[llvm-commits] Fix Bug 13574: Add more double float shrinking optimizations

[Stephen Canon]

Do I understand correctly that this optimization would transform cos((double)floatval) --> (double)cosf(floatval)?  That's not a acceptable transformation, numerically.

One should also consider that there are a number of platforms supported by LLVM (not naming names) on which the float variants of libm functions are significantly *slower* than the double-precision variants.

- Steve

On Aug 15, 2012, at 2:33 PM, Weiming Zhao <weimingz at codeaurora.org> wrote:

> Hi,
>  
> This patch fixes http://llvm.org/bugs/show_bug.cgi?id=13574
>  
> Current LLVM only supports 5 double->float shrinking optimizations (floor->floorf, ceil->ceilf,round->roundf, rint->rintf() and nearbyint->nearbyintf).
>  
> This patch adds more math functions, for example, pow->powf, sin->sinf, cos->cosf, etc.
>  
> In this patch:
> 1.     Since cos(), pow() and exp2() already have their own optimizers: CosPot, PowOpt and Exp2Opt, respectively, I let them inherit from UnaryDoubleFPOpt and in their CallOptimizer(), I let them to call the base class’s CallOptimizer() first.
> For this change, I have to hoist the definition of UnaryDoubleFPOpt ahead of CosOpt.
>  
> 2.       Since some functions are not available on Windows, I updated TargetLibraryInfo to mark them as unavailable.
>  
> 3.       A unit test case is updated to test this patch.
>  
> Please help to review them.
>  
> Thanks,
> Weiming
> <0001-Bug-13574-More-double-float-shrinking-optimizations-f.patch>_______________________________________________
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