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This is the mail archive of thelibc-alpha@sourceware.orgmailing list for theglibc project.
Re: Remove powerpc32 sqrt wrappers
On Thu, 24 Aug 2017, Gabriel F. T. Gomes wrote:> On Thu, 24 Aug 2017 14:23:36 +0000> Joseph Myers <joseph@codesourcery.com> wrote:> > >Would any powerpc people like to comment on this patch > ><https://sourceware.org/ml/libc-alpha/2017-08/msg01028.html>?> > I had never ran benchtests of functions from math (only from string)> before you sent this patch (so I'm spending some time learning about its> outputs). I would like to comment on it in the following days.Note that benchtests of sqrt deliberately use -fno-builtin, specifically because the point is to benchmark glibc's implementations rather than the compiler's inline code.Thus those benchtests may indicate how much performance (if any) is gained (given -fno-builtin) from the custom sqrt wrappers, compared with code generated by a modern GCC version that can do shrink wrapping (the comments in the powerpc32 wrappers say "Until gcc supports prologue shrink-wrapping this is the best we can do.", i.e. they were intended to improve on the performance of code built with old GCC). But they are also fairly peripheral to my main point (that in the normal case, without -fno-builtin, these wrappers will only ever be called for non-performance-relevant error cases, and not even those with -fno-math-errno).-- Joseph S. Myersjoseph@codesourcery.com
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