diff --git a/manifest b/manifest
index 1a98ce06e0..ce0a96a9df 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Document\sthe\s"%token"\sdirective\sfor\sLemon.\s\sThis\sdirective\shas\sbeen\sin\splace\nfor\sa\swhile,\sbut\swas\spreviously\sundocumented.
-D 2021-03-28T20:44:01.313
+C Alternative\simplementation\sof\sthe\scomparison\sopcode\sspeed-up\sof\ncheck-in\s[4a8805d9a66dc888]\sthat\sshould\spass\smuster\swith\sUBSAN.
+D 2021-03-28T23:37:56.856
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -498,7 +498,7 @@ F src/expr.c 030391f7a19e74e10ce9f2791f26158b34ee303c13993add67dff87501673d49
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c e9063648396c58778f77583a678342fe4a9bc82436bf23c5f9f444f2df0fdaa4
 F src/func.c 479f6929be027eb0210cbdde9d3529c012facf082d64a6b854a9415940761e5e
-F src/global.c ed55af196a9b66e198aaeda3f5454c3aa7d7d050c6c938181fd044b70d180a81
+F src/global.c 56d6762a3a44495ab035e2d3185eeccbc98579e18c06038e1bb9af346105bc84
 F src/hash.c 8d7dda241d0ebdafb6ffdeda3149a412d7df75102cecfc1021c98d6219823b19
 F src/hash.h 9d56a9079d523b648774c1784b74b89bd93fac7b365210157482e4319a468f38
 F src/hwtime.h cb1d7e3e1ed94b7aa6fde95ae2c2daccc3df826be26fc9ed7fd90d1750ae6144
@@ -547,7 +547,7 @@ F src/shell.c.in dcce260883836c9b58847505fbccce8d5546af925046f7dacd9443e922ece03
 F src/sqlite.h.in 3426a080ea1f222a73e3bd91e7eacbd30570a0117c03d42c6dde606f33e5e318
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 61b38c073d5e1e96a3d45271b257aef27d0d13da2bea5347692ae579475cd95e
-F src/sqliteInt.h 87bb2f645fcd6f2b7dbf41f85777d3c24a4b08e73c7153741cdd0481e9ab213d
+F src/sqliteInt.h 1330dbc07b9d411a7502aba076f7fe17719457cd4dd24c164d956a06b4a4acb9
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
 F src/status.c 4b8bc2a6905163a38b739854a35b826c737333fab5b1f8e03fa7eb9a4799c4c1
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -614,7 +614,7 @@ F src/upsert.c df8f1727d62b5987c4fd302cd4d7c0c84ae57cd65683c5a34a740dfe24039235
 F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
 F src/util.c 41c7a72da1df47864faa378a1c720b38adb288c6838cb6be5594511b6287a048
 F src/vacuum.c 492422c1463c076473bae1858799c7a0a5fe87a133d1223239447c422cd26286
-F src/vdbe.c 5001a0d3003d3664615dd7ac3cedab1d51e2391b5bdd0878f40a41fdcd942e13
+F src/vdbe.c c626ed23dedf2501e1cd97bc3e3e78dd95fc773c507827b0a0ba3cf14b008142
 F src/vdbe.h 25dabb25c7e157b84e59260cfb5b466c3ac103ede9f36f4db371332c47601abe
 F src/vdbeInt.h 000d9ab1ea4cb55a80de15e28f3f595645b4fddef34bca4347fb3db8031d9041
 F src/vdbeapi.c 4a43e303ec3354c785f453e881521969378e85628278ab74ba4a9df790c0d93b
@@ -1911,7 +1911,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P c23d092f37c535f88a47e9f55aa7b2fd40cfd5c50eec9191a68073d7f9141ecd
-R 1962b187e50d8ed528041ea3add6901a
+P 36624d3740a8d095eee061bcc5037deabddb88a53444ec1a956a8af7684efa43
+R 66682903058dce39de324695f35d0b74
 U drh
-Z 89ccc7976bdb2c2ae9dddc0aacedcb7d
+Z 8dbf744cc2e2ce2434fc7ddbd088d521
diff --git a/manifest.uuid b/manifest.uuid
index 1a5f646995..4cf95da347 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-36624d3740a8d095eee061bcc5037deabddb88a53444ec1a956a8af7684efa43
\ No newline at end of file
+afb18f64541effaeaada2d72c7c91adfe5ec3e2b1418c0bc281083125fb5badb
\ No newline at end of file
diff --git a/src/global.c b/src/global.c
index b5239ad81a..10c368f723 100644
--- a/src/global.c
+++ b/src/global.c
@@ -37,7 +37,7 @@ const unsigned char sqlite3UpperToLower[] = {
     198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
     216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
     234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
-    252,253,254,255
+    252,253,254,255,
 #endif
 #ifdef SQLITE_EBCDIC
       0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, /* 0x */
@@ -57,7 +57,35 @@ const unsigned char sqlite3UpperToLower[] = {
     224,225,162,163,164,165,166,167,168,169,234,235,236,237,238,239, /* Ex */
     240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255, /* Fx */
 #endif
+/* All of the upper-to-lower conversion data is above.  The following
+** 18 integers are completely unrelated.  They are appended to the
+** sqlite3UpperToLower[] array to avoid UBSAN warnings.  Here's what is
+** going on:
+**
+** The SQL comparison operators (<>, =, >, <=, <, and >=) are implemented
+** by invoking sqlite3MemCompare(A,B) which compares values A and B and
+** returns negative, zero, or positive if A is less then, equal to, or
+** greater than B, respectively.  Then the true false results is found by
+** consulting sqlite3aLTb[opcode], sqlite3aEQb[opcode], or 
+** sqlite3aGTb[opcode] depending on whether the result of compare(A,B)
+** is negative, zero, or positive, where opcode is the specific opcode.
