Performance enhancements and size reduction for sqlite3VXPrintf()

FossilOrigin-Name: eb071eb58cf675bd6cd9dd46aed9d57fbb7a77e8

manifest

@@ -1,5 +1,5 @@
-C Fix\sa\sharmless\scompiler\swarning\sthat\scrops\sup\swith\sSQLITE_MAX_MMAP_SIZE=0.
-D 2014-03-14T11:46:10.508
+C Performance\senhancements\sand\ssize\sreduction\sfor\ssqlite3VXPrintf()
+D 2014-03-17T14:24:27.523
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -213,7 +213,7 @@ F src/pcache.h a5e4f5d9f5d592051d91212c5949517971ae6222
 F src/pcache1.c 102e6f5a2fbc646154463eb856d1fd716867b64c
 F src/pragma.c e78b4bf2a267de2c17ee09f90b6807cf8d40e6a3
 F src/prepare.c 677521ab7132615a8a26107a1d1c3132f44ae337
-F src/printf.c 85d07756e45d7496d19439dcae3e6e9e0090f269
+F src/printf.c d95ea1b8a1e825a2f4756322f2ce35f91289fa1a
 F src/random.c d10c1f85b6709ca97278428fd5db5bbb9c74eece
 F src/resolve.c 273d5f47c4e2c05b2d3d2bffeda939551ab59e66
 F src/rowset.c 64655f1a627c9c212d9ab497899e7424a34222e0
@@ -1156,7 +1156,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P 6504aa47a8ebb13827be017c4cb4b2dc3c4c55f4
-R afd560ffe96625fe4d1d6971544be730
+P 1277932b7e8bb36c7070ffafbf110a8e128c267b
+R 6d92934790c660d014aba176737edbd6
 U drh
-Z 413087b4f5e9f622f8abe560a87a95ed
+Z c25cfd9c876d8aae4bc2be28c38a9b40

manifest.uuid

@@ -1 +1 @@
-1277932b7e8bb36c7070ffafbf110a8e128c267b
+eb071eb58cf675bd6cd9dd46aed9d57fbb7a77e8

src/printf.c

@@ -134,20 +134,6 @@ static char et_getdigit(LONGDOUBLE_TYPE *val, int *cnt){
 }
 #endif /* SQLITE_OMIT_FLOATING_POINT */
 
-/*
-** Append N space characters to the given string buffer.
-*/
-void sqlite3AppendSpace(StrAccum *pAccum, int N){
-  static const char zSpaces[] = "                             ";
-  while( N>=(int)sizeof(zSpaces)-1 ){
-    sqlite3StrAccumAppend(pAccum, zSpaces, sizeof(zSpaces)-1);
-    N -= sizeof(zSpaces)-1;
-  }
-  if( N>0 ){
-    sqlite3StrAccumAppend(pAccum, zSpaces, N);
-  }
-}
-
 /*
 ** Set the StrAccum object to an error mode.
 */
@@ -237,11 +223,9 @@ void sqlite3VXPrintf(
   }
   for(; (c=(*fmt))!=0; ++fmt){
     if( c!='%' ){
-      int amt;
       bufpt = (char *)fmt;
-      amt = 1;
-      while( (c=(*++fmt))!='%' && c!=0 ) amt++;
-      sqlite3StrAccumAppend(pAccum, bufpt, amt);
+      while( (c=(*++fmt))!='%' && c!=0 ){};
+      sqlite3StrAccumAppend(pAccum, bufpt, (int)(fmt - bufpt));
       if( c==0 ) break;
     }
     if( (c=(*++fmt))==0 ){
@@ -729,48 +713,34 @@ void sqlite3VXPrintf(
     ** "length" characters long.  The field width is "width".  Do
     ** the output.
     */
-    if( !flag_leftjustify ){
-      register int nspace;
-      nspace = width-length;
-      if( nspace>0 ){
-        sqlite3AppendSpace(pAccum, nspace);
-      }
-    }
-    if( length>0 ){
+    width -= length;
+    if( width>0 && !flag_leftjustify ) sqlite3AppendSpace(pAccum, width);
     sqlite3StrAccumAppend(pAccum, bufpt, length);
-    }
-    if( flag_leftjustify ){
-      register int nspace;
-      nspace = width-length;
-      if( nspace>0 ){
-        sqlite3AppendSpace(pAccum, nspace);
-      }
-    }
+    if( width>0 && flag_leftjustify ) sqlite3AppendSpace(pAccum, width);
+
     if( zExtra ) sqlite3_free(zExtra);
   }/* End for loop over the format string */
 } /* End of function */
 
