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Revision 1.3 by root, Mon Mar 13 16:59:36 2006 UTC vs.
Revision 1.4 by root, Sat Feb 21 08:27:38 2009 UTC

… …
5 use Faster; 5 use Faster;
6 6
7 perl -MFaster ... 7 perl -MFaster ...
8 8
9DESCRIPTION 9DESCRIPTION
10 This module implements a very simple-minded JIT. It works by more or 10 This module implements a very simple-minded "JIT" (or actually AIT,
11 less translating every function it sees into a C program, compiling it 11 ahead of time compiler). It works by more or less translating every
12 and then replacing the function by the compiled code. 12 function it sees into a C program, compiling it and then replacing the
13 function by the compiled code.
13 14
14 As a result, startup times are immense, as every function might lead to 15 As a result, startup times are immense, as every function might lead to
15 a full-blown compilation. 16 a full-blown compilation.
16 17
17 The speed improvements are also not great, you can expect 20% or so on 18 The speed improvements are also not great, you can expect 20% or so on
18 average, for code that runs very often. 19 average, for code that runs very often. The reason for this is that data
20 handling is mostly being done by the same old code, it just gets called
21 a bit faster. Regexes and string operations won't get faster. Airhtmetic
22 doresn't become any faster. Just the operands and other stuff is put on
23 the stack faster, and the opcodes themselves have a bit less overhead.
19 24
20 Faster is in the early stages of development. Due to its design its 25 Faster is in the early stages of development. Due to its design its
21 relatively safe to use (it will either work or simply slowdown the 26 relatively safe to use (it will either work or simply slowdown the
22 program immensely, but rarely cause bugs). 27 program immensely, but rarely cause bugs).
23 28
29 More intelligent algorithms (loop optimisation, type inference) could
30 improve that easily, but requires a much more elaborate presentation and
31 optimiser than what is in place. There are no plans to improve Faster in
32 this way, yet, but it would provide a reasonably good place to start.
33
24 Usage is very easy, just "use Faster" and every function called from 34 Usage is very easy, just "use Faster" and every function called from
25 then on will be compiled. 35 then on will be compiled.
26 36
27 Right now, Faster will leave lots of *.c, *.o and *.so files in your 37 Right now, Faster can leave lots of *.c and *.so files in your
28 $FASTER_CACHEDIR (by default $HOME/.perl-faster-cache), and it will even 38 $FASTER_CACHEDIR (by default $HOME/.perl-faster-cache), and it will even
29 create those temporary files in an insecure manner, so watch out. 39 create those temporary files in an insecure manner, so watch out.
30 40
31ENVIRONMENT VARIABLES 41ENVIRONMENT VARIABLES
32 The following environment variables influence the behaviour of Faster: 42 The following environment variables influence the behaviour of Faster:
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37 compiled, 3 outputs the cache directory and 10 outputs information 47 compiled, 3 outputs the cache directory and 10 outputs information
38 on which perl function is compiled into which shared object. 48 on which perl function is compiled into which shared object.
39 49
40 FASTER_DEBUG 50 FASTER_DEBUG
41 Add debugging code when set to values higher than 0. Currently, this 51 Add debugging code when set to values higher than 0. Currently, this
42 adds 1-3 "assert"'s per perl op, to ensure that opcode order and C 52 adds 1-3 "assert"'s per perl op (FASTER_DEBUG > 1), to ensure that
43 execution order are compatible. 53 opcode order and C execution order are compatible.
44 54
45 FASTER_CACHE 55 FASTER_CACHE
46 Set a persistent cache directory that caches compiled code 56 Set a persistent cache directory that caches compiled code
47 fragments. The default is "$HOME/.perl-faster-cache" if "HOME" is 57 fragments. The default is "$HOME/.perl-faster-cache" if "HOME" is
48 set and a temporary directory otherwise. 58 set and a temporary directory otherwise.
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70 executed function as soon as they are being encountered during 80 executed function as soon as they are being encountered during
71 execution. 81 execution.
72 82
73 goto 83 goto
74 next, redo (but not well-behaved last's) 84 next, redo (but not well-behaved last's)
85 labels, if used
75 eval 86 eval
76 require 87 require
77 any use of formats 88 any use of formats
78 .., ... (flipflop operators) 89 .., ... (flipflop operators)
79 90

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