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Slug #687

Builtin fn makes unnecessary copy of arg

Added by John Abbott about 9 years ago. Updated almost 3 years ago.

Status:
Closed
Priority:
Normal
Assignee:
John Abbott
Category:
enhancing/improving
Target version:
CoCoA-5.4.0
Start date:
19 Apr 2015
Due date:
% Done:

100%

Estimated time:
0.75 h
Spent time:
1.15 h

Description

While testing/profiling IndetsIn (defined in BuiltinOneLiners.C) I noticed that the arg was copied by the fn, making it needlessly slow.

Investigate!

Related issues

Related to CoCoALib - Feature #658: Indets actually in a poly (or vector or matrix)Closed2015-01-22

Related to CoCoA-5 - Slug #31: theValue makes copyIn Progress2011-11-15

History

#1 Updated by John Abbott about 9 years ago

I ran the following test:

f := x+y+z+1;
f99 := f^99; // this is slow (~10s on my machine)
t0 := CpuTime();
for i := 1 to 100 do
  NoPrint := IndetsIn(f99);
endfor;
println "Loop time: ", TimeFrom(t0);

This reports a loop time of almost 10s.

An essentially identical test in CoCoALib is too fast to measure (less than 0.001s).

So the "overhead" is more than 99% -- wholly unacceptable!

#2 Updated by John Abbott almost 3 years ago

  • Status changed from New to Closed
  • Assignee set to John Abbott
  • Target version changed from CoCoA-5.?.? to CoCoA-5.4.0
  • % Done changed from 0 to 100
  • Estimated time set to 0.75 h

Now it takes 0.001s. No idea why it is fast now and not before.

Closing.

#3 Updated by Anna Maria Bigatti almost 3 years ago

John Abbott wrote:

Now it takes 0.001s. No idea why it is fast now and not before.

I guess is was for the move constructor

    RingElem(RingElem&& copy); // move ctor

defined in ring.H
// Revision 1.63  2020/10/05 19:30:31  abbott
// Summary: Added move ctor

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