Do not reuse temp registers originally allocated to a subroutine within

the main body of the program logic, since if the subroutine is called
while the reused temp registers are in use, their values will get clobbered.
Candidate fix for ticket [3a77c9714e63330]

FossilOrigin-Name: 092d53315e50be42b51ef7b3069c82c32a129b6a

manifest

@@ -1,5 +1,5 @@
-C Merge\sthe\swinGetLastError\sfixes\sinto\strunk.
-D 2011-12-06T00:47:51.936
+C Do\snot\sreuse\stemp\sregisters\soriginally\sallocated\sto\sa\ssubroutine\swithin\nthe\smain\sbody\sof\sthe\sprogram\slogic,\ssince\sif\sthe\ssubroutine\sis\scalled\nwhile\sthe\sreused\stemp\sregisters\sare\sin\suse,\stheir\svalues\swill\sget\sclobbered.\nCandidate\sfix\sfor\sticket\s[3a77c9714e63330]
+D 2011-12-06T13:24:59.067
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 5b4a3e12a850b021547e43daf886b25133b44c07
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -134,7 +134,7 @@ F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
 F src/ctime.c a9c26822515f81ec21588cbb482ca6724be02e33
 F src/date.c 067a81c9942c497aafd2c260e13add8a7d0c7dd4
 F src/delete.c 51d32f0a9c880663e54ce309f52e40c325d5e112
-F src/expr.c fbf116f90cabc917ae50bba24a73a0b55519a0c8
+F src/expr.c 319db0ad9f3c5d039d54bf5a65c98c08c7233924
 F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
 F src/fkey.c 657212460bf5cfd3ae607d12ea62092844c227b5
 F src/func.c 6261ce00aad9c63cd5b4219249b05683979060e9
@@ -180,11 +180,11 @@ F src/printf.c 03104cbff6959ff45df69dc9060ba6212f60a869
 F src/random.c cd4a67b3953b88019f8cd4ccd81394a8ddfaba50
 F src/resolve.c 365ab1c870e38596d6869e76fb544fe6e4ffc809
 F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697
-F src/select.c 80f3ac44a8514b1d107b80f5df4a424ae059d2b6
+F src/select.c 538b5f096f6aacedf717bf982f9ad9a901008514
 F src/shell.c 29812a900a780eb0f835c4bc65e216272689def8
 F src/sqlite.h.in 57081d8e6b53ce29541d7437c93bce6087ac53b5
 F src/sqlite3ext.h 6904f4aadf976f95241311fbffb00823075d9477
-F src/sqliteInt.h 6f28b69d77356b1e45c024a6c103a1e0f0ec9f62
+F src/sqliteInt.h 142ef5ed3fe0e6c662e99dbf92f38715b29a53b6
 F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
 F src/status.c 4568e72dfd36b6a5911f93457364deb072e0b03a
 F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@@ -976,7 +976,7 @@ F tool/tostr.awk e75472c2f98dd76e06b8c9c1367f4ab07e122d06
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
 F tool/warnings-clang.sh 9f406d66e750e8ac031c63a9ef3248aaa347ef2a
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
-P 431556cac0b2c86d7f6a60412ff1023feeaafedf 7e657bbb800107c992a6ee7a3b35bc0a073bf3e4
-R 543654dfa3532b18db5b62d6f330a3c2
+P 5b03ba9db0d23a8597b45e00ad5892c8065ce1cd
+R 9fd2e18e31f5993e2a2417d0bd31fbb8
 U drh
-Z d9a349b5feef66c92d693305f283c870
+Z 6b588a9e7cf08c9f198f7cca1fb8c358

manifest.uuid

@@ -1 +1 @@
-5b03ba9db0d23a8597b45e00ad5892c8065ce1cd
+092d53315e50be42b51ef7b3069c82c32a129b6a

src/expr.c

@@ -3762,3 +3762,11 @@ void sqlite3ReleaseTempRange(Parse *pParse, int iReg, int nReg){
     pParse->iRangeReg = iReg;
   }
 }
+
+/*
+** Mark all temporary registers as being unavailable for reuse.
+*/
+void sqlite3ClearTempRegCache(Parse *pParse){
+  pParse->nTempReg = 0;
+  pParse->nRangeReg = 0;
+}

src/select.c

@@ -3860,7 +3860,7 @@ int sqlite3Select(
       retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
       VdbeComment((v, "end %s", pItem->pTab->zName));
       sqlite3VdbeChangeP1(v, topAddr, retAddr);
-
+      sqlite3ClearTempRegCache(pParse);
     }
     if( /*pParse->nErr ||*/ db->mallocFailed ){
       goto select_end;

src/sqliteInt.h

@@ -2660,6 +2660,7 @@ int sqlite3GetTempReg(Parse*);
 void sqlite3ReleaseTempReg(Parse*,int);
 int sqlite3GetTempRange(Parse*,int);
 void sqlite3ReleaseTempRange(Parse*,int,int);
+void sqlite3ClearTempRegCache(Parse*);
 Expr *sqlite3ExprAlloc(sqlite3*,int,const Token*,int);
 Expr *sqlite3Expr(sqlite3*,int,const char*);
 void sqlite3ExprAttachSubtrees(sqlite3*,Expr*,Expr*,Expr*);