On Thu, Jun 28, 2018 at 07:03:05PM +0200, Jakub Jelinek wrote: > > 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. > > For floating point, you generally need -ffast-math to be able to > optimize such computations away, sinf already has const attribute (at least > in C/C++), so with -ffast-math it is optimized.
Doesn't -ffast-math allow the violaton of the integrity of parentheses? That is, it allows more optimizations that violate the standard. -- Steve
