Revert "Do execGrouping.c via expression eval machinery."

This reverts commit 773aec7.

There's an unresolved issue in the reverted commit: It only creates
one comparator function, but in for the nodeSubplan.c case we need
more (c.f. FindTupleHashEntry vs LookupTupleHashEntry calls in
nodeSubplan.c).

This isn't too difficult to fix, but it's not entirely trivial
either. The fact that the issue only causes breakage on 32bit systems
shows that the current test coverage isn't that great.  To avoid
turning half the buildfarm red till those two issues are addressed,
revert.

Author: anarazel

src/backend/executor/execExpr.c

@@ -3193,121 +3193,3 @@ ExecBuildAggTransCall(ExprState *state, AggState *aggstate,
 		as->d.agg_strict_trans_check.jumpnull = state->steps_len;
 	}
 }
-
-/*
- * Build equality expression that can be evaluated using ExecQual(), returning
- * true if the expression context's inner/outer tuple are NOT DISTINCT. I.e
- * two nulls match, a null and a not-null don't match.
- *
- * desc: tuple descriptor of the to-be-compared tuples
- * numCols: the number of attributes to be examined
- * keyColIdx: array of attribute column numbers
- * eqFunctions: array of function oids of the equality functions to use
- * parent: parent executor node
- */
-ExprState *
-ExecBuildGroupingEqual(TupleDesc desc,
-					   int numCols,
-					   AttrNumber *keyColIdx,
-					   Oid *eqfunctions,
-					   PlanState *parent)
-{
-	ExprState  *state = makeNode(ExprState);
-	ExprEvalStep scratch = {0};
-	int			natt;
-	int			maxatt = -1;
-	List	   *adjust_jumps = NIL;
-	ListCell   *lc;
-
-	/*
-	 * When no columns are actually compared, the result's always true. See
-	 * special case in ExecQual().
-	 */
-	if (numCols == 0)
-		return NULL;
-
-	state->expr = NULL;
-	state->flags = EEO_FLAG_IS_QUAL;
-	state->parent = parent;
-
-	scratch.resvalue = &state->resvalue;
-	scratch.resnull = &state->resnull;
-
-	/* compute max needed attribute */
-	for (natt = 0; natt < numCols; natt++)
-	{
-		int			attno = keyColIdx[natt];
-
-		if (attno > maxatt)
-			maxatt = attno;
-	}
-	Assert(maxatt >= 0);
-
-	/* push deform steps */
-	scratch.opcode = EEOP_INNER_FETCHSOME;
-	scratch.d.fetch.last_var = maxatt;
-	ExprEvalPushStep(state, &scratch);
-
-	scratch.opcode = EEOP_OUTER_FETCHSOME;
-	scratch.d.fetch.last_var = maxatt;
-	ExprEvalPushStep(state, &scratch);
-
-	/*
-	 * Start comparing at the last field (least significant sort key). That's
-	 * the most likely to be different if we are dealing with sorted input.
-	 */
-	for (natt = numCols; --natt >= 0;)
-	{
-		int			attno = keyColIdx[natt];
-		Form_pg_attribute att = TupleDescAttr(desc, attno - 1);
-		Var		   *larg,
-				   *rarg;
-		List	   *args;
-
-		/*
-		 * Reusing ExecInitFunc() requires creating Vars, but still seems
-		 * worth it from a code reuse perspective.
-		 */
-
-		/* left arg */
-		larg = makeVar(INNER_VAR, attno, att->atttypid,
-					   att->atttypmod, InvalidOid, 0);
-		/* right arg */
-		rarg = makeVar(OUTER_VAR, attno, att->atttypid,
-					   att->atttypmod, InvalidOid, 0);
-		args = list_make2(larg, rarg);
-
-		/* evaluate distinctness */
-		ExecInitFunc(&scratch, NULL,
-					 args, eqfunctions[natt], InvalidOid,
-					 state);
-		scratch.opcode = EEOP_NOT_DISTINCT;
-		ExprEvalPushStep(state, &scratch);
-
-		/* then emit EEOP_QUAL to detect if result is false (or null) */
-		scratch.opcode = EEOP_QUAL;
-		scratch.d.qualexpr.jumpdone = -1;
-		ExprEvalPushStep(state, &scratch);
-		adjust_jumps = lappend_int(adjust_jumps,
-								   state->steps_len - 1);
-	}
-
-	/* adjust jump targets */
-	foreach(lc, adjust_jumps)
-	{
-		ExprEvalStep *as = &state->steps[lfirst_int(lc)];
-
-		Assert(as->opcode == EEOP_QUAL);
-		Assert(as->d.qualexpr.jumpdone == -1);
-		as->d.qualexpr.jumpdone = state->steps_len;
-	}
-
-	scratch.resvalue = NULL;
-	scratch.resnull = NULL;
-	scratch.opcode = EEOP_DONE;
-	ExprEvalPushStep(state, &scratch);
-
-	ExecReadyExpr(state);
-
-	return state;
-}

src/backend/executor/execExprInterp.c

@@ -355,7 +355,6 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 		&&CASE_EEOP_MAKE_READONLY,
 		&&CASE_EEOP_IOCOERCE,
 		&&CASE_EEOP_DISTINCT,
-		&&CASE_EEOP_NOT_DISTINCT,
 		&&CASE_EEOP_NULLIF,
 		&&CASE_EEOP_SQLVALUEFUNCTION,
 		&&CASE_EEOP_CURRENTOFEXPR,
@@ -1199,34 +1198,6 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 			EEO_NEXT();
 		}
 
-		/* see EEOP_DISTINCT for comments, this is just inverted */
-		EEO_CASE(EEOP_NOT_DISTINCT)
-		{
-			FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
-
-			if (fcinfo->argnull[0] && fcinfo->argnull[1])
-			{
-				*op->resvalue = BoolGetDatum(true);
-				*op->resnull = false;
-			}
-			else if (fcinfo->argnull[0] || fcinfo->argnull[1])
-			{
-				*op->resvalue = BoolGetDatum(false);
-				*op->resnull = false;
-			}
-			else
-			{
-				Datum		eqresult;
-
-				fcinfo->isnull = false;
-				eqresult = op->d.func.fn_addr(fcinfo);
-				*op->resvalue = eqresult;
-				*op->resnull = fcinfo->isnull;
-			}
-
-			EEO_NEXT();
-		}
-
 		EEO_CASE(EEOP_NULLIF)
 		{
 			/*