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Re: math-68881.h vs -ffast-math


On 02/09/2011 03:39 PM, Vincent Rivière wrote:
> The file gcc/config/m68k/math-68881.h is distributed with GCC. It is
> about inlining the libm functions using FPU instructions on m68k
> targets.
> 
> But -ffast-math seems to serve the same purpose, even better.
> 
> My question: Is math-68881.h still useful for some purpose ?

You're certainly correct that incorporating the functions into the compiler
directly is better than an external header file.  Not for the least of reasons
that e.g. the Fortran compiler can use the builtins, but not the header file.

It looks like not all of the functions in math-68881.h have been transfered
into the m68k.md file.  Almost all of the functions have a builtin equivalent
though -- look at the i386.md file for pointers.

Patches to add the patterns to support the missing builtins one at a time
would be welcome.


r~


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