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This patch fixes two issues around handling of constant expr args. The patches are combined because they touch some of the same code and depend on some of the same memory management cleanup. First, it fixes IMPALA-2379, where constant expr args were not visible to UDAFs. The issue is that the input exprs need to be opened before calling the UDAF Init() function. Second, it avoids overhead from repeated evaluation of constant arguments for ScalarFnCall expressions on both the codegen'd and interpreted paths. A common example is an IN predicate with a long list of constant values. The interpreted path was inefficient because it always evaluated all children expressions. Instead in this patch constant args are evaluated once and cached. The memory management of the AnyVal* objects was somewhat nebulous - adjusted it so that they're allocated from ExprContext::mem_pool_, which has the correct lifetime. The codegen'd path was inefficient only with varargs - with fixed arguments the LLVM optimiser is able to infer after inlining that the expressions are constant and remove all evaluation. However, for varargs it stores the vararg values into a heap-allocated buffer. The LLVM optimiser is unable to remove these stores because they have a side-effect that is visible to code outside the function. The codegen'd path is improved by evaluating varargs into an automatic buffer that can be optimised out. We also make a small related change to bake the string constants into the codegen'd code. Testing: Ran exhaustive build. Added regression test for IMPALA-2379 and MemPool test for aligned allocation. Added a test for in predicates with constant strings. Perf: Added a targeted query that demonstrates the improvement. Also manually validated the non-codegend perf. Also ran TPC-H and targeted perf queries locally - didn't see any significant changes. +--------------------+-------------------------------+-----------------------+--------+-------------+------------+-----------+----------------+-------------+-------+ | Workload | Query | File Format | Avg(s) | Base Avg(s) | Delta(Avg) | StdDev(%) | Base StdDev(%) | Num Clients | Iters | +--------------------+-------------------------------+-----------------------+--------+-------------+------------+-----------+----------------+-------------+-------+ | TARGETED-PERF(_20) | primitive_filter_in_predicate | parquet / none / none | 1.19 | 9.82 | I -87.85% | 3.82% | 0.71% | 1 | 10 | +--------------------+-------------------------------+-----------------------+--------+-------------+------------+-----------+----------------+-------------+-------+ (I) Improvement: TARGETED-PERF(_20) primitive_filter_in_predicate [parquet / none / none] (9.82s -> 1.19s [-87.85%]) +--------------+------------+----------+----------+------------+-----------+----------+----------+------------+--------+--------+-----------+ | Operator | % of Query | Avg | Base Avg | Delta(Avg) | StdDev(%) | Max | Base Max | Delta(Max) | #Hosts | #Rows | Est #Rows | +--------------+------------+----------+----------+------------+-----------+----------+----------+------------+--------+--------+-----------+ | 01:AGGREGATE | 14.39% | 155.88ms | 214.61ms | -27.37% | 2.68% | 163.38ms | 227.53ms | -28.19% | 1 | 1 | 1 | | 00:SCAN HDFS | 85.60% | 927.46ms | 9.43s | -90.16% | 4.49% | 1.01s | 9.50s | -89.42% | 1 | 13.77K | 14.05K | +--------------+------------+----------+----------+------------+-----------+----------+----------+------------+--------+--------+-----------+ Change-Id: I45c3ed8c9d7a61e94a9b9d6c316e8a53d9ff6c24 Reviewed-on: http://gerrit.cloudera.org:8080/4838 Reviewed-by: Tim Armstrong <tarmstrong@cloudera.com> Tested-by: Internal Jenkins