[Bug tree-optimization/98176] Loop invariant memory could not be hoisted when nonpure_call in loop body

[wwwhhhyyy333 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98176

--- Comment #6 from Hongyu Wang <wwwhhhyyy333 at gmail dot com> ---
(In reply to Richard Biener from comment #5)
> (In reply to Hongyu Wang from comment #4)
> > (In reply to Richard Biener from comment #3)
> >  
> > > I see ret[0] has store-motion applied.  You don't see it vectorized
> > > because GCC doesn't know how to vectorize sincos (or cexpi which is
> > > what it lowers it to).
> > 
> > I doubt so, after manually store motion
> > 
> > #include <cmath>
> > 
> > float foo(                
> >                 int *x,                      
> >                 int n,                 
> >                 float tx
> >                 )   
> > {
> >         float ret[n];
> >         float tmp;
> > 
> >         #pragma omp simd
> >         for (int i = 0; i < n; i++)
> >         {
> >             float s, c;                    
> > 
> >             sincosf( tx * x[i] , &s, &c );  
> > 
> >             tmp += s*c; 
> >         }
> > 
> >         ret[0] += tmp; 
> > 
> >         return ret[0];
> > }
> > 
> > with -Ofast -fopenmp-simd -std=c++11 it could be vectorized to call   
> > _ZGVbN4vvv_sincosf
> > 
> > ret[0] is moved for sinf() case, but not sincosf() with above options.
> 
> What target are you targeting?  Can you provide the sincosf prototype
> from your math.h?  (please attach preprocessed source).
> 
> I cannot reproduce sincosf _not_ being lowered to cexpif and thus
> no longer having memory writes.
> 

I used g++ on godbolt:

https://gcc.godbolt.org/z/rv45MK

Below extern is sufficient for g++ to vectorize the code

__attribute__ ((__simd__ ("notinbranch"))) extern void sincosf (float __x,
float *__sinx, float *__cosx); 

compiled with -Ofast -fopenmp-simd -std=c++11 -march=x86-64