diff --git a/manifest b/manifest
index 3a5afaeadc..d1b23d0aac 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sthe\sparsing\sof\sC-style\scomments\sin\sLemon,\sas\sreported\sby\n[forum:/forumpost/b6edc69548|forum\spost\sb6edc69548].\s\sThis\shas\sno\saffect\non\sSQLite\sitself.
-D 2022-04-07T14:13:32.478
+C The\s".testctrl\soptimizations\s0x400000"\scommand\sdisables\sthe\sgeneration\sof\nOP_ReleaseReg\sopcodes.\s\sOP_ReleaseReg\sopcodes\sare\susually\sonly\sgenerated\sfor\nSQLITE_DEBUG\sbuilds\sand\sare\sused\sto\sverify\sthat\sregisters\sare\sdescoped\npropertly.\s\sBut\sthey\scan\sget\sin\sthe\sway\sof\scode\sunderstanding\swhen\sstudying\nbytecode\sdumps.\s\sSo\sthis\snew\soptimization\ssetting\sis\sprovided\sto\ntemporarily\sturn\sOP_ReleaseReg\sopcodes\soff.
+D 2022-04-07T18:17:56.434
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -557,7 +557,7 @@ F src/shell.c.in 18832612e74c92bbd25d88e1f92685f66589262f68cca1001d2a43bd6dd0ed6
 F src/sqlite.h.in 2a35f62185eb5e7ecc64a2f68442b538ce9be74f80f28a00abc24837edcf1c17
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h f49e28c25bd941e79794db5415fdf7b202deb3bc072ed6f1ed273d578703684e
-F src/sqliteInt.h dbd5537c36a6b01fd67890487c3f7da468f16845500c115886f20adec06869ca
+F src/sqliteInt.h 8262a5a484ffc0c0899537c9d99fff381f2d76061e256592a342bc098860a6ec
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
 F src/status.c 4a3da6d77eeb3531cb0dbdf7047772a2a1b99f98c69e90ce009c75fe6328b2c0
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -628,7 +628,7 @@ F src/vdbe.c 4d8f5b013e1ad47240e9822217a4ac76041afd2667dcbefd26f598fe45f729a5
 F src/vdbe.h 89f5edb1422c8783a0b29db836e409876f2b3e847f78e2b21b1fbcc48a93f85f
 F src/vdbeInt.h 5f3d0abcf30c2b7a6672ad4386f18be0fca9c9b2cefe18f85a2e3df74f2613bf
 F src/vdbeapi.c 354c893f1500cf524cc45c32879b9c68893a28b77e3442c24668d6afe4236217
-F src/vdbeaux.c 567ddcdd5d875161201e9752144834d1519e7e856e2da410619d88a9cfefe70d
+F src/vdbeaux.c baafd56664ccca4cf361a48b912f7ff37f95ee19aaf7cada420ce2ca73396833
 F src/vdbeblob.c 5e61ce31aca17db8fb60395407457a8c1c7fb471dde405e0cd675974611dcfcd
 F src/vdbemem.c 7189090b72baa025f945a1ac8c61ee420c645254476e8a191d555db76dfea5d4
 F src/vdbesort.c 43756031ca7430f7aec3ef904824a7883c4ede783e51f280d99b9b65c0796e35
@@ -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 5043a3507e0781878e0e1bea5095a33273958820baead4af8fc2929e9d7c07ee
-R 3aa1ea2fb3309b52d9b9b355614ccef2
+P 201569e09b000919ccb463bd581fb2ecd5320e7f584fdb1bc2aaba111061d5c3
+R 3b3b7a8904349e1fc968ddd3854c9c21
 U drh
-Z a9f6250e4b921e7cc5eba2670fe5b4ea
+Z 053f375f9db373c4b27ef764e92f78d7
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 604ab9337a..70d47c032f 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-201569e09b000919ccb463bd581fb2ecd5320e7f584fdb1bc2aaba111061d5c3
\ No newline at end of file
+fa5276725f246cef9d58b27c1e617ee3f873f7a9b88284a4e8fc453ebda338bc
\ No newline at end of file
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 9f95ec8a9d..a9f3121c7c 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1779,6 +1779,7 @@ struct sqlite3 {
 #define SQLITE_BloomFilter    0x00080000 /* Use a Bloom filter on searches */
 #define SQLITE_BloomPulldown  0x00100000 /* Run Bloom filters early */
 #define SQLITE_BalancedMerge  0x00200000 /* Balance multi-way merges */
+#define SQLITE_ReleaseReg     0x00400000 /* Use OP_ReleaseReg for testing */
 #define SQLITE_AllOpts        0xffffffff /* All optimizations */
 
 /*
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 551236226b..cb2433c2cd 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -1231,7 +1231,7 @@ void sqlite3VdbeReleaseRegisters(
   u32 mask,            /* Mask of registers to NOT release */
   int bUndefine        /* If true, mark registers as undefined */
 ){
-  if( N==0 ) return;
+  if( N==0 || OptimizationDisabled(pParse->db, SQLITE_ReleaseReg) ) return;
   assert( pParse->pVdbe );
   assert( iFirst>=1 );
   assert( iFirst+N-1<=pParse->nMem );