[SPARK-18207][SQL] Fix a compilation error due to HashExpression.doGenCode

## What changes were proposed in this pull request?

This PR avoids a compilation error due to more than 64KB Java byte code size. This error occur since  generate java code for computing a hash value for a row is too big. This PR fixes this compilation error by splitting a big code chunk into multiple methods by calling `CodegenContext.splitExpression` at `HashExpression.doGenCode`

The test case requires a calculation of hash code for a row that includes 1000 String fields. `HashExpression.doGenCode` generate a lot of Java code for this computation into one function. As a result, the size of the corresponding Java bytecode is more than 64 KB.

Generated code without this PR
````java
/* 027 */   public UnsafeRow apply(InternalRow i) {
/* 028 */     boolean isNull = false;
/* 029 */
/* 030 */     int value1 = 42;
/* 031 */
/* 032 */     boolean isNull2 = i.isNullAt(0);
/* 033 */     UTF8String value2 = isNull2 ? null : (i.getUTF8String(0));
/* 034 */     if (!isNull2) {
/* 035 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value2.getBaseObject(), value2.getBaseOffset(), value2.numBytes(), value1);
/* 036 */     }
/* 037 */
/* 038 */
/* 039 */     boolean isNull3 = i.isNullAt(1);
/* 040 */     UTF8String value3 = isNull3 ? null : (i.getUTF8String(1));
/* 041 */     if (!isNull3) {
/* 042 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value3.getBaseObject(), value3.getBaseOffset(), value3.numBytes(), value1);
/* 043 */     }
/* 044 */
/* 045 */
...
/* 7024 */
/* 7025 */     boolean isNull1001 = i.isNullAt(999);
/* 7026 */     UTF8String value1001 = isNull1001 ? null : (i.getUTF8String(999));
/* 7027 */     if (!isNull1001) {
/* 7028 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value1001.getBaseObject(), value1001.getBaseOffset(), value1001.numBytes(), value1);
/* 7029 */     }
/* 7030 */
/* 7031 */
/* 7032 */     boolean isNull1002 = i.isNullAt(1000);
/* 7033 */     UTF8String value1002 = isNull1002 ? null : (i.getUTF8String(1000));
/* 7034 */     if (!isNull1002) {
/* 7035 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value1002.getBaseObject(), value1002.getBaseOffset(), value1002.numBytes(), value1);
/* 7036 */     }
````

Generated code with this PR
````java
/* 3807 */   private void apply_249(InternalRow i) {
/* 3808 */
/* 3809 */     boolean isNull998 = i.isNullAt(996);
/* 3810 */     UTF8String value998 = isNull998 ? null : (i.getUTF8String(996));
/* 3811 */     if (!isNull998) {
/* 3812 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value998.getBaseObject(), value998.getBaseOffset(), value998.numBytes(), value1);
/* 3813 */     }
/* 3814 */
/* 3815 */     boolean isNull999 = i.isNullAt(997);
/* 3816 */     UTF8String value999 = isNull999 ? null : (i.getUTF8String(997));
/* 3817 */     if (!isNull999) {
/* 3818 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value999.getBaseObject(), value999.getBaseOffset(), value999.numBytes(), value1);
/* 3819 */     }
/* 3820 */
/* 3821 */     boolean isNull1000 = i.isNullAt(998);
/* 3822 */     UTF8String value1000 = isNull1000 ? null : (i.getUTF8String(998));
/* 3823 */     if (!isNull1000) {
/* 3824 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value1000.getBaseObject(), value1000.getBaseOffset(), value1000.numBytes(), value1);
/* 3825 */     }
/* 3826 */
/* 3827 */     boolean isNull1001 = i.isNullAt(999);
/* 3828 */     UTF8String value1001 = isNull1001 ? null : (i.getUTF8String(999));
/* 3829 */     if (!isNull1001) {
/* 3830 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value1001.getBaseObject(), value1001.getBaseOffset(), value1001.numBytes(), value1);
/* 3831 */     }
/* 3832 */
/* 3833 */   }
/* 3834 */
...
/* 4532 */   private void apply_0(InternalRow i) {
/* 4533 */
/* 4534 */     boolean isNull2 = i.isNullAt(0);
/* 4535 */     UTF8String value2 = isNull2 ? null : (i.getUTF8String(0));
/* 4536 */     if (!isNull2) {
/* 4537 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value2.getBaseObject(), value2.getBaseOffset(), value2.numBytes(), value1);
/* 4538 */     }
/* 4539 */
/* 4540 */     boolean isNull3 = i.isNullAt(1);
/* 4541 */     UTF8String value3 = isNull3 ? null : (i.getUTF8String(1));
/* 4542 */     if (!isNull3) {
/* 4543 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value3.getBaseObject(), value3.getBaseOffset(), value3.numBytes(), value1);
/* 4544 */     }
/* 4545 */
/* 4546 */     boolean isNull4 = i.isNullAt(2);
/* 4547 */     UTF8String value4 = isNull4 ? null : (i.getUTF8String(2));
/* 4548 */     if (!isNull4) {
/* 4549 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value4.getBaseObject(), value4.getBaseOffset(), value4.numBytes(), value1);
/* 4550 */     }
/* 4551 */
/* 4552 */     boolean isNull5 = i.isNullAt(3);
/* 4553 */     UTF8String value5 = isNull5 ? null : (i.getUTF8String(3));
/* 4554 */     if (!isNull5) {
/* 4555 */       value1 = org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeBytes(value5.getBaseObject(), value5.getBaseOffset(), value5.numBytes(), value1);
/* 4556 */     }
/* 4557 */
/* 4558 */   }
...
/* 7344 */   public UnsafeRow apply(InternalRow i) {
/* 7345 */     boolean isNull = false;
/* 7346 */
/* 7347 */     value1 = 42;
/* 7348 */     apply_0(i);
/* 7349 */     apply_1(i);
...
/* 7596 */     apply_248(i);
/* 7597 */     apply_249(i);
/* 7598 */     apply_250(i);
/* 7599 */     apply_251(i);
...
````

## How was this patch tested?

Add a new test in `DataFrameSuite`

Author: Kazuaki Ishizaki <ishizaki@jp.ibm.com>

Closes #15745 from kiszk/SPARK-18207.

0 files changed, 0 insertions, 0 deletions