expression: fix float64 overflow check in plus/minus real function (#…

…24179) (#26724)
pingcap · Sep 3, 2021 · a58a482 · a58a482
1 parent 7bdcf69
commit a58a482
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Showing 4 changed files with 20 additions and 4 deletions.
diff --git a/expression/builtin_arithmetic.go b/expression/builtin_arithmetic.go
@@ -23,6 +23,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
+	math2 "github.com/pingcap/tidb/util/math"
 	"github.com/pingcap/tipb/go-tipb"
 )
 
@@ -293,7 +294,7 @@ func (s *builtinArithmeticPlusRealSig) evalReal(row chunk.Row) (float64, bool, e
 	if isLHSNull || isRHSNull {
 		return 0, true, nil
 	}
-	if (a > 0 && b > math.MaxFloat64-a) || (a < 0 && b < -math.MaxFloat64-a) {
+	if !math2.IsFinite(a + b) {
 		return 0, true, types.ErrOverflow.GenWithStackByArgs("DOUBLE", fmt.Sprintf("(%s + %s)", s.args[0].String(), s.args[1].String()))
 	}
 	return a + b, false, nil
@@ -362,7 +363,7 @@ func (s *builtinArithmeticMinusRealSig) evalReal(row chunk.Row) (float64, bool,
 	if isNull || err != nil {
 		return 0, isNull, err
 	}
-	if (a > 0 && -b > math.MaxFloat64-a) || (a < 0 && -b < -math.MaxFloat64-a) {
+	if !math2.IsFinite(a - b) {
 		return 0, true, types.ErrOverflow.GenWithStackByArgs("DOUBLE", fmt.Sprintf("(%s - %s)", s.args[0].String(), s.args[1].String()))
 	}
 	return a - b, false, nil

diff --git a/expression/builtin_arithmetic_vec.go b/expression/builtin_arithmetic_vec.go
@@ -21,6 +21,7 @@ import (
 	"github.com/pingcap/parser/terror"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
+	math2 "github.com/pingcap/tidb/util/math"
 )
 
 func (b *builtinArithmeticMultiplyRealSig) vectorized() bool {
@@ -276,7 +277,7 @@ func (b *builtinArithmeticMinusRealSig) vecEvalReal(input *chunk.Chunk, result *
 		if result.IsNull(i) {
 			continue
 		}
-		if (x[i] > 0 && -y[i] > math.MaxFloat64-x[i]) || (x[i] < 0 && -y[i] < -math.MaxFloat64-x[i]) {
+		if !math2.IsFinite(x[i] - y[i]) {
 			return types.ErrOverflow.GenWithStackByArgs("DOUBLE", fmt.Sprintf("(%s - %s)", b.args[0].String(), b.args[1].String()))
 		}
 		x[i] = x[i] - y[i]
@@ -475,7 +476,7 @@ func (b *builtinArithmeticPlusRealSig) vecEvalReal(input *chunk.Chunk, result *c
 		if result.IsNull(i) {
 			continue
 		}
-		if (x[i] > 0 && y[i] > math.MaxFloat64-x[i]) || (x[i] < 0 && y[i] < -math.MaxFloat64-x[i]) {
+		if !math2.IsFinite(x[i] + y[i]) {
 			return types.ErrOverflow.GenWithStackByArgs("DOUBLE", fmt.Sprintf("(%s + %s)", b.args[0].String(), b.args[1].String()))
 		}
 		x[i] = x[i] + y[i]

diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -9161,6 +9161,15 @@ func (s *testIntegrationSuite) TestIssue23889(c *C) {
 		testkit.Rows("<nil>", "0"))
 }
 
+func (s *testIntegrationSuite) TestFloat64Inf(c *C) {
+	defer s.cleanEnv(c)
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustQuery("select '1e800' + 1e100;").Check(
+		testkit.Rows("179769313486231570000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"))
+	tk.MustQuery("select '-1e800' - 1e100;").Check(
+		testkit.Rows("-179769313486231570000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"))
+}
+
 func (s *testIntegrationSuite2) TestIssue25591(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 

diff --git a/util/math/math.go b/util/math/math.go
@@ -48,3 +48,8 @@ func StrLenOfInt64Fast(x int64) int {
 	}
 	return size + StrLenOfUint64Fast(uint64(Abs(x)))
 }
+
+// IsFinite reports whether f is neither NaN nor an infinity.
+func IsFinite(f float64) bool {
+	return !math.IsNaN(f - f)
+}