digitalmars.D.bugs - [Issue 4244] New: AA insert from fixed-sized array much slower than from equivalent struct
- d-bugmail puremagic.com (51/51) May 27 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4244
http://d.puremagic.com/issues/show_bug.cgi?id=4244 Summary: AA insert from fixed-sized array much slower than from equivalent struct Product: D Version: future Platform: x86 OS/Version: Windows Status: NEW Keywords: performance Severity: normal Priority: P2 Component: DMD AssignedTo: nobody puremagic.com ReportedBy: bearophile_hugs eml.cc This D2 program gets much slower if foo1() is used inside the main() instead of foo2() that apparently does something very similar (compiled with dmd v2.046, __gshared not used, compilation arguments -O -release -inline): import std.c.stdio: printf; int foo1(int x, int y) { static int[int[2]] cache; int[2] args = [x, y]; cache[args] = x; return x; } int foo2(int x, int y) { static struct Pair { int x, y; } static int[Pair] cache; Pair args = Pair(x, y); cache[args] = x; return x; } void main() { enum int N = 600; int tot; foreach (x; 1 .. N) foreach (y; 1 .. N) tot += foo1(x, y); printf("%d\n", tot); } An experiment shows that foo1 gets quite faster if the [x,y] is written inside the cache AA itself: int foo1(int x, int y) { static int[int[2]] cache; int[2] args = [x, y]; cache[[x, y]] = x; return x; } -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 27 2010