[PATCH v2] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions

On Tue, 12 Nov 2013, M?ns Rullg?rd wrote:

Nicolas Pitre [off-list ref] writes:

quoted

On Tue, 12 Nov 2013, Ben Dooks wrote:

quoted

Given these are single instructoins for ARM, is it possible we could
make a table of all the callers and fix them up when we initialise
as we do for the SMP/UP case and for page-offset?

Not really.  Calls to those functions are generated by the compiler 
implicitly when a divisor operand is used and therefore we cannot 
annotate those calls.  We'd have to use special accessors everywhere to 
replace the standard division operand (like we do for 64 by 32 bit 
divisions) but I doubt that people would accept that.

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.

Is it worth it?  I'm not sure.


Nicolas