From 19ba70e988f7766b529731bc88005a079f68409e Mon Sep 17 00:00:00 2001
From: Richard Frith-MacDonald <rfm@gnu.org>
Date: Fri, 22 May 2015 16:24:27 +0000
Subject: [PATCH] Another tiny string optimisation

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@38525 72102866-910b-0410-8b05-ffd578937521
---
 Source/GSString.m | 48 +++++++++++++++++++++++++++++++++++++++++++++++
 Source/NSString.m | 13 ++++++++++---
 2 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/Source/GSString.m b/Source/GSString.m
index 2d7c41483..0caab5a1c 100644
--- a/Source/GSString.m
+++ b/Source/GSString.m
@@ -749,6 +749,38 @@ static BOOL useTinyStrings;
 #define TINY_STRING_CHAR(s, x) ((s & (0xFE00000000000000 >> (x*7))) >> (57-(x*7)))
 #define TINY_STRING_LENGTH_MASK 0x1f
 #define TINY_STRING_LENGTH_SHIFT OBJC_SMALL_OBJECT_SHIFT
+
+static BOOL
+tinyEqualToString(uintptr_t s, NSString *aString)
+{
+  NSUInteger    l;
+
+  if ((NSString*)s == aString)
+    {
+      return YES;
+    }
+  
+  l = (s >> TINY_STRING_LENGTH_SHIFT) & TINY_STRING_LENGTH_MASK;
+  if ([aString length] != l)
+    {
+      return NO;
+    }
+  else if (l > 0)
+    {
+      unichar   buf[8];
+
+      [aString getCharacters: buf range: NSMakeRange(0, l)];
+      while (l-- > 0)
+        {
+          if ((unichar)TINY_STRING_CHAR(s, l) != buf[l])
+            {
+              return NO;
+            }
+        }
+    }
+  return YES;
+}
+
 @interface GSTinyString : NSString
 @end
 
@@ -950,6 +982,11 @@ tsbytes(uintptr_t s, char *buf)
 #endif
 }
 
+- (BOOL) isEqualToString: (NSString*)aString
+{
+  return tinyEqualToString((uintptr_t)self, aString);
+}
+
 - (NSUInteger) length
 {
   uintptr_t s = (uintptr_t)self;
@@ -5571,6 +5608,17 @@ literalIsEqual(NXConstantString *self, id anObject)
     {
       return NO;
     }
+#if defined(OBJC_SMALL_OBJECT_SHIFT) && (OBJC_SMALL_OBJECT_SHIFT == 3)
+  if (useTinyStrings)
+    {
+      uintptr_t s = (uintptr_t)anObject;
+
+      if (s & TINY_STRING_MASK)
+        {
+          return tinyEqualToString((uintptr_t)anObject, self);
+        }
+    }
+#endif
   if (GSObjCIsInstance(anObject) == NO)
     {
       return NO;
diff --git a/Source/NSString.m b/Source/NSString.m
index 77c638601..e7634606d 100644
--- a/Source/NSString.m
+++ b/Source/NSString.m
@@ -2685,12 +2685,19 @@ static BOOL             (*nbImp)(id, SEL, unichar) = 0;
  */
 - (BOOL) isEqualToString: (NSString*)aString
 {
+  if (aString == self)
+    {
+      return YES;
+    }
   if ([self hash] != [aString hash])
-    return NO;
-
+    {
+      return NO;
+    }
   if (strCompNsNs(self, aString, 0, (NSRange){0, [self length]})
     == NSOrderedSame)
-    return YES;
+    {
+      return YES;
+    }
   return NO;
 }