[yoshimi] Re: Techie stuff
- From: Will Godfrey <willgodfrey@xxxxxxxxxxxxxxx>
- To: yoshimi@xxxxxxxxxxxxx
- Date: Thu, 14 Jun 2018 22:19:54 +0100
On Thu, 14 Jun 2018 14:43:32 +0200
Ichthyostega <prg@xxxxxxxxxxxxxxx> wrote:
On 13.06.2018 18:48, Jesper Lloyd wrote:
I see no fundamental errors in what is written, but I would be cautious about
the jump table assumptions (as regards both generated instructions and the
actual performance) without thorough benchmarking.
...which just reinforces my impression, that -- on the long run, not right now,
we should look into building some infrastructure for automated acceptance
testing. We discussed that a bit on LAC, and I am fully aware that this is
non trivial. Yet some parts of the yoshimi code base are really tricky since
we tend to press things to the limit.
-- Hermann
Indeed, and I quite agree with this. As ever, it's all a matter of time and
priorities.
Incidentally, I recoded the switch timing tests I did way back when. The
results are interesting. It needs about 40 cases to show a difference between
sparse and packed ones, and 80 really shows the difference, and that the
timings are more stable. Mind you, that's compiling with no optimisations, and
making the cases all do *something* to stop the compiler optimising them out.
I've attached a copy of the code.
Following up on Jesper's concern...
Originally we had a globals.h file with pretty much nothing but #defines. Cal,
moved all those into CMakeLists, and since then a lot more have been added
(mostly by me).
I'm wondering if that should be reversed, with a re-check on which really need
to be global in scope, and whether some would be better as static const.
Also, I think this would be the place to put enums to take the place of magic
numbers. Most of these are applicable in at least three places.
As ever, thoughts welcome.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
/*
timings
*/
#include <stdio.h>
#include <sys/time.h>
# include <iostream>
using namespace std;
int packed(int test)
{
struct timeval tv1, tv2;
int result = 90;
gettimeofday(&tv1, NULL);
for (int i = 0; i < 2000; ++i) // takes about 4 seconds
{
for (int j = 0; j < 1000000; ++j)
{
switch (test)
{
case 0:
result += 5;
break;
case 1:
result += 2;
break;
case 2:
result += 7;
break;
case 3:
result -= 5;
break;
case 4:
result += 20;
break;
case 5:
result -= 35;
break;
case 6:
result += 1;
break;
case 7:
result = 555;
break;
case 8:
result -= 7;
break;
case 9:
result -= 33;
break;
case 10:
result = 28;
break;
case 11:
result = 59;
break;
case 12:
result += 16;
break;
case 13:
result += 4;
break;
case 14:
result -= 33;
break;
case 15:
result = 19;
break;
case 16:
result += 16;
break;
case 17:
result += 4;
break;
case 18:
result -= 33;
break;
case 19:
result = 19;
break;
case 20:
result += 5;
break;
case 21:
result += 2;
break;
case 22:
result += 7;
break;
case 23:
result -= 5;
break;
case 24:
result += 20;
break;
case 25:
result -= 35;
break;
case 26:
result += 1;
break;
case 27:
result = 555;
break;
case 28:
result -= 7;
break;
case 29:
result -= 33;
break;
case 30:
result = 28;
break;
case 31:
result = 59;
break;
case 32:
result += 16;
break;
case 33:
result += 4;
break;
case 34:
result -= 33;
break;
case 35:
result = 19;
break;
case 36:
result += 16;
break;
case 37:
result += 4;
break;
case 38:
result -= 33;
break;
case 39:
result = 19;
break;
case 40:
result += 5;
break;
case 41:
result += 2;
break;
case 42:
result += 7;
break;
case 43:
result -= 5;
break;
case 44:
result += 20;
break;
case 45:
result -= 35;
break;
case 46:
result += 1;
break;
case 47:
result = 555;
break;
case 48:
result -= 7;
break;
case 49:
result -= 33;
break;
case 50:
result = 28;
break;
case 51:
result = 59;
break;
case 52:
result += 16;
break;
case 53:
result += 4;
break;
case 54:
result -= 33;
break;
case 55:
result = 19;
break;
case 56:
result += 16;
break;
case 57:
result += 4;
break;
case 58:
result -= 33;
break;
case 59:
result = 19;
break;
case 60:
result += 5;
break;
case 61:
