You may think that this is a silly patch, but it's real.
mops.pasm uses a very simple loop to figure out how many operations a
second parrot can go. However, the loop it uses is inefficient: it
does a "branch" *and* an "eq" every time around. Real code shouldn't
do this: I try and explain this at http://www.parrotcode.org/examples/
and it also features at
http://java.sun.com/docs/books/vmspec/2nd-edition/html/Compiling.doc.html#4182
The attached patch optimises the loop. Note that MOPS numbers now look
slightly different. For example, on my laptop:
OLD LOOP
mops.pasm: 11.713909
./mops: 108.442655
with -O3:
mops.pasm: 17.030964
./mops: 240.719673
NEW LOOP
mops.pasm: 10.647256
./mops: 73.574232
with -O3:
mops.pasm: 15.141514
./mops: 150.416772
Of course, the benchmark could be improved, but I suggest we should at
least change it to be good, tight code ;-)
Leon
--
Leon Brocard.............................http://www.astray.com/
Nanoware...............................http://www.nanoware.org/
.... Clones are people two
Index: examples/assembly/mops.pasm
===================================================================
RCS file: /home/perlcvs/parrot/examples/assembly/mops.pasm,v
retrieving revision 1.1
diff -u -r1.1 mops.pasm
--- examples/assembly/mops.pasm 2001/10/15 21:37:07 1.1
+++ examples/assembly/mops.pasm 2001/11/10 19:22:02
@@ -16,7 +16,7 @@
print I4
print "\n"
- set I1, 3
+ set I1, 2
mul I5, I4, I1
print "Estimated ops: "
@@ -25,9 +25,8 @@
time N1
-REDO: eq I2, I4, DONE
- add I2, I2, I3
- branch REDO
+REDO: add I2, I2, I3
+ lt I2, I4, REDO
DONE: time N5
