[IMPALA-4008] Generate codegen module without operator/query-specific constants

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.7.0
• Fix Version/s: Impala 2.8.0
• Component/s: Backend
• Labels: codegen
• Target Version: Product Backlog
• Assignee: Michael Ho
• Reporter: Tim Armstrong
• Created: 23/Aug/16 17:24
• Updated: 28/Sep/16 23:29
• Resolved: 28/Sep/16 23:29

Description

Codegen'd code currently has certain operator-specific constants baked into it. E.g. the HashTableCtx address. This limits flexibility if we want to e.g. cache codegen'd objects or share codegen'd objects between different fragment instances.

I attached a proof-of-concept codegen caching implementation based on the LLVM bitcode generated by the operators. It's interesting because a cache hit implies that the codegen'd module content was identical.

Issue Links

• blocks: IMPALA-4080 Share codegen work between fragment instances