Messages in this thread |  | | | Date | Sat, 26 Apr 2008 22:07:26 -0700 (PDT) | | Subject | find_new_bit bloat from x86 tree... | | From | David Miller <> | |
Ingo, what the heck is this?
commit 64970b68d2b3ed32b964b0b30b1b98518fde388e
Author: Alexander van Heukelum <heukelum@mailshack.com>
Date: Tue Mar 11 16:17:19 2008 +0100
x86, generic: optimize find_next_(zero_)bit for small constant-size bitmaps
Thanks for bloating up the inline expansion of this thing on every
architecture that doesn't do __ffs() in a simple sequence of a few
instructions like x86 does.
Now every call that matches your tests gets this turd inline:
static inline unsigned long __ffs(unsigned long word)
{
int num = 0;
#if BITS_PER_LONG == 64
if ((word & 0xffffffff) == 0) {
num += 32;
word >>= 32;
}
#endif
if ((word & 0xffff) == 0) {
num += 16;
word >>= 16;
}
if ((word & 0xff) == 0) {
num += 8;
word >>= 8;
}
if ((word & 0xf) == 0) {
num += 4;
word >>= 4;
}
if ((word & 0x3) == 0) {
num += 2;
word >>= 2;
}
if ((word & 0x1) == 0)
num += 1;
return num;
}
as well as all of that address formation, bit shifting, and masking.
Please revert or make this conditional on something architectures can
opt-in for.
The version actually applied was posted only on linux-kernel, instead
of also CC:'ing linux-arch as previous versions had been. Nobody
commented on this version other than you Ingo.
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