[GLUTEN-9178][CH] Fix cse in aggregate operator not working

[loneylee]

What changes were proposed in this pull request?

(Please fill in changes proposed in this fix)

(Fixes: #9178)

How was this patch tested?

Test by ut

[github-actions]

#9178

[github-actions]

Run Gluten Clickhouse CI on x86

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• backends-clickhouse/src/main/scala/org/apache/gluten/extension/CommonSubexpressionEliminateRule.scala: Language not supported
• backends-clickhouse/src/test/scala/org/apache/gluten/execution/GlutenFunctionValidateSuite.scala: Language not supported

[github-actions]

Run Gluten Clickhouse CI on x86

[loneylee]

@CodiumAI-Agent /improve

[QodoAI-Agent]

PR Code Suggestions ✨

Latest suggestions up to 3f9799e

Category	Suggestion	Impact
Possible issue	Validate children list length Before accessing the first element of aggFunc.children, ensure the list is non-empty to avoid runtime exceptions. backends-clickhouse/src/test/scala/org/apache/gluten/execution/GlutenFunctionValidateSuite.scala [841-843] .map(expr => expr.asInstanceOf[AggregateExpression].aggregateFunction) -.filter(aggFunc => aggFunc.children.head.isInstanceOf[AttributeReference]) +.filter(aggFunc => aggFunc.children.nonEmpty && aggFunc.children.head.isInstanceOf[AttributeReference]) .map(aggFunc => aggFunc.children.head.asInstanceOf[AttributeReference].name) Suggestion importance[1-10]: 6 __ Why: The suggestion improves safety by checking that aggFunc.children is non-empty before accessing head, which can prevent potential runtime exceptions; however, its impact is moderate as it only adds a defensive check in a specific context.	Low

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Previous suggestions

Suggestions up to commit 3f9799e

Category	Suggestion	Impact
Possible issue	Guard head access safely Safely access the first child by checking its existence to avoid potential exceptions when the children list is empty. backends-clickhouse/src/test/scala/org/apache/gluten/execution/GlutenFunctionValidateSuite.scala [844] -.map(aggFunc => aggFunc.children.head.asInstanceOf[AttributeReference].name) +.flatMap { aggFunc => + aggFunc.children.headOption match { + case Some(attr: AttributeReference) => Some(attr.name) + case _ => None + } +} Suggestion importance[1-10]: 5 __ Why: While adding a safety check for head access can prevent potential runtime exceptions, the context already filters for valid AttributeReference instances, making the improvement only moderately beneficial.	Low

[loneylee]

@taiyang-li cc

[taiyang-li]

LGTM