point2uint for blua interning string cache

src/blua/llimits.h

@@ -41,6 +41,25 @@ typedef unsigned char lu_byte;
 */
 #define IntPoint(p)  ((unsigned int)(lu_mem)(p))
 
+/*
+** conversion of pointer to unsigned integer: this is for hashing only;
+** there is no problem if the integer cannot hold the whole pointer
+** value. (In strict ISO C this may cause undefined behavior, but no
+** actual machine seems to bother.)
+*/
+#if !defined(LUA_USE_C89) && defined(__STDC_VERSION__) && \
+    __STDC_VERSION__ >= 199901L
+#include <stdint.h>
+#if defined(UINTPTR_MAX)  /* even in C99 this type is optional */
+#define L_P2I	uintptr_t
+#else  /* no 'intptr'? */
+#define L_P2I	uintmax_t  /* use the largest available integer */
+#endif
+#else  /* C89 option */
+#define L_P2I	size_t
+#endif
+
+#define point2uint(p)	((unsigned int)((L_P2I)(p) & UINT_MAX))
 
 
 /* type to ensure maximum alignment */

src/blua/lstring.c

@@ -191,7 +191,7 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
 ** check hits.
 */
 TString *luaS_new (lua_State *L, const char *str) {
-  unsigned int i = IntPoint(str) % STRCACHE_N;  /* hash */
+  unsigned int i = point2uint(str) % STRCACHE_N;  /* hash */
   int j;
   TString **p = G(L)->strcache[i];
   for (j = 0; j < STRCACHE_M; j++) {