Messages in this thread | | | Date | Mon, 2 Jan 2006 22:23:35 +0000 | From | Russell King <> | Subject | Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers |
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On Mon, Jan 02, 2006 at 07:51:32PM +0100, Arjan van de Ven wrote: > On Mon, 2006-01-02 at 19:44 +0100, Krzysztof Halasa wrote: > > Ingo Molnar <mingo@elte.hu> writes: > > > > > what is the 'deeper problem'? I believe it is a combination of two > > > (well-known) things: > > > > > > 1) people add 'inline' too easily > > > 2) we default to 'always inline' > > > > For example, I add "inline" for static functions which are only called > > from one place. > > you know what? gcc inlines those automatic even without you typing > "inline". (esp if you have unit-at-a-time enabled)
Rubbish it will.
static void fn1(void *f) { }
void fn2(void *f) { fn1(f); }
on ARM produces:
.text .align 2 .type fn1, %function fn1: @ args = 0, pretend = 0, frame = 0 @ frame_needed = 0, uses_anonymous_args = 0 @ link register save eliminated. @ lr needed for prologue mov pc, lr .size fn1, .-fn1 .align 2 .global fn2 .type fn2, %function fn2: @ args = 0, pretend = 0, frame = 0 @ frame_needed = 0, uses_anonymous_args = 0 @ link register save eliminated. @ lr needed for prologue b fn1 .size fn2, .-fn2 .ident "GCC: (GNU) 3.3 20030728 (Red Hat Linux 3.3-16)"
You can't get a simpler function than fn1 to automatically inline.
GCC will only automatically inline using -O3. We don't use -O3 with the kernel - only -O2 and -Os.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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