Christian Franke wrote:
Pavel Roskin wrote:
On Tue, 2008-07-08 at 20:04 +0200, Christian Franke wrote:
With old gcc versions without the "rol" optimization, even the 16
bit swap should be a function:
Or better yet, an asm statement.
We should consider optimized assembly vs function call. Even the
32-bit swap could be shorter:
a: 86 c4 xchg %al,%ah
c: c1 c0 10 rol $0x10,%eax
f: 86 c4 xchg %al,%ah
11:
That's 7 bytes! ...
But the function call in the 32-bit case requires only 5 bytes :-)
Sorry, I was wrong here. The assumption about function call size was
only true for module-local calls. If a module calls a function in
kernel, each 5 byte call requires another 8 bytes for the ELF relocation
table entry.
Christian
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