Michael Van Canneyt wrote:

On Fri, 24 Dec 2004, Michalis Kamburelis wrote:


I tested your code and found that indeed version in ucopylist is
slightly faster (by about 9.5 / 7 =~ 1.357). Two things:

1. Speedup is only 1.357x, not 3x, like you said. Are you sure that
you're getting 3x speedup ? On what OS and with what FPC version are you
testing this ? I was doing tests with Linux/i386 with FPC 1.9.4 and
1.9.5 (from CVS 2004-12-20).

2. Still, speedup 1.357x may be significant in some cases so I
investigated what's the cause:

After many tests I found that this slight speedup is caused by the fact
that in ucopylist you declared string constants SListIndexError,
SListCapacityError and SListCountError as normal constants while with
original Classes unit these constants are taken from RTLConst unit that
defines them as resourcestrings.

Using resourcestrings in RTL is a must, since this allows to translate
error messages without modifying unit Classes sources.

However in this case exceptions are not raised, so resourcestrings are
not actually used. But it looks that any procedure that uses some
resourcestring in implementation is doomed to be slower than the similar
procedure that instead uses normal string consts, *even if this
procedure doesn't actually access the string at runtime*. It seems that
if some procedure uses resourcestring then upon entry it does some
lengthy initialization of this resourcestring, even if it will not
actually make use of that resourcestring.

This is because there is an extra (implicit) Try/Finally block.


Thank you and Peter for answers. This way I was able to see how try...finally section looks in assembler :) Anyway, I understand that the answer is "can't be speed up". OK, I can live with that.


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