+** The only works because the comparison opcodes are consecutive and in
+** this order: NE EQ GT LE LT GE.  Various assert()s throughout the code
+** ensure that is the case.
+**
+** These elements must be appended to another array.  Otherwise the
+** index (here shown as [256-OP_Ne]) would be out-of-bounds and thus
+** be undefined behavior.  That's goofy, but the C-standards people thought
+** it was a good idea, so here we are.
+*/
+/* NE  EQ  GT  LE  LT  GE  */
+   1,  0,  0,  1,  1,  0,  /* aLTb[]: Use when compare(A,B) less than zero */
+   0,  1,  0,  1,  0,  1,  /* aEQb[]: Use when compare(A,B) equals zero */
+   1,  0,  1,  0,  0,  1   /* aGTb[]: Use when compare(A,B) greater than zero*/
 };
+const unsigned char *sqlite3aLTb = &sqlite3UpperToLower[256-OP_Ne];
+const unsigned char *sqlite3aEQb = &sqlite3UpperToLower[256+6-OP_Ne];
+const unsigned char *sqlite3aGTb = &sqlite3UpperToLower[256+12-OP_Ne];
 
 /*
 ** The following 256 byte lookup table is used to support SQLites built-in
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 0822a6c3c4..cd2e9a2e29 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -4739,6 +4739,9 @@ void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
 extern const unsigned char sqlite3OpcodeProperty[];
 extern const char sqlite3StrBINARY[];
 extern const unsigned char sqlite3UpperToLower[];
+extern const unsigned char *sqlite3aLTb;
+extern const unsigned char *sqlite3aEQb;
+extern const unsigned char *sqlite3aGTb;
 extern const unsigned char sqlite3CtypeMap[];
 extern SQLITE_WSD struct Sqlite3Config sqlite3Config;
 extern FuncDefHash sqlite3BuiltinFunctions;
diff --git a/src/vdbe.c b/src/vdbe.c
index 080c7eaf83..0026ed377b 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -2111,15 +2111,12 @@ compare_op:
   ** order:  NE, EQ, GT, LE, LT, GE */
   assert( OP_Eq==OP_Ne+1 ); assert( OP_Gt==OP_Ne+2 ); assert( OP_Le==OP_Ne+3 );
   assert( OP_Lt==OP_Ne+4 ); assert( OP_Ge==OP_Ne+5 );
-  if( res<0 ){                        /* ne, eq, gt, le, lt, ge */
-    static const unsigned char aLTb[] = { 1,  0,  0,  1,  1,  0 };
-    res2 = aLTb[pOp->opcode - OP_Ne];
+  if( res<0 ){
+    res2 = sqlite3aLTb[pOp->opcode];
   }else if( res==0 ){
-    static const unsigned char aEQb[] = { 0,  1,  0,  1,  0,  1 };
-    res2 = aEQb[pOp->opcode - OP_Ne];
+    res2 = sqlite3aEQb[pOp->opcode];
   }else{
-    static const unsigned char aGTb[] = { 1,  0,  1,  0,  0,  1 };
-    res2 = aGTb[pOp->opcode - OP_Ne];
+    res2 = sqlite3aGTb[pOp->opcode];
   }
 
   /* Undo any changes made by applyAffinity() to the input registers. */