hfinkel added a comment.
In https://reviews.llvm.org/D47849#1124638, @Hahnfeld wrote:
> IMO this goes into the right direction, we should use the fast implementation
> in libdevice. If LLVM doesn't lower these calls in the NVPTX backend, I think
> it's ok to use header wrappers as CUDA already does.
>
> Two questions:
>
> 1. Can you explain where this is important for "correctness"? Yesterday I
> compiled a code using `sqrt` and it seems to spit out the correct results.
> Maybe that's relevant for other functions?
> 2. Incidentally I ran into a closely related problem: I can't `#include
> <math.h>` in translation units compiled for offloading, Clang complains about
> inline assembly for x86 (see below). Does that work for you?
>
> ``` In file included from /usr/include/math.h:413:
> /usr/include/bits/mathinline.h:131:43: error: invalid input constraint 'x' in
> asm __asm ("pmovmskb %1, %0" : "=r" (__m) : "x" (__x)); ^
> /usr/include/bits/mathinline.h:143:43: error: invalid input constraint 'x' in
> asm __asm ("pmovmskb %1, %0" : "=r" (__m) : "x" (__x)); ^ 2 errors generated.
> ```
Hrmm. I thought that we had fixed that already.
In case it's helpful, in an out-of-tree experimental target I have I ran into a
similar problem, and to fix that I wrote the following code in the target's
getTargetDefines function (in lib/Basic/Targets):
// If used as an OpenMP target on x86, x86 target feature macros are defined.
math.h
// and other system headers will include inline asm if these are defined.
Builder.undefineMacro("__SSE2_MATH__");
Builder.undefineMacro("__SSE_MATH__");
Repository:
rC Clang
https://reviews.llvm.org/D47849
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