From bcedbb2781e2fc9acca1ea926e52525e255e279e Mon Sep 17 00:00:00 2001
From: drh <>
Date: Mon, 28 Mar 2022 18:34:40 +0000
Subject: [PATCH] Further size and performance optimizations for
 sqlite3VdbeMemSetStr().

FossilOrigin-Name: 310a3e102d8eedf92ee63ffffb48621abfb1e2736b96bd2a676d63cca0f40598
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/vdbemem.c | 46 ++++++++++++++++++++++++++--------------------
 3 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/manifest b/manifest
index b3b35b83e2..d6dc655417 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Slightly\ssmaller\sand\sfaster\ssqlite3VdbeMemSetStr().
-D 2022-03-28T17:34:46.798
+C Further\ssize\sand\sperformance\soptimizations\sfor\ssqlite3VdbeMemSetStr().
+D 2022-03-28T18:34:40.795
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -630,7 +630,7 @@ F src/vdbeInt.h 8dd91427155a38ec06e9ecbde07e33f21bc02e101625191e7613f883e379a363
 F src/vdbeapi.c bc3812dff7c9e6497c87ae86962818a51f66f8d7a873e7ec02a22aa115b84799
 F src/vdbeaux.c 1de06d17a1af1bf5cc776e60afcc01c49438df90863fc4db0a0516060e7b959a
 F src/vdbeblob.c 5e61ce31aca17db8fb60395407457a8c1c7fb471dde405e0cd675974611dcfcd
-F src/vdbemem.c 4fdef7b1dadb7073ea6c20f366f84cce5e01f8795317d4fd55cf2c9d6e5febf4
+F src/vdbemem.c dc02c6b8d51bcfc50f02266cb7003395d2989b72a9df6be561fcecdf16040784
 F src/vdbesort.c 43756031ca7430f7aec3ef904824a7883c4ede783e51f280d99b9b65c0796e35
 F src/vdbetrace.c fe0bc29ebd4e02c8bc5c1945f1d2e6be5927ec12c06d89b03ef2a4def34bf823
 F src/vdbevtab.c f99b275366c5fc5e2d99f734729880994ab9500bdafde7fae3b02d562b9d323c
@@ -1945,8 +1945,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 4ccebb86aae178dbce905d782f04d98211f8fce9aacd71c12b8694c92a4f5c40
-R d5c1e4092f171ba4e7d9a62fbfe55090
+P 06928e745c7bcb26ec46a17989f30efe3536fd48a74c8a1cd423cc9ff6feccb5
+R e5b296feee8b6ff8861e4cf66944c654
 U drh
-Z 6eb24c52f69c2c05bf470575314084b5
+Z 8d86ba5638b23b699bb683c424e71903
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 33159274fb..17903a1e91 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-06928e745c7bcb26ec46a17989f30efe3536fd48a74c8a1cd423cc9ff6feccb5
\ No newline at end of file
+310a3e102d8eedf92ee63ffffb48621abfb1e2736b96bd2a676d63cca0f40598
\ No newline at end of file
diff --git a/src/vdbemem.c b/src/vdbemem.c
index b41b13e2f5..524280e0df 100644
--- a/src/vdbemem.c
+++ b/src/vdbemem.c
@@ -1124,7 +1124,7 @@ int sqlite3VdbeMemSetStr(
 ){
   i64 nByte = n;      /* New value for pMem->n */
   int iLimit;         /* Maximum allowed string or blob size */
-  u16 flags = 0;      /* New value for pMem->flags */
+  u16 flags;          /* New value for pMem->flags */
 
   assert( pMem!=0 );
   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
@@ -1149,9 +1149,27 @@ int sqlite3VdbeMemSetStr(
     }else{
       for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
     }
-    flags|= MEM_Str|MEM_Term;
+    flags= MEM_Str|MEM_Term;
+  }else if( enc==0 ){
+    flags = MEM_Blob;
+#ifdef SQLITE_ENABLE_SESSION
+    enc = pMem->db ? ENC(pMem->db) : SQLITE_UTF8;
+#else
+    assert( pMem->db!=0 );
+    enc = ENC(pMem->db);
+#endif
   }else{
-    flags = (enc==0?MEM_Blob:MEM_Str);
+    flags = MEM_Str;
+  }
+  if( nByte>iLimit ){
+    if( xDel && xDel!=SQLITE_TRANSIENT ){
+      if( xDel==SQLITE_DYNAMIC ){
+        sqlite3DbFree(pMem->db, (void*)z);
+      }else{
+        xDel((void*)z);
+      }
+    }
+    return sqlite3ErrorToParser(pMem->db, SQLITE_TOOBIG);
   }
 
   /* The following block sets the new values of Mem.z and Mem.xDel. It
@@ -1163,9 +1181,6 @@ int sqlite3VdbeMemSetStr(
     if( flags&MEM_Term ){
       nAlloc += (enc==SQLITE_UTF8?1:2);
     }
-    if( nByte>iLimit ){
-      return sqlite3ErrorToParser(pMem->db, SQLITE_TOOBIG);
-    }
     testcase( nAlloc==0 );
     testcase( nAlloc==31 );
     testcase( nAlloc==32 );
@@ -1187,26 +1202,17 @@ int sqlite3VdbeMemSetStr(
 
   pMem->n = (int)(nByte & 0x7fffffff);
   pMem->flags = flags;
-  if( enc ){
-    pMem->enc = enc;
-#ifdef SQLITE_ENABLE_SESSION
-  }else if( pMem->db==0 ){
-    pMem->enc = SQLITE_UTF8;
-#endif
-  }else{
-    assert( pMem->db!=0 );
-    pMem->enc = ENC(pMem->db);
-  }
+  pMem->enc = enc;
 
 #ifndef SQLITE_OMIT_UTF16
-  if( enc>SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
+  if( enc>SQLITE_UTF8
+   && (flags & MEM_Blob)==0
+   && sqlite3VdbeMemHandleBom(pMem)
+  ){
     return SQLITE_NOMEM_BKPT;
   }
 #endif
 
-  if( nByte>iLimit ){
-    return sqlite3ErrorToParser(pMem->db, SQLITE_TOOBIG);
-  }
 
   return SQLITE_OK;
 }