[Patch, fortran] PR77325 - ICE in gimplify_var_or_parm_decl, at gimplify.c:1933

[Paul Richard Thomas <paul dot richard dot thomas at gmail dot com>]

This is yet another deferred character problem occurring at exactly
the same place as 87239 and 84109. I found another bug while going
along and so have fixed that too.

Bootstrapped and regtested on FC28/x86_64.

I will apply all three to 8-branch in slightly more than one week's time.

Paul

2018-09-21  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/77325
    * trans-array.c (gfc_alloc_allocatable_for_assignment): If the
    rhs has a charlen expression, convert that and use it.
    * trans-expr.c (gfc_trans_assignment_1): The rse.pre for the
    assignment of deferred character array vars to a realocatable
    lhs should not be added to the exterior block since vector
    indices, for example, generate temporaries indexed within the
    loop.

2018-09-21  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/77325
    * gfortran.dg/deferred_character_22.f90 : New test.

Index: gcc/fortran/trans-array.c
===================================================================
*** gcc/fortran/trans-array.c	(revision 264426)
--- gcc/fortran/trans-array.c	(working copy)
*************** gfc_alloc_allocatable_for_assignment (gf
*** 9964,9969 ****
--- 9964,9978 ----
  	      tmp = concat_str_length (expr2);
  	      expr2->ts.u.cl->backend_decl = gfc_evaluate_now (tmp, &fblock);
  	    }
+ 	  else if (!tmp && expr2->ts.u.cl->length)
+ 	    {
+ 	      gfc_se tmpse;
+ 	      gfc_init_se (&tmpse, NULL);
+ 	      gfc_conv_expr_type (&tmpse, expr2->ts.u.cl->length,
+ 				  gfc_charlen_type_node);
+ 	      tmp = tmpse.expr;
+ 	      expr2->ts.u.cl->backend_decl = gfc_evaluate_now (tmp, &fblock);
+ 	    }
  	  tmp = fold_convert (TREE_TYPE (expr1->ts.u.cl->backend_decl), tmp);
  	}
  
Index: gcc/fortran/trans-expr.c
===================================================================
*** gcc/fortran/trans-expr.c	(revision 264427)
--- gcc/fortran/trans-expr.c	(working copy)
*************** gfc_trans_assignment_1 (gfc_expr * expr1
*** 10275,10291 ****
    /* When assigning a character function result to a deferred-length variable,
       the function call must happen before the (re)allocation of the lhs -
       otherwise the character length of the result is not known.
!      NOTE: This relies on having the exact dependence of the length type
       parameter available to the caller; gfortran saves it in the .mod files.
!      NOTE ALSO: The concatenation operation generates a temporary pointer,
       whose allocation must go to the innermost loop.
!      NOTE ALSO (2): Elemental functions may generate a temporary, too.  */
    if (flag_realloc_lhs
        && expr2->ts.type == BT_CHARACTER && expr1->ts.deferred
        && !(lss != gfc_ss_terminator
  	   && rss != gfc_ss_terminator
! 	   && ((expr2->expr_type == EXPR_FUNCTION
! 		&& expr2->value.function.esym != NULL
  		   && expr2->value.function.esym->attr.elemental)
  	       || (expr2->expr_type == EXPR_FUNCTION
  		   && expr2->value.function.isym != NULL
--- 10275,10295 ----
    /* When assigning a character function result to a deferred-length variable,
       the function call must happen before the (re)allocation of the lhs -
       otherwise the character length of the result is not known.
!      NOTE 1: This relies on having the exact dependence of the length type
       parameter available to the caller; gfortran saves it in the .mod files.
!      NOTE 2: Vector array references generate an index temporary that must
!      not go outside the loop. Otherwise, variables should not generate
!      a pre block.
!      NOTE 3: The concatenation operation generates a temporary pointer,
       whose allocation must go to the innermost loop.
!      NOTE 4: Elemental functions may generate a temporary, too.  */
    if (flag_realloc_lhs
        && expr2->ts.type == BT_CHARACTER && expr1->ts.deferred
        && !(lss != gfc_ss_terminator
  	   && rss != gfc_ss_terminator
! 	   && ((expr2->expr_type == EXPR_VARIABLE && expr2->rank)
! 	       || (expr2->expr_type == EXPR_FUNCTION
! 		   && expr2->value.function.esym != NULL
  		   && expr2->value.function.esym->attr.elemental)
  	       || (expr2->expr_type == EXPR_FUNCTION
  		   && expr2->value.function.isym != NULL
Index: gcc/testsuite/gfortran.dg/deferred_character_22.f90
===================================================================
*** gcc/testsuite/gfortran.dg/deferred_character_22.f90	(nonexistent)
--- gcc/testsuite/gfortran.dg/deferred_character_22.f90	(working copy)
***************
*** 0 ****
--- 1,27 ----
+ ! { dg-do run }
+ !
+ ! Test the fix for PR77325, which casued an ICE in the gimplifier. The
+ ! segafults in 'contains_struct_check' were found while diagnosing the PR.
+ !
+ ! Contributed by Gerhard Steinmetz  <gerhard.steinmetz.fortran@t-online.de>
+ !
+ program p
+    character(3), parameter :: a(3) = ['abc', 'def', 'ghi']
+    character(1), parameter :: c(3) = ['a', 'b', 'c']
+    character(:), allocatable :: z(:)
+    z = c([3,2])          ! Vector subscripts caused an iCE in the gimplifier.
+    if (any (z .ne. ['c', 'b'])) stop 1
+    z = c
+    if (any (z .ne. ['a', 'b', 'c'])) stop 2
+    z = c(2:1:-1)
+    if (any (z .ne. ['b', 'a'])) stop 3
+    z = c(3)
+    if (any (z .ne. ['c', 'c'])) stop 4
+    z = a([3,1,2])
+    if (any (z .ne. ['ghi', 'abc', 'def'])) stop 5
+    z = a(1:2)(2:3)       ! Substrings caused a segfault in 'contains_struct_check'.
+    if (any (z .ne. ['bc', 'ef'])) stop 6
+    z = a([2,3,1])(2:3)   ! ditto
+    if (any (z .ne. ['ef', 'hi', 'bc'])) stop 7
+    deallocate (z)
+ end