Tcl Source Code

Tcl_ListObjReplace() should use memmove() instead
of a manual copy loop to shift list elements in memory.
The attached patch decreases time spent inTcl_ListObjReplace() 
from 5.2% to 1.7% of overall runtime of
tclbench on a ppc 7455 (i.e. 200% speed increase).

also contained in the patch a small performance tweak to tclHash.c: 
this hoists a few constant pointer dereferences out
of loops to eliminate redundant loads that the gcc optimizer didn't
deal with. Decreases time spend in Tcl_FindHashEntry() by 10% 
over a full run of the tcl testuite on a ppc 7455.

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but memmove() is already used in a number of places in the core (in 
tclParseExpr.c, tclIOGT.c, tclIO.c) so this does not create a new 
dependency, configure and compat/string.h already deal with it...

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The only thing to watch out for is whether memmove() is
going to have any additional requirements on the configure
script and portability. Apart from that, no objection
whatsoever. :^)

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Sounds good to me.

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Jeff,
went ahead and committed this to HEAD and core-8-4-branch, hope that's 
ok, the changes are minor and should not be controversial.

File Added - 108375: perf-tweak-core-8-4-branch.diff

File Added - 108374: perf-tweak-HEAD.diff