[Bug fortran/19925] Implied do-loop in an initialization expression is broken

[jvdelisle at gcc dot gnu dot org]

------- Comment #18 from jvdelisle at gcc dot gnu dot org  2008-02-01 04:43 
-------
With this patch:

@@ -1341,7 +1345,7 @@ find_array_section (gfc_expr *expr, gfc_
          cons = base;
        }

-      while (mpz_cmp (ptr, index) > 0)
+      while (mpz_cmp (ptr, index) > 0 && cons && cons->next)
        {
          mpz_add_ui (index, index, one);
          cons = cons->next;

The ICE for the second case on comment 10 goes away.  However, compile time is
very long as N increases:

  N = 1000,   .113 secs
      5000,   .702
     10000,  5.627
     12000, 11.091
     15000, 21.500
     20000, 42.228
     25000, 66.600

For N=100000 After several minutes we get the error message:

pr19925-10.f90:9.36:

INTEGER, PARAMETER :: M(N)=I(N:1:-1)
                                   1
Error: Initialization expression didn't reduce (1)

The ICE for this example is not related to the original problem in this PR.
Using the case of N = 5000, the printed results fo the array I, and m agree
with ifort and sun f95.  I am going to break this out as a separate PR and
submit this patch as a fix.  The failure to reduce, I am guessing is a
different problem.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19925