[Bug fortran/83900] [8 Regression] ICE in gfc_simplify_matmul, at fortran/simplify.c:4593

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83900

--- Comment #10 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Sat, Jan 20, 2018 at 03:22:50PM +0000, dominiq at lps dot ens.fr wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83900
> 
> --- Comment #9 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> The original test in comment 0 still fails at r256917 on darwin with
> 
> pr83900.f90:4:0:
> 
>     print *, matmul(a, b)
> 
> internal compiler error: in fold_convert_loc, at fold-const.c:2402
> 
> Should I reopen this PR or open a new one?
> 

Interesting.  gfortran.dg/matmul_17.f90 is essentially the 
code in comment #0 without the IO statement.  The backtrace
in comment #0 is caused by the assert() I removed, which is
bogus.  I think a new PR is needed.  It seems matmul is 
hosed

   integer, parameter :: a(3,2) = 1
   real, parameter :: b(2,3) = 2
   real, parameter :: c(3,3) = matmul(a,b)
   real d(3,3)
   d = matmul(a,b)
   print '(9F5.1)', c
   print '(9F5.1)', d
% gfcx -o z -fno-frontend-optimize a.f90
% ./z
  4.0  4.0  4.0  4.0  4.0  4.0  4.0  4.0  4.0
  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0

-fno-frontend-optimize is  not needed to get the above.