Virtual tuple table slots never need tuple deforming. Therefore, if we
know at expression compilation time, that a certain slot will always
be virtual, there's no need to create a tuple deforming routine for
it.
Author: Andres Freund
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de
Previously this information was computed when JIT compiling an
expression. But the information is useful for assertions in the
non-JIT case too (for assertions), therefore it makes sense to move
it.
This will, in a followup commit, allow to treat different slot types
differently. E.g. for virtual slots there's no need to generate a JIT
function to deform the slot.
Author: Andres Freund
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de
This mainly de-duplicates code. As evaluating a system variable isn't
the hottest path and the current inline implementation ends up calling
out to an external function anyway, this is OK from a performance POV.
The main motivation for de-duplicating is the upcoming slot
abstraction work, after which there's not guaranteed to be a HeapTuple
backing the slot.
Author: Andres Freund, Amit Khandekar
Discussion: https://postgr.es/m/20181105210039.hh4vvi4vwoq5ba2q@alap3.anarazel.de
This only became a problem with 4c640f4f38, which didn't synchronize
the value agg_strict_input_check.nargs is set to, with the guard
condition for emitting the operation.
Besides such instructions being unnecessary overhead, currently the
LLVM JIT provider doesn't support them. It seems more sensible to
avoid generating such instruction than supporting them. Add assertions
to make it easier to debug a potential further occurance.
Discussion: https://postgr.es/m/2a505161-2727-2473-7c46-591ed108ac52@email.cz
Backpatch: 11-, like 4c640f4f38.
There's several reasons for this change:
1) It reduces the total size of TupleTableSlot / reduces alignment
padding, making the commonly accessed members fit into a single
cacheline (but we currently do not force proper alignment, so
that's not yet guaranteed to be helpful)
2) Combining the booleans into a flag allows to combine read/writes
from memory.
3) With the upcoming slot abstraction changes, it allows to have core
and extended flags, in a memory efficient way.
Author: Ashutosh Bapat and Andres Freund
Discussion: https://postgr.es/m/20180220224318.gw4oe5jadhpmcdnm@alap3.anarazel.de
Previously it was an int / 4 bytes. The maximum number of attributes
in a tuple is restricted by the maximum value Var->varattno, which is
an AttrNumber/int16. Hence use the same data type for
TupleTableSlot->tts_nvalid.
Author: Ashutosh Bapat
Discussion: https://postgr.es/m/20180220224318.gw4oe5jadhpmcdnm@alap3.anarazel.de
Previously, when using parallel query, EXPLAIN (ANALYZE)'s JIT
compilation timings did not include the overhead from doing so on the
workers. Fix that.
We do so by simply aggregating the cost of doing JIT compilation on
workers and the leader together. Arguably that's not quite accurate,
because the total time spend doing so is spent in parallel - but it's
hard to do much better. For additional detail, when VERBOSE is
specified, the stats for workers are displayed separately.
Author: Amit Khandekar and Andres Freund
Discussion: https://postgr.es/m/CAJ3gD9eLrz51RK_gTkod+71iDcjpB_N8eC6vU2AW-VicsAERpQ@mail.gmail.com
Backpatch: 11-
The JIT compiled implementation missed maintaining
AggState->{current_set,curaggcontext}. That could lead to trouble
because the transition value could be allocated in the wrong context.
Reported-By: Rushabh Lathia
Diagnosed-By: Dmitry Dolgov
Author: Dmitry Dolgov, with minor changes by me
Discussion: https://postgr.es/m/CAGPqQf165-=+Drw3Voim7M5EjHT1zwPF9BQRjLFQzCzYnNZEiQ@mail.gmail.com
Backpatch: 11-, where JIT compilation support was added
Tom's earlier commit in 41c912cad1 didn't update a few cases that
are only encountered with the non-standard --with-llvm config
flag. Additionally there's also one case that appears to be a
deficiency in gcc's (up to trunk as of a few days ago) detection of
"fallthrough" comments - changing the placement slightly fixes that.
Author: Andres Freund
Discussion: https://postgr.es/m/20180502003239.wfnqu7ekz7j7imm4@alap3.anarazel.de
Performing JIT compilation for deforming gains performance benefits
over unJITed deforming from compile-time knowledge of the tuple
descriptor. Fixed column widths, NOT NULLness, etc can be taken
advantage of.
Right now the JITed deforming is only used when deforming tuples as
part of expression evaluation (and obviously only if the descriptor is
known). It's likely to be beneficial in other cases, too.
By default tuple deforming is JITed whenever an expression is JIT
compiled. There's a separate boolean GUC controlling it, but that's
expected to be primarily useful for development and benchmarking.
Docs will follow in a later commit containing docs for the whole JIT
feature.
Author: Andres Freund
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de
The LLVM JIT provider uses clang to synchronize types between normal C
code and runtime generated code. Clang represents stdbool.h style
booleans in return values & parameters differently from booleans
stored in variables.
Thus the expression compilation code from 2a0faed9d needs to be
adapted to 9a95a77d9. Instead of hardcoding i8 as the type for
booleans (which already was wrong on some edge case platforms!), use
postgres' notion of a boolean as used for storage and for parameters.
Per buildfarm animal xenodermus.
Author: Andres Freund
In addition to the interpretation of expressions (which back
evaluation of WHERE clauses, target list projection, aggregates
transition values etc) support compiling expressions to native code,
using the infrastructure added in earlier commits.
To avoid duplicating a lot of code, only support emitting code for
cases that are likely to be performance critical. For expression steps
that aren't deemed that, use the existing interpreter.
The generated code isn't great - some architectural changes are
required to address that. But this already yields a significant
speedup for some analytics queries, particularly with WHERE clauses
filtering a lot, or computing multiple aggregates.
Author: Andres Freund
Tested-By: Thomas Munro
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de
Disable JITing for VALUES() nodes.
VALUES() nodes are only ever executed once. This is primarily helpful
for debugging, when forcing JITing even for cheap queries.
Author: Andres Freund
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de
Bruce Momjian
Andres Freund
Tom Lane