From 6a51741d4657e1621db3cc8352b3c706be00a1d4 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Thu, 12 Nov 2009 03:46:34 +0000
Subject: [PATCH] Suppress excess OP_Null opcodes caused by binary IS or IS NOT
 operators that are converted into unary ISNULL or NOTNULL operators.

FossilOrigin-Name: cff1b36ab2c417611f59e96694005c03762788d2
---
 manifest      | 18 +++++++++---------
 manifest.uuid |  2 +-
 src/parse.y   | 21 +++++++++++++++------
 3 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/manifest b/manifest
index fe7c5990db..53303daffc 100644
--- a/manifest
+++ b/manifest
@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Adjustments\sto\sthe\simplementation\sof\sLIMIT\sso\sthat\sit\suses\sfewer\sopcodes.
-D 2009-11-12T03:13:26
+C Suppress\sexcess\sOP_Null\sopcodes\scaused\sby\sbinary\sIS\sor\sIS\sNOT\soperators\s\nthat\sare\sconverted\sinto\sunary\sISNULL\sor\sNOTNULL\soperators.
+D 2009-11-12T03:46:34
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 53f3dfa49f28ab5b80cb083fb7c9051e596bcfa1
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -153,7 +153,7 @@ F src/os_unix.c bdd6ca0932dcb51c344081aff430bcc71c14db7f
 F src/os_win.c 5ffab20249a61e0625f869efe157fa009747039b
 F src/pager.c 47343e340df799199fd1f1a184f0df8861519e1e
 F src/pager.h 1b32faf2e578ac3e7bcf9c9d11217128261c5c54
-F src/parse.y 0a36c62c090e7e5bb2e36f66909cf4a42c025e1b
+F src/parse.y f785d814562a14dc19202f61abb4372845f64752
 F src/pcache.c 3b079306376e0e04c0d3df40c0a4b750a1839310
 F src/pcache.h c683390d50f856d4cd8e24342ae62027d1bb6050
 F src/pcache1.c db4a996e456eec2380732a1036e23e3f551f6573
@@ -770,14 +770,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 8861b5c16031ad570ffbe17b3ec8163b136a7f63
-R 2e62411d417a05caf2dd89c1ca0e0fb5
+P 39d5b292d27faf00ab58ff4074f91f7aea97cd99
+R c19d84dba79b3abd8970106821a4d05d
 U drh
-Z e34f2d0325afcf3aef2ae5d8242ce5af
+Z 3cbf107f89243c15e854c8e3cdc20f73
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1.4.6 (GNU/Linux)
 
-iD8DBQFK+31aoxKgR168RlERAm5yAJoDGtDUZYQGDXxew/n6ZNZuiH02bwCfWGOF
-tQZHhWLWT4zFQub7T8BA6c4=
-=tCQs
+iD8DBQFK+4UeoxKgR168RlERAoVfAJ9p0PXyLRWA76+9khL8SSrXAwEe8gCeOt0X
+3oLu7ZH/IfhZcimL477cDUs=
+=cbgv
 -----END PGP SIGNATURE-----
diff --git a/manifest.uuid b/manifest.uuid
index 60bbcc4e0e..f007b77be6 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-39d5b292d27faf00ab58ff4074f91f7aea97cd99
\ No newline at end of file
+cff1b36ab2c417611f59e96694005c03762788d2
\ No newline at end of file
diff --git a/src/parse.y b/src/parse.y
index a47caa6850..89a0af0817 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -884,6 +884,19 @@ expr(A) ::= expr(X) likeop(OP) expr(Y) escape(E).  [LIKE_KW]  {
 expr(A) ::= expr(X) ISNULL|NOTNULL(E).   {spanUnaryPostfix(&A,pParse,@E,&X,&E);}
 expr(A) ::= expr(X) NOT NULL(E). {spanUnaryPostfix(&A,pParse,TK_NOTNULL,&X,&E);}
 
+%include {
+  /* A routine to convert a binary TK_IS or TK_ISNOT expression into a
+  ** unary TK_ISNULL or TK_NOTNULL expression. */
+  static void binaryToUnaryIfNull(Parse *pParse, Expr *pY, Expr *pA, int op){
+    sqlite3 *db = pParse->db;
+    if( db->mallocFailed==0 && pY->op==TK_NULL ){
+      pA->op = op;
+      sqlite3ExprDelete(db, pA->pRight);
+      pA->pRight = 0;
+    }
+  }
+}
+
 //    expr1 IS expr2
 //    expr1 IS NOT expr2
 //
@@ -892,15 +905,11 @@ expr(A) ::= expr(X) NOT NULL(E). {spanUnaryPostfix(&A,pParse,TK_NOTNULL,&X,&E);}
 // 
 expr(A) ::= expr(X) IS expr(Y).     {
   spanBinaryExpr(&A,pParse,TK_IS,&X,&Y);
-  if( pParse->db->mallocFailed==0  && Y.pExpr->op==TK_NULL ){
-    A.pExpr->op = TK_ISNULL;
-  }
+  binaryToUnaryIfNull(pParse, Y.pExpr, A.pExpr, TK_ISNULL);
 }
 expr(A) ::= expr(X) IS NOT expr(Y). {
   spanBinaryExpr(&A,pParse,TK_ISNOT,&X,&Y);
-  if( pParse->db->mallocFailed==0  && Y.pExpr->op==TK_NULL ){
-    A.pExpr->op = TK_NOTNULL;
-  }
+  binaryToUnaryIfNull(pParse, Y.pExpr, A.pExpr, TK_NOTNULL);
 }
 
 %include {
-- 
2.47.2