[release-18.0] Fix nullability checks in evalengine (#14556)

go/mysql/collations/integration/main_test.go

@@ -47,7 +47,7 @@ func mysqlconn(t *testing.T) *mysql.Conn {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !strings.HasPrefix(conn.ServerVersion, "8.0.") {
+	if !strings.HasPrefix(conn.ServerVersion, "8.") {
 		conn.Close()
 		t.Skipf("collation integration tests are only supported in MySQL 8.0+")
 	}

go/vt/vtgate/evalengine/compiler_asm.go

@@ -528,7 +528,7 @@ func (asm *assembler) CmpCase(cases int, hasElse bool, tt sqltypes.Type, cc coll
 	asm.emit(func(env *ExpressionEnv) int {
 		end := env.vm.sp - elseOffset
 		for sp := env.vm.sp - stackDepth; sp < end; sp += 2 {
-			if env.vm.stack[sp].(*evalInt64).i != 0 {
+			if env.vm.stack[sp] != nil && env.vm.stack[sp].(*evalInt64).i != 0 {
 				env.vm.stack[env.vm.sp-stackDepth], env.vm.err = evalCoerce(env.vm.stack[sp+1], tt, cc.Collation)
 				goto done
 			}
@@ -782,16 +782,18 @@ func (asm *assembler) Convert_bB(offset int) {
 		var f float64
 		if arg != nil {
 			f, _ = fastparse.ParseFloat64(arg.(*evalBytes).string())
+			env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(f != 0.0)
 		}
-		env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(f != 0.0)
 		return 1
 	}, "CONV VARBINARY(SP-%d), BOOL", offset)
 }
 
 func (asm *assembler) Convert_TB(offset int) {
 	asm.emit(func(env *ExpressionEnv) int {
 		arg := env.vm.stack[env.vm.sp-offset]
-		env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg != nil && !arg.(*evalTemporal).isZero())
+		if arg != nil {
+			env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(!arg.(*evalTemporal).isZero())
+		}
 		return 1
 	}, "CONV SQLTYPES(SP-%d), BOOL", offset)
 }
@@ -839,7 +841,9 @@ func (asm *assembler) Convert_Tj(offset int) {
 func (asm *assembler) Convert_dB(offset int) {
 	asm.emit(func(env *ExpressionEnv) int {
 		arg := env.vm.stack[env.vm.sp-offset]
-		env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg != nil && !arg.(*evalDecimal).dec.IsZero())
+		if arg != nil {
+			env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(!arg.(*evalDecimal).dec.IsZero())
+		}
 		return 1
 	}, "CONV DECIMAL(SP-%d), BOOL", offset)
 }
@@ -859,7 +863,9 @@ func (asm *assembler) Convert_dbit(offset int) {
 func (asm *assembler) Convert_fB(offset int) {
 	asm.emit(func(env *ExpressionEnv) int {
 		arg := env.vm.stack[env.vm.sp-offset]
-		env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg != nil && arg.(*evalFloat).f != 0.0)
+		if arg != nil {
+			env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg.(*evalFloat).f != 0.0)
+		}
 		return 1
 	}, "CONV FLOAT64(SP-%d), BOOL", offset)
 }
@@ -906,7 +912,9 @@ func (asm *assembler) Convert_Tf(offset int) {
 func (asm *assembler) Convert_iB(offset int) {
 	asm.emit(func(env *ExpressionEnv) int {
 		arg := env.vm.stack[env.vm.sp-offset]
-		env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg != nil && arg.(*evalInt64).i != 0)
+		if arg != nil {
+			env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg.(*evalInt64).i != 0)
+		}
 		return 1
 	}, "CONV INT64(SP-%d), BOOL", offset)
 }
@@ -986,7 +994,9 @@ func (asm *assembler) Convert_Nj(offset int) {
 func (asm *assembler) Convert_uB(offset int) {
 	asm.emit(func(env *ExpressionEnv) int {
 		arg := env.vm.stack[env.vm.sp-offset]
-		env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg != nil && arg.(*evalUint64).u != 0)
+		if arg != nil {
+			env.vm.stack[env.vm.sp-offset] = env.vm.arena.newEvalBool(arg.(*evalUint64).u != 0)
+		}
 		return 1
 	}, "CONV UINT64(SP-%d), BOOL", offset)
 }

