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libFirm, postgres, JIT compilation and forth
May 27, 2016
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 1 / 12
libFirm
Compiler library providing IR, optimiziations and code generatorsResearch project at ipd.kit.edu, LGPL (lib�rm), GPL (frontends)
libFirm
cparser
Firm
ARM(alpha)
AMD64(beta)
SPARC
IA32optimizations
Java
X10
brainfuck
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 2 / 12
Postgres is in need of JIT compilation
Query plans (trees) are interpreted by the executor
By calling function pointers in plan nodesThe invoked functions themselves again invoke function pointers
To evaluate expression trees
To evaluate operators
For access method strategy functions
Some calls via funcall API ; even more overhead
PL/PgSQL is evaluated basically the same
E.g. comparison (int > int) may require thousands of instructionswhere it optimally would be only a few
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 3 / 12
Same algorithm implemented in C and PL/PgSQL
psql=> select proname, levenshtein(proname, 'levenstein')
from pg_proc order by 2 limit 1;
proname | levenshtein
-------------+-------------
levenshtein | 1
Time: 2.498 ms
psql=> select proname, plpgsql_lev(proname, 'levenstein')
from pg_proc order by 2 limit 1;
proname | plpgsql_lev
-------------+-------------
levenshtein | 1
Time: 837.526 ms
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 4 / 12
Competing work
Vitesse Data is selling a JIT-compiling postgres using LLVM
Unpublished work by ISP RAS using LLVM in postgres
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 5 / 12
JIT compilation with libFirm
Nobody's done JIT with libFirm before
Wrote a JIT forth system to study feasibility
Excursion: forth systems
Primitve, but usable (unlike brainfuck)
Read words which operate on a parameter stack
> 1 1 + .
2
Language can be extended with new words
> : foo 1 1 + . ;
> foo
2
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 6 / 12
Firmforth recipe
1 Keep IR for C-implemented words around
2 Model function calls in FIRM instead of building arrays of pointers tointerpret
3 Run libFirm-provided optimizations
4 Run libFirm code generator
5 Invoke assembler/linker
6 Link the shared object into the running program via dlopen()
7 Look up new function via dlsym() and put it in dictionary
8 Keep IR of new word around
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 7 / 12
Firmforth graphically
firmforth.c
cparser+libFirm
cc
firmforth.irfirmforth+libFirm
firmforth
foo_constructed.vcgfoo_optimized.vcg
debug
foo.s
: foo1 1 + . ;
assembler+linkerfoo.so
dlopen()
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 8 / 12
Firmforth results
Got it working without dirty hacks
Developers were extremely responsive (#�rm on freenode)
Minor changes required to libFirm (went upstream)
Benchmark:
: fibonacci
dup 0= if else
dup 1 = if else
1 - dup fibonacci
swap 1 - fibonacci +
then
then ;
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 9 / 12
Benchmark results
�rmforth has speedups of
5.5 over stubforth
Its interpreter uses computed gotos instead of calls
2.6 over GNU gforth-fast
Fastest C-forth known to me (and #forth on freenode)Heavily �ne optimized
17.6 over a non-optimizing �rmforth
I.e., performing a call for each word
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 10 / 12
Future work
1 Apply proven recipe for the PostgreSQL executor
maybe in the shape of an extensionprepare select ... as foo; pg_jit('foo');
2 Further extend JIT infrastructure
Formulate things beyond callsExpressionsPL/PgSQL
3 Implement additional optimizations on the IR
E.g. vectorization
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 11 / 12
References
http://pp.ipd.kit.edu/firm/
https://github.com/anse1/firmforth
https://www.postgresql.org/message-id/87lks946bc.fsf@
gate450.dyndns.org
http://vitessedata.com/vitesse-db
https://www.postgresql.org/message-id/5733405A.7060502@
postgrespro.ru
[email protected] libFirm, postgres, JIT compilation and forth May 27, 2016 12 / 12
