Travis Vitek wrote:
Martin Sebor wrote:
[EMAIL PROTECTED] wrote:
Author: vitek
Date: Wed Jun 4 14:48:36 2008
New Revision: 663377
[...]
Modified: stdcxx/branches/4.2.x/src/valarray.cpp
URL:
http://svn.apache.org/viewvc/stdcxx/branches/4.2.x/src/valarray
.cpp?rev=663377&r1=663376&r2=663377&view=diff
===============================================================
===============
--- stdcxx/branches/4.2.x/src/valarray.cpp (original)
+++ stdcxx/branches/4.2.x/src/valarray.cpp Wed Jun 4 14:48:36 2008
@@ -41,8 +41,12 @@
{
_RWSTD_SIZE_T __n = _C_length.size ();
- while (__n && _C_r_length [__n - 1] == _C_length [__n - 1] - 1)
- --__n;
+ for (/**/; __n; --__n)
+ {
The brace should be on the line above :)
Blarg!
+ if ( _C_length [__n - 1]
+ && _C_r_length [__n - 1] != _C_length [__n - 1] - 1)
Also, I wonder if it might help generate more optimal code to write
the loop like so:
while (__n) {
--__n;
if (_C_length [n] && _C_r_length [n] != _C_length [n] - 1)
break;
}
It is possible it would help generate better code, but this code changes
the behavior of the loop. We now decrement __n before checking the
condition; when we break __n will be off-by-one. Obviously we can deal
with that by incrementing __n before the break.
I should have looked at the rest of the file and not just the diff
before saying anything.
I'll take a quick look at some disassembly and decide if it is worth
making the change or not.
It probably doesn't matter in the grand scheme of things. The new
gslice computes the indices just once and caches the result which
should be a much more significant optimization.
Martin