 /*
-** Append N bytes of text from z to the StrAccum object.
+** Enlarge the memory allocation on a StrAccum object so that it is
+** able to accept at least N more bytes of text.
+**
+** Return the number of bytes of text that StrAccum is able to accept
+** after the attempted enlargement.  The value returned might be zero.
 */
-void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
-  assert( z!=0 );
-  assert( p->zText!=0 || p->nChar==0 || p->accError );
-  assert( N>=0 );
-  assert( p->accError==0 || p->nAlloc==0 );
-  if( p->nChar+N >= p->nAlloc ){
+static int sqlite3StrAccumEnlarge(StrAccum *p, int N){
   char *zNew;
+  assert( p->nChar+N >= p->nAlloc ); /* Only called if really needed */
   if( p->accError ){
     testcase(p->accError==STRACCUM_TOOBIG);
     testcase(p->accError==STRACCUM_NOMEM);
-      return;
+    return 0;
   }
   if( !p->useMalloc ){
     N = p->nAlloc - p->nChar - 1;
     setStrAccumError(p, STRACCUM_TOOBIG);
-      if( N<=0 ){
-        return;
-      }
+    return N;
   }else{
     char *zOld = (p->zText==p->zBase ? 0 : p->zText);
     i64 szNew = p->nChar;
@@ -778,7 +748,7 @@ void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
     if( szNew > p->mxAlloc ){
       sqlite3StrAccumReset(p);
       setStrAccumError(p, STRACCUM_TOOBIG);
-        return;
+      return 0;
     }else{
       p->nAlloc = (int)szNew;
     }
@@ -793,10 +763,49 @@ void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
     }else{
       sqlite3StrAccumReset(p);
       setStrAccumError(p, STRACCUM_NOMEM);
+      return 0;
+    }
+  }
+  return N;
+}
+
+/*
+** Append N space characters to the given string buffer.
+*/
+void sqlite3AppendSpace(StrAccum *p, int N){
+  if( p->nChar+N >= p->nAlloc && (N = sqlite3StrAccumEnlarge(p, N))<=0 ) return;
+  while( (N--)>0 ) p->zText[p->nChar++] = ' ';
+}
+
+/*
+** The StrAccum "p" is not large enough to accept N new bytes of z[].
+** So enlarge if first, then do the append.
+**
+** This is a helper routine to sqlite3StrAccumAppend() that does special-case
+** work (enlarging the buffer) using tail recursion, so that the
+** sqlite3StrAccumAppend() routine can use fast calling semantics.
+*/
+static void enlargeAndAppend(StrAccum *p, const char *z, int N){
+  N = sqlite3StrAccumEnlarge(p, N);
+  if( N>0 ){
+    memcpy(&p->zText[p->nChar], z, N);
+    p->nChar += N;
+  }
+}
+
+/*
+** Append N bytes of text from z to the StrAccum object.  Increase the
+** size of the memory allocation for StrAccum if necessary.
+*/
+void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
+  assert( z!=0 );
+  assert( p->zText!=0 || p->nChar==0 || p->accError );
+  assert( N>=0 );
+  assert( p->accError==0 || p->nAlloc==0 );
+  if( p->nChar+N >= p->nAlloc ){
+    enlargeAndAppend(p,z,N);
     return;
   }
-    }
-  }
   assert( p->zText );
   memcpy(&p->zText[p->nChar], z, N);
   p->nChar += N;