[Bug fortran/90578] Wrong code with LSHIFT and optimization

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90578

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |NEW
         Resolution|INVALID                     |---

--- Comment #2 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
LSHIFT is a GNU extension defined as

LSHIFT returns a value corresponding to I with all of the bits shifted left by
SHIFT places. If the absolute value of SHIFT is greater than BIT_SIZE(I), the
value is undefined. Bits shifted out from the left end are lost; zeros are
shifted in from the opposite end.

I don't see any mention of "left-shift by negative value is undefined".

If it is the case for the gfortran implementation, this should be documented.