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Date: Tue, 12 Nov 2013 10:20:10 -0500 (EST)
From: Nicolas Pitre <nicolas.pitre@linaro.org>
To: =?ISO-8859-15?Q?M=E5ns_Rullg=E5rd?= <mans@mansr.com>
cc: Ben Dooks <ben.dooks@codethink.co.uk>,
        Russell King - ARM Linux <linux@arm.linux.org.uk>,
        Stephen Boyd <sboyd@codeaurora.org>, linux-kernel@vger.kernel.org,
        Christopher Covington <cov@codeaurora.org>,
        Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] ARM: Use udiv/sdiv for __aeabi_{u}idiv library
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On Tue, 12 Nov 2013, Nicolas Pitre wrote:

> On Tue, 12 Nov 2013, Måns Rullgård wrote:
> 
> > It might be possible to extract this information from relocation tables.
> 
> True, but only for individual .o files.  Once the linker puts them 
> together the information is lost, and trying to infer what the linker 
> has done is insane.
> 
> Filtering the compiler output to annotate idiv calls before it is 
> assembled would probably be a better solution.

Another solution is to patch the call site from within __aeabi_idiv at 
run time using lr.  That wouldn't work in the presence of tail call 
optimization though.

Again this might not be worth it and patching __aeabi_idiv instead might 
be a good enough compromize.


Nicolas
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