More tweaks to use less stack space

Author: rfm

Source/GSPrivate.h

@@ -107,35 +107,37 @@ __attribute__((unused)) static void GSFreeTempBuffer(void **b)
   if (NULL != *b) free(*b);
 }
 #  define	GS_BEGINITEMBUF(P, S, T) { \
-  T _ibuf[GS_MAX_OBJECTS_FROM_STACK];\
+  unsigned _ilen = (S) > 0 ? (S) : 1; \
+  T _ibuf[_ilen <= GS_MAX_OBJECTS_FROM_STACK ? _ilen : 1]; \
   T *P = _ibuf;\
   __attribute__((cleanup(GSFreeTempBuffer))) void *_base = 0;\
-  if (S > GS_MAX_OBJECTS_FROM_STACK)\
+  if (_ilen > GS_MAX_OBJECTS_FROM_STACK)\
     {\
-      _base = malloc((S) * sizeof(T));\
+      _base = malloc(_ilen * sizeof(T));\
       P = _base;\
     }
 #  define	GS_BEGINITEMBUF2(P, S, T) { \
-  T _ibuf2[GS_MAX_OBJECTS_FROM_STACK];\
+  unsigned _ilen2 = (S) > 0 ? (S) : 1; \
+  T _ibuf2[_ilen2 <= GS_MAX_OBJECTS_FROM_STACK ? _ilen2 : 1]; \
   T *P = _ibuf2;\
   __attribute__((cleanup(GSFreeTempBuffer))) void *_base2 = 0;\
-  if (S > GS_MAX_OBJECTS_FROM_STACK)\
+  if (_ilen2 > GS_MAX_OBJECTS_FROM_STACK)\
     {\
-      _base2 = malloc((S) * sizeof(T));\
+      _base2 = malloc(_ilen2 * sizeof(T));\
       P = _base2;\
     }
 #else
-/* Make minimum size of _ibuf 1 to avoid compiler warnings.
- */
 #  define	GS_BEGINITEMBUF(P, S, T) { \
-  T _ibuf[(S) > 0 && (S) <= GS_MAX_OBJECTS_FROM_STACK ? (S) : 1]; \
-  T *_base = ((S) <= GS_MAX_OBJECTS_FROM_STACK) ? _ibuf \
-    : (T*)malloc((S) * sizeof(T)); \
+  unsigned _ilen = (S) > 0 ? (S) : 1; \
+  T _ibuf[_ilen <= GS_MAX_OBJECTS_FROM_STACK ? _ilen : 1]; \
+  T *_base = (_ilen <= GS_MAX_OBJECTS_FROM_STACK) ? _ibuf \
+    : (T*)malloc(_ilen * sizeof(T)); \
   T *(P) = _base;
 #  define	GS_BEGINITEMBUF2(P, S, T) { \
-  T _ibuf2[(S) > 0 && (S) <= GS_MAX_OBJECTS_FROM_STACK ? (S) : 1]; \
-  T *_base2 = ((S) <= GS_MAX_OBJECTS_FROM_STACK) ? _ibuf2 \
-    : (T*)malloc((S) * sizeof(T)); \
+  unsigned _ilen2 = (S) > 0 ? (S) : 1; \
+  T _ibuf2[_ilen2 <= GS_MAX_OBJECTS_FROM_STACK ? _ilen2 : 1]; \
+  T *_base2 = (_ilen2 <= GS_MAX_OBJECTS_FROM_STACK) ? _ibuf2 \
+    : (T*)malloc(_ilen2 * sizeof(T)); \
   T *(P) = _base2;
 #endif
 

Source/NSString.m

@@ -5974,37 +5974,18 @@ - (NSComparisonResult) compare: (NSString *)string
 	{
 	  NSUInteger		countSelf = compareRange.length;
 	  NSUInteger		countOther = [string length];       
-	  unichar		*charsSelf;
-	  unichar		*charsOther;
 	  UCollationResult	result;
-	  NSUInteger 		sizeSelf = countSelf * sizeof(unichar);
-	  NSUInteger 		sizeOther = countOther * sizeof(unichar);
-	  BOOL			useStack = (sizeSelf + sizeOther) < 128;
-
-	  if (useStack)
-	    {
-	      charsSelf = alloca(sizeSelf ? sizeSelf : 1);
-	      charsOther = alloca(sizeOther ? sizeOther : 1);
-	    }
-	  else
-	    {
-	      charsSelf = malloc(sizeSelf ? sizeSelf : 1);
-	      charsOther = malloc(sizeOther ? sizeOther : 1);
-	    }
+          GS_BEGINITEMBUF(chars, countOther + countSelf, unichar)
 
 	  // Copy to buffer
-	  [self getCharacters: charsSelf range: compareRange];
-	  [string getCharacters: charsOther range: NSMakeRange(0, countOther)];
+	  [self getCharacters: chars range: compareRange];
+	  [string getCharacters: chars + countSelf
+			  range: NSMakeRange(0, countOther)];
 
 	  result = ucol_strcoll(coll,
-	    charsSelf, countSelf, charsOther, countOther);
+	    chars, countSelf, chars + countSelf, countOther);
+          GS_ENDITEMBUF()
 
-	  if (!useStack)
-	    {
-	      free(charsSelf);
-	      free(charsOther);	  
-	    }
-	  
 	  /* UCollationResult enums are stable and match
 	   * NSComparisonResult enums
 	   */