ilike function may cause data race for non-constant pattern

[lcwangchao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

We can see that in line 201, the pattern is constructed and set builtinIlikeSig.pattern

tidb/pkg/expression/builtin_ilike_vec.go

Lines 200 to 203 in 5c279d8

	if !b.isMemorizedPattern {
	b.pattern = collate.ConvertAndGetBinCollation(b.collation).Pattern()
	return b.ilikeWithoutMemorization(params, rowNum, escape, result)
	}

contVec and vecVec uses builtinlikeSIg.pattern directly:

tidb/pkg/expression/builtin_ilike_vec.go

Lines 137 to 150 in 5c279d8

	func (b *builtinIlikeSig) constVec(expr string, param *funcParam, rowNum int, escape int64, result *chunk.Column) error {
	result.ResizeInt64(rowNum, false)
	result.MergeNulls(param.getCol())
	i64s := result.Int64s()
	for i := 0; i < rowNum; i++ {
	if result.IsNull(i) {
	continue
	}
	b.pattern.Compile(param.getStringVal(i), byte(escape))
	match := b.pattern.DoMatch(expr)
	i64s[i] = boolToInt64(match)
	}
	return nil
	}

If expression is evaluated in concurrency, it may cause data race

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiDB version? (Required)