go/vt/vtgate/evalengine/compiler_test.go

@@ -455,6 +455,38 @@ func TestCompilerSingle(t *testing.T) {
 			expression: `WEIGHT_STRING('foobar' as char(3))`,
 			result:     `VARBINARY("\x1c\xe5\x1d\xdd\x1d\xdd")`,
 		},
+		{
+			expression: `cast(null * 1 as CHAR)`,
+			result:     `NULL`,
+		},
+		{
+			expression: `cast(null + 1 as CHAR)`,
+			result:     `NULL`,
+		},
+		{
+			expression: `cast(null - 1 as CHAR)`,
+			result:     `NULL`,
+		},
+		{
+			expression: `cast(null / 1 as CHAR)`,
+			result:     `NULL`,
+		},
+		{
+			expression: `cast(null % 1 as CHAR)`,
+			result:     `NULL`,
+		},
+		{
+			expression: `1 AND NULL * 1`,
+			result:     `NULL`,
+		},
+		{
+			expression: `case 0 when NULL then 1 else 0 end`,
+			result:     `INT64(0)`,
+		},
+		{
+			expression: `case when null is null then 23 else null end`,
+			result:     `INT64(23)`,
+		},
 	}
 
 	for _, tc := range testCases {

go/vt/vtgate/evalengine/expr_arithmetic.go

@@ -191,7 +191,7 @@ func (op *opArithAdd) compile(c *compiler, left, right Expr) (ctype, error) {
 	}
 
 	c.asm.jumpDestination(skip1, skip2)
-	return ctype{Type: sumtype, Col: collationNumeric}, nil
+	return ctype{Type: sumtype, Flag: nullableFlags(lt.Flag | rt.Flag), Col: collationNumeric}, nil
 }
 
 func (op *opArithSub) eval(left, right eval) (eval, error) {
@@ -274,7 +274,7 @@ func (op *opArithSub) compile(c *compiler, left, right Expr) (ctype, error) {
 	}
 
 	c.asm.jumpDestination(skip1, skip2)
-	return ctype{Type: subtype, Col: collationNumeric}, nil
+	return ctype{Type: subtype, Flag: nullableFlags(lt.Flag | rt.Flag), Col: collationNumeric}, nil
 }
 
 func (op *opArithMul) eval(left, right eval) (eval, error) {
@@ -334,7 +334,7 @@ func (op *opArithMul) compile(c *compiler, left, right Expr) (ctype, error) {
 	}
 
 	c.asm.jumpDestination(skip1, skip2)
-	return ctype{Type: multype, Col: collationNumeric}, nil
+	return ctype{Type: multype, Flag: nullableFlags(lt.Flag | rt.Flag), Col: collationNumeric}, nil
 }
 
 func (op *opArithDiv) eval(left, right eval) (eval, error) {
@@ -604,5 +604,9 @@ func (expr *NegateExpr) compile(c *compiler) (ctype, error) {
 	}
 
 	c.asm.jumpDestination(skip)
-	return ctype{Type: neg, Col: collationNumeric}, nil
+	return ctype{Type: neg, Flag: nullableFlags(arg.Flag), Col: collationNumeric}, nil
+}
+
+func nullableFlags(flag typeFlag) typeFlag {
+	return flag & (flagNull | flagNullable)
 }

go/vt/vtgate/evalengine/expr_bit.go

@@ -298,7 +298,7 @@ func (expr *BitwiseExpr) compileBinary(c *compiler, asm_ins_bb, asm_ins_uu func(
 
