From a1a308bd7ed914367eb24f884ecffff88d608555 Mon Sep 17 00:00:00 2001
From: tsthght <781181214@qq.com>
Date: Wed, 18 Sep 2019 21:59:46 +0800
Subject: [PATCH] expression: implement vectorized evaluation for builtinPowSig
 (#12242)

---
 expression/bench_test.go            | 19 +++++++++++++++
 expression/builtin_math_vec.go      | 36 +++++++++++++++++++++++++++++
 expression/builtin_math_vec_test.go |  3 +++
 3 files changed, 58 insertions(+)

diff --git a/expression/bench_test.go b/expression/bench_test.go
index abd3eb5adb7b6..e36c43be1c742 100644
--- a/expression/bench_test.go
+++ b/expression/bench_test.go
@@ -248,6 +248,25 @@ func (g *defaultGener) gen() interface{} {
 	return nil
 }
 
+// rangeRealGener is used to generate float64 items in [begin, end].
+type rangeRealGener struct {
+	begin float64
+	end   float64
+
+	nullRation float64
+}
+
+func (g *rangeRealGener) gen() interface{} {
+	if rand.Float64() < g.nullRation {
+		return nil
+	}
+	if g.end <= g.begin {
+		g.begin = -100
+		g.end = 100
+	}
+	return rand.Float64()*(g.end-g.begin) + g.begin
+}
+
 // rangeInt64Gener is used to generate int64 items in [begin, end).
 type rangeInt64Gener struct {
 	begin int
diff --git a/expression/builtin_math_vec.go b/expression/builtin_math_vec.go
index f9cfcd715fc4f..e9a0c0feb1425 100644
--- a/expression/builtin_math_vec.go
+++ b/expression/builtin_math_vec.go
@@ -311,3 +311,39 @@ func (b *builtinRoundDecSig) vecEvalDecimal(input *chunk.Chunk, result *chunk.Co
 func (b *builtinRoundDecSig) vectorized() bool {
 	return true
 }
+
+func (b *builtinPowSig) vecEvalReal(input *chunk.Chunk, result *chunk.Column) error {
+	n := input.NumRows()
+	buf1, err := b.bufAllocator.get(types.ETReal, n)
+	if err != nil {
+		return err
+	}
+	defer b.bufAllocator.put(buf1)
+	if err := b.args[0].VecEvalReal(b.ctx, input, buf1); err != nil {
+		return err
+	}
+
+	if err := b.args[1].VecEvalReal(b.ctx, input, result); err != nil {
+		return err
+	}
+
+	x := buf1.Float64s()
+	y := result.Float64s()
+	result.MergeNulls(buf1)
+	f64s := result.Float64s()
+	for i := 0; i < n; i++ {
+		if result.IsNull(i) {
+			continue
+		}
+		power := math.Pow(x[i], y[i])
+		if math.IsInf(power, -1) || math.IsInf(power, 1) || math.IsNaN(power) {
+			return types.ErrOverflow.GenWithStackByArgs("DOUBLE", fmt.Sprintf("pow(%s, %s)", strconv.FormatFloat(x[i], 'f', -1, 64), strconv.FormatFloat(y[i], 'f', -1, 64)))
+		}
+		f64s[i] = power
+	}
+	return nil
+}
+
+func (b *builtinPowSig) vectorized() bool {
+	return true
+}
diff --git a/expression/builtin_math_vec_test.go b/expression/builtin_math_vec_test.go
index a2b90177f2f21..39151c58b41ea 100644
--- a/expression/builtin_math_vec_test.go
+++ b/expression/builtin_math_vec_test.go
@@ -61,6 +61,9 @@ var vecBuiltinMathCases = map[string][]vecExprBenchCase{
 	ast.Round: {
 		{types.ETDecimal, []types.EvalType{types.ETDecimal}, nil},
 	},
+	ast.Pow: {
+		{types.ETReal, []types.EvalType{types.ETReal, types.ETReal}, []dataGenerator{&rangeRealGener{0, 10, 0.5}, &rangeRealGener{0, 100, 0.5}}},
+	},
 }
 
 func (s *testEvaluatorSuite) TestVectorizedBuiltinMathEvalOneVec(c *C) {