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Re: [PATCH-v4] [SPARC] Add a workaround for the LEON3FT store-store errata


On 2017-07-11 09:21, Eric Botcazou wrote:

Applied without the undocumented tweaks to the divdf3_fix and sqrtdf2_fix
patterns.  Why are 2 nops necessary here?  The stored value doesn't matter.
And the length attribute should be adjusted if nops are added to the pattern.


The first nop was added to prevent sequence A from appearing (store -> fdivd -> std). But as you say, it is not needed as we do not read the value written by the std. The second nop was added to prevent sequence B (std -> store) and this one seems necessary as the value written by the store might be used later. OK to submit a new patch with only the second nop and a correct length attribute?

--
Daniel Cederman
Cobham Gaisler


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