 	asm_ins_uu()
 	c.asm.jumpDestination(skip1, skip2)
-	return ctype{Type: sqltypes.Uint64, Col: collationNumeric}, nil
+	return ctype{Type: sqltypes.Uint64, Flag: nullableFlags(lt.Flag | rt.Flag), Col: collationNumeric}, nil
 }
 
 func (expr *BitwiseExpr) compileShift(c *compiler, i int) (ctype, error) {
@@ -327,8 +327,8 @@ func (expr *BitwiseExpr) compileShift(c *compiler, i int) (ctype, error) {
 		return ctype{Type: sqltypes.VarBinary, Col: collationBinary}, nil
 	}
 
-	_ = c.compileToBitwiseUint64(lt, 2)
-	_ = c.compileToUint64(rt, 1)
+	lt = c.compileToBitwiseUint64(lt, 2)
+	rt = c.compileToUint64(rt, 1)
 
 	if i < 0 {
 		c.asm.BitShiftLeft_uu()
@@ -337,7 +337,7 @@ func (expr *BitwiseExpr) compileShift(c *compiler, i int) (ctype, error) {
 	}
 
 	c.asm.jumpDestination(skip1, skip2)
-	return ctype{Type: sqltypes.Uint64, Col: collationNumeric}, nil
+	return ctype{Type: sqltypes.Uint64, Flag: nullableFlags(lt.Flag | rt.Flag), Col: collationNumeric}, nil
 }
 
 func (expr *BitwiseExpr) compile(c *compiler) (ctype, error) {

go/vt/vtgate/evalengine/expr_bvar.go

@@ -91,9 +91,9 @@ func (bv *BindVariable) typeof(env *ExpressionEnv, _ []*querypb.Field) (sqltypes
 	case sqltypes.Null:
 		return sqltypes.Null, flagNull | flagNullable
 	case sqltypes.HexNum, sqltypes.HexVal:
-		return sqltypes.VarBinary, flagHex
+		return sqltypes.VarBinary, flagHex | flagNullable
 	default:
-		return tt, 0
+		return tt, flagNullable
 	}
 }
 

go/vt/vtgate/evalengine/expr_compare.go

@@ -373,11 +373,13 @@ func (expr *ComparisonExpr) compile(c *compiler) (ctype, error) {
 
 	swapped := false
 	var skip2 *jump
+	nullable := true
 
 	switch expr.Op.(type) {
 	case compareNullSafeEQ:
 		skip2 = c.asm.jumpFrom()
 		c.asm.Cmp_nullsafe(skip2)
+		nullable = false
 	default:
 		skip2 = c.compileNullCheck1r(rt)
 	}
@@ -415,6 +417,9 @@ func (expr *ComparisonExpr) compile(c *compiler) (ctype, error) {
 	}
 
 	cmptype := ctype{Type: sqltypes.Int64, Col: collationNumeric, Flag: flagIsBoolean}
+	if nullable {
+		cmptype.Flag |= nullableFlags(lt.Flag | rt.Flag)
+	}
 
 	switch expr.Op.(type) {
 	case compareEQ:
@@ -554,16 +559,17 @@ func (expr *InExpr) compile(c *compiler) (ctype, error) {
 
 	rhs := expr.Right.(TupleExpr)
 
