[compiler-rt] r213467 - ARM: fix division in some cases

Saleem Abdulrasool compnerd at compnerd.org
Sun Jul 20 11:31:36 PDT 2014

On Sun, Jul 20, 2014 at 10:06 AM, Joerg Sonnenberger <
joerg at britannica.bec.de> wrote:

> On Sun, Jul 20, 2014 at 04:44:21AM -0000, Saleem Abdulrasool wrote:
> > Rather than computing the target at runtime, use a jumptable instead.
>  This
> > trades a bit of storage for performance.  The overhead is 32-bytes for
> each of
> > the three routines, but avoid the calculation of the offset.
> Have you measured that it is actually faster? There is an outstanding
> patch for fixing the computation...

Using the jump table was a much easier thing for me to do when fixing the
computation for the Thumb mode compilation.  The real motivation here was
to use the Thumb mode instructions in the ARMv6T2-early ARMv7 chips which
lack the udiv/sdiv instructions but do support clz.  I should be able to
run benchmarks on the machine that I tested with (ARMv7).

> Joerg
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Saleem Abdulrasool
compnerd (at) compnerd (dot) org
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