pgsql: Evaluate arguments of correlated SubPlans in the referencing Exp

Evaluate arguments of correlated SubPlans in the referencing ExprState

Until now we generated an ExprState for each parameter to a SubPlan and
evaluated them one-by-one ExecScanSubPlan. That's sub-optimal as creating lots
of small ExprStates
a) makes JIT compilation more expensive
b) wastes memory
c) is a bit slower to execute

This commit arranges to evaluate parameters to a SubPlan as part of the
ExprState referencing a SubPlan, using the new EEOP_PARAM_SET expression
step. We emit one EEOP_PARAM_SET for each argument to a subplan, just before
the EEOP_SUBPLAN step.

It likely is worth using EEOP_PARAM_SET in other places as well, e.g. for
SubPlan outputs, nestloop parameters and - more ambitiously - to get rid of
ExprContext->domainValue/caseValue/ecxt_agg*. But that's for later.

Author: Andres Freund <andres(at)anarazel(dot)de>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Alena Rybakina <lena(dot)ribackina(at)yandex(dot)ru>
Discussion: https://postgr.es/m/20230225214401.346ancgjqc3zmvek@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a7f107df2b700c859e4d9ad2ca66b07a465d6223

Modified Files
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src/backend/executor/execExpr.c | 103 +++++++++++++++++++++++-----------
src/backend/executor/execExprInterp.c | 26 +++++++++
src/backend/executor/execProcnode.c | 5 ++
src/backend/executor/nodeSubplan.c | 29 ++++------
src/backend/jit/llvm/llvmjit_expr.c | 6 ++
src/backend/jit/llvm/llvmjit_types.c | 1 +
src/include/executor/execExpr.h | 6 +-
src/include/nodes/execnodes.h | 1 -
8 files changed, 125 insertions(+), 52 deletions(-)