+	var rt ctype
 	if table := expr.compileTable(lhs, rhs); table != nil {
 		c.asm.In_table(expr.Negate, table)
 	} else {
-		_, err := rhs.compile(c)
+		rt, err = rhs.compile(c)
 		if err != nil {
 			return ctype{}, err
 		}
 		c.asm.In_slow(expr.Negate)
 	}
-	return ctype{Type: sqltypes.Int64, Col: collationNumeric, Flag: flagIsBoolean}, nil
+	return ctype{Type: sqltypes.Int64, Col: collationNumeric, Flag: flagIsBoolean | (nullableFlags(lhs.Flag) | (rt.Flag & flagNullable))}, nil
 }
 
 func (l *LikeExpr) matchWildcard(left, right []byte, coll collations.ID) bool {

go/vt/vtgate/evalengine/expr_logical.go

@@ -254,7 +254,7 @@ func (expr *NotExpr) compile(c *compiler) (ctype, error) {
 		c.asm.Not_i()
 	}
 	c.asm.jumpDestination(skip)
-	return ctype{Type: sqltypes.Int64, Flag: flagNullable | flagIsBoolean, Col: collationNumeric}, nil
+	return ctype{Type: sqltypes.Int64, Flag: nullableFlags(arg.Flag) | flagIsBoolean, Col: collationNumeric}, nil
 }
 
 func (l *LogicalExpr) eval(env *ExpressionEnv) (eval, error) {
@@ -331,7 +331,7 @@ func (expr *LogicalExpr) compile(c *compiler) (ctype, error) {
 
 	c.asm.LogicalRight(expr.opname)
 	c.asm.jumpDestination(jump)
-	return ctype{Type: sqltypes.Int64, Flag: flagNullable | flagIsBoolean, Col: collationNumeric}, nil
+	return ctype{Type: sqltypes.Int64, Flag: ((lt.Flag | rt.Flag) & flagNullable) | flagIsBoolean, Col: collationNumeric}, nil
 }
 
 func intervalCompare(n, val eval) (int, bool, error) {
@@ -629,7 +629,11 @@ func (cs *CaseExpr) compile(c *compiler) (ctype, error) {
 		}
 	}
 
-	ct := ctype{Type: ta.result(), Col: ca.result()}
+	var f typeFlag
+	if ta.nullable {
+		f |= flagNullable
+	}
+	ct := ctype{Type: ta.result(), Flag: f, Col: ca.result()}
 	c.asm.CmpCase(len(cs.cases), cs.Else != nil, ct.Type, ct.Col)
 	return ct, nil
 }

go/vt/vtgate/evalengine/fn_base64.go

@@ -119,7 +119,7 @@ func (call *builtinToBase64) compile(c *compiler) (ctype, error) {
 	c.asm.Fn_TO_BASE64(t, col)
 	c.asm.jumpDestination(skip)
 
-	return ctype{Type: t, Col: col}, nil
+	return ctype{Type: t, Flag: nullableFlags(str.Flag), Col: col}, nil
 }
 
 func (call *builtinFromBase64) eval(env *ExpressionEnv) (eval, error) {
@@ -172,5 +172,5 @@ func (call *builtinFromBase64) compile(c *compiler) (ctype, error) {
 	c.asm.Fn_FROM_BASE64(t)
 	c.asm.jumpDestination(skip)
 
-	return ctype{Type: t, Col: collationBinary}, nil
+	return ctype{Type: t, Flag: nullableFlags(str.Flag), Col: collationBinary}, nil
 }

go/vt/vtgate/evalengine/fn_bit.go

@@ -68,11 +68,11 @@ func (expr *builtinBitCount) compile(c *compiler) (ctype, error) {
 	if ct.Type == sqltypes.VarBinary && !ct.isHexOrBitLiteral() {
 		c.asm.BitCount_b()
 		c.asm.jumpDestination(skip)
-		return ctype{Type: sqltypes.Int64, Col: collationBinary}, nil
+		return ctype{Type: sqltypes.Int64, Flag: nullableFlags(ct.Flag), Col: collationBinary}, nil
 	}
 
 	_ = c.compileToBitwiseUint64(ct, 1)
 	c.asm.BitCount_u()
 	c.asm.jumpDestination(skip)
-	return ctype{Type: sqltypes.Int64, Col: collationBinary}, nil
+	return ctype{Type: sqltypes.Int64, Flag: nullableFlags(ct.Flag), Col: collationBinary}, nil
 }