result += 2;
break;
case 62:
result += 7;
break;
case 63:
result -= 5;
break;
case 64:
result += 20;
break;
case 65:
result -= 35;
break;
case 66:
result += 1;
break;
case 67:
result = 555;
break;
case 68:
result -= 7;
break;
case 69:
result -= 33;
break;
case 70:
result = 28;
break;
case 71:
result = 59;
break;
case 72:
result += 16;
break;
case 73:
result += 4;
break;
case 74:
result -= 33;
break;
case 75:
result = 19;
break;
case 76:
result += 16;
break;
case 77:
result += 4;
break;
case 78:
result -= 33;
break;
case 79:
result = 19;
break;
}
}
}
gettimeofday(&tv2, NULL);
if (tv1.tv_usec > tv2.tv_usec)
{
tv2.tv_sec--;
tv2.tv_usec += 1000000;
}
cout << "Time packed " << tv2.tv_sec - tv1.tv_sec << "." << tv2.tv_usec -
tv1.tv_usec << endl;
return result;
}
int sparse(int test)
{
struct timeval tv1, tv2;
int result = 90;
gettimeofday(&tv1, NULL);
for (int i = 0; i < 2000; ++i) // takes about 4 seconds
{
for (int j = 0; j < 1000000; ++j)
{
switch (test)
{
case 0:
result += 5;
break;
case 10:
result += 2;
break;
case 11:
result += 7;
break;
case 12:
result -= 5;
break;
case 40:
result += 20;
break;
case 47:
result -= 35;
break;
case 60:
result += 1;
break;
case 61:
result = 555;
break;
case 93:
result -= 7;
break;
case 100:
result -= 33;
break;
case 132:
result = 28;
break;
case 137:
result = 59;
break;
case 143:
result += 16;
break;
case 147:
result += 4;
break;
case 162:
result -= 33;
break;
case 181:
result = 19;
break;
case 216:
result += 16;
break;
case 417:
result += 4;
break;
case 458:
result -= 33;
break;
case 509:
result = 19;
break;
case 600:
result += 5;
break;
case 610:
result += 2;
break;
case 711:
result += 7;
break;
case 712:
result -= 5;
break;
case 740:
result += 20;
break;
case 847:
result -= 35;
break;
case 860:
result += 1;
break;
case 961:
result = 555;
break;
case 993:
result -= 7;
break;
case 1010:
result -= 33;
break;
case 1132:
result = 28;
break;
case 1237:
result = 59;
break;
case 1243:
result += 16;
break;
case 1647:
result += 4;
break;
case 1962:
result -= 33;
break;
case 2101:
result = 19;
break;
case 2116:
result += 16;
break;
case 2417:
result += 4;
break;
case 2458:
result -= 33;
break;
case 2509:
result = 19;
break;
case 5000:
result += 5;
break;
case 5010:
result += 2;
break;
case 5011:
result += 7;
break;
case 5012:
result -= 5;
break;
case 5040:
result += 20;
break;
case 5047:
result -= 35;
break;
case 5060:
result += 1;
break;
case 5061:
result = 555;
break;
case 5093:
result -= 7;
break;
case 5100:
result -= 33;
break;
case 5132:
result = 28;
break;
case 5137:
result = 59;
break;
case 5143:
result += 16;
break;
case 5147:
result += 4;
break;
case 5162:
result -= 33;
break;
case 5181:
result = 19;
break;
case 5216:
result += 16;
break;
case 5417:
result += 4;
break;
case 5458:
result -= 33;
break;
case 5509:
result = 19;
break;
case 5600:
result += 5;
break;
case 5610:
result += 2;
break;
case 5711:
result += 7;
break;
case 6712:
result -= 5;
break;
case 6740:
result += 20;
break;
case 6847:
result -= 35;
break;
case 6860:
result += 1;
break;
case 6961:
result = 555;
break;
case 6993:
result -= 7;
break;
case 7010:
result -= 33;
break;
case 7132:
result = 28;
break;
case 7237:
result = 59;
break;
case 7243:
result += 16;
break;
case 7647:
result += 4;
break;
case 7962:
result -= 33;
break;
case 8101:
result = 19;
break;
case 8116:
result += 16;
break;
case 8417:
result += 4;
break;
case 8458:
result -= 33;
break;
case 8509:
result = 19;
break;
}
}
}
gettimeofday(&tv2, NULL);
if (tv1.tv_usec > tv2.tv_usec)
{
tv2.tv_sec--;
tv2.tv_usec += 1000000;
}
cout << "Time sparse " << tv2.tv_sec - tv1.tv_sec << "." << tv2.tv_usec -
tv1.tv_usec << endl;
return result;
}
int main()
{
int a, b, c, d, e, f;
cout << "\n first" << endl;
a = packed(0);
b = sparse(0);
cout << "\n middle" << endl;
c = packed(40);
d = sparse(5000);
cout << "\n last" << endl;
e = packed(78);
f = sparse(8509);
return 0;
// results are not used
// just there to fool compiler
}
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