Re: [patch, fortran] Handling of .and. and .or. expressions

[Steve Kargl <sgk at troutmask dot apl dot washington dot edu>]

On Thu, Jun 28, 2018 at 07:58:22AM +0200, Janus Weil wrote:
> 2018-06-27 23:47 GMT+02:00 Steve Kargl <sgk@troutmask.apl.washington.edu>:
> > On Wed, Jun 27, 2018 at 10:46:05PM +0200, Janus Weil wrote:
> >> 2018-06-27 21:34 GMT+02:00 Thomas Koenig <tkoenig@netcologne.de>:
> >> >
> >> > And we are not going to change Fortran semantics. And I also oppose
> >> > defining our own subset of Fortran in the hope that people will make
> >> > fewer mistakes.
> >> >
> >> > A function is something that produces a value.  If the value is not
> >> > needed to produce the correct result, the function need not be called.
> >>
> >> That's a bit oversimplified, isn't it?
> >
> > Technically, the standard says an operand need not be evaluate,
> > but you've asked people not to cite the Standard.  I've also
> > pointed you to F2018 Note 10.28 where it very clearly says that
> > a function need not be evaluated with example nearly identical
> > to the one in the PR.  PURE vs IMPURE (or unmarked) function
> > is a red herring.  The standard makes no distinction.
> 
> Look, Steve. This argument has been going in circles for weeks now. I
> think we can stop it here.
> 

I've already stated that I have no problem with the warning.  As
Thomas noted, gfortran should warn for both '.false. .and. check()'
and 'check() .and. .false.'

I am opposed to the change of TRUTH_AND_EXPR to TRUTH_ANDIF_EXPR,
where you are special casing logical expressions that involve
.and. and .or.  

In fact, I'll be submitting a bug report for a missed optimization.

subroutine foo(x,y)               subroutine foo(x,y)
   real x(10), y(10)                 real x(10), y(10)
   y = 0*sin(x)                      y = 0
end subroutine foo                end subroutine foo

.L2:                              pxor    %xmm0, %xmm0
   call    sinf                   movq    $0, 32(%rsi)
   pxor    %xmm1, %xmm1           movups  %xmm0, (%rsi)
   mulss   %xmm1, %xmm0           movups  %xmm0, 16(%rsi)
   movss   %xmm0, 0(%rbp,%rbx)
   addq    $4, %rbx
   cmpq    $40, %rbx
   jne     .L2

which I'm sure you'll just be thrilled with.

-- 
Steve