Improvements to register allocation, especially in the ANALYZE command.

New assert() statements added to help verify that memory allocation is
correct, and to help fuzzer find lingering errors.

FossilOrigin-Name: 6f8b97f31a4c8552312b4c98432ea356ae54c06d9cc929969f50c3c88360cd7b

1 files changed, 37 insertions, 0 deletions

diff --git a/src/expr.c b/src/expr.c
index cd09c0d71..564dfc7fb 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -6636,6 +6636,35 @@ void sqlite3ClearTempRegCache(Parse *pParse){
 }
 
 /*
+** Make sure sufficient registers have been allocated so that
+** iReg is a valid register number.
+*/
+void sqlite3TouchRegister(Parse *pParse, int iReg){
+  if( pParse->nMem<iReg ) pParse->nMem = iReg;
+}
+
+/*
+** Return the latest reusable register in the set of all registers.
+** The value returned is no less than iMin.  If any register iMin or
+** greater is in permanent use, then return one more than that last
+** permanent register.
+*/
+int sqlite3FirstAvailableRegister(Parse *pParse, int iMin){
+  const ExprList *pList = pParse->pConstExpr;
+  if( pList ){
+    int i;
+    for(i=0; i<pList->nExpr; i++){
+      if( pList->a[i].u.iConstExprReg>=iMin ){
+        iMin = pList->a[i].u.iConstExprReg + 1;
+      }
+    }
+  }
+  pParse->nTempReg = 0;
+  pParse->nRangeReg = 0;
+  return iMin;
+}
+
+/*
 ** Validate that no temporary register falls within the range of
 ** iFirst..iLast, inclusive.  This routine is only call from within assert()
 ** statements.
@@ -6654,6 +6683,14 @@ int sqlite3NoTempsInRange(Parse *pParse, int iFirst, int iLast){
       return 0;
     }
   }
+  if( pParse->pConstExpr ){
+    ExprList *pList = pParse->pConstExpr;
+    for(i=0; i<pList->nExpr; i++){
+      int iReg = pList->a[i].u.iConstExprReg;
+      if( iReg==0 ) continue;
+      if( iReg>=iFirst && iReg<=iLast ) return 0;
+    }
+  }
   return 1;
 }
 #endif /* SQLITE_DEBUG */