (*g->frealloc)(g->ud, block, osize, nsize);
if (newblock == NULL && nsize > 0) {
/* Is state fully built? Not shrinking a block? */
if (g->version && nsize > osize) {
luaC_fullgc(L, 1); /* try to free some memory... */
newblock = (*g->frealloc)(g->ud, block, osize, nsize); /* try again */
}
if (newblock == NULL)
if (unlikely(newblock == NULL && nsize > 0)) {
if (nsize > osize) /* not shrinking a block? */
newblock = tryagain(L, block, osize, nsize);
if (newblock == NULL) /* still no memory? */
return NULL;
}
lua_assert((nsize == 0) == (newblock == NULL));
@@ -142,7 +155,7 @@ void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
void *luaM_saferealloc_ (lua_State *L, void *block, size_t osize,
size_t nsize) {
void *newblock = luaM_realloc_(L, block, osize, nsize);
if (newblock == NULL && nsize > 0) /* allocation failed? */
if (unlikely(newblock == NULL && nsize > 0)) /* allocation failed? */
luaM_error(L);
return newblock;
}
@@ -155,11 +168,8 @@ void *luaM_malloc_ (lua_State *L, size_t size, int tag) {
else {
global_State *g = G(L);
void *newblock = (*g->frealloc)(g->ud, NULL, tag, size);
if (newblock == NULL) {
if (g->version) { /* is state fully built? */
luaC_fullgc(L, 1); /* try to free some memory... */
newblock = (*g->frealloc)(g->ud, NULL, tag, size); /* try again */
}
if (unlikely(newblock == NULL)) {
newblock = tryagain(L, NULL, tag, size);
if (newblock == NULL)
luaM_error(L);
}