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Date: Thu, 19 Nov 2009 21:07:00 -0000
From: Jeff Law <law@redhat.com>
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: rostedt@goodmis.org, David Daney <ddaney@caviumnetworks.com>,         Linus Torvalds <torvalds@linux-foundation.org>,         Andrew Haley <aph@redhat.com>,         Richard Guenther <richard.guenther@gmail.com>,         Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,         LKML <linux-kernel@vger.kernel.org>,         Andrew Morton <akpm@linux-foundation.org>,         Heiko Carstens <heiko.carstens@de.ibm.com>, feng.tang@intel.com,         Fr??d??ric Weisbecker <fweisbec@gmail.com>,         Peter Zijlstra <peterz@infradead.org>, jakub@redhat.com,         gcc@gcc.gnu.org
Subject: Re: BUG: GCC-4.4.x changes the function frame on some functions
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On 11/19/09 12:50, H. Peter Anvin wrote:
>
> Calling the profiler immediately at the entry point is clearly the more
> sane option.  It means the ABI is well-defined, stable, and independent
> of what the actual function contents are.  It means that ABI isn't the
> normal C ABI (the __fentry__ function would have to preserve all
> registers), but that's fine...
>    
Note there are targets (even some old x86 variants) that required the 
profiling calls to occur after the prologue.  Unfortunately, nobody 
documented *why* that  was the case.   Sigh.

Jeff