[Bug fortran/51904] New: Internal Compiler Error on size function evaluation

[Bug fortran/51904] New: Internal Compiler Error on size function evaluation

[david.sagan at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51904

             Bug #: 51904
           Summary: Internal Compiler Error on size function evaluation
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: david.sagan@gmail.com


The following program produces an "internal compiler error" in 4.6.3. gcc 4.5
does not show the bug:

subroutine qp_draw_polyline_basic (x)
  implicit none
  real :: x(:), f
  f = 0
  print *, size(f*x)
end subroutine

Result:

mc66:~/Bmad/bmad_dist/bug> uname -a
Darwin mc66.lns.cornell.edu 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun  7
16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386

mc66:~/Bmad/bmad_dist/bug> gfortran --version
GNU Fortran (GCC) 4.6.2

mc66:~/Bmad/bmad_dist/bug> gfortran -c bug.f90
f951: internal compiler error: Segmentation fault

Of course the workaround is easy: Just replace "size(f*x)" with "size(x)".

[Bug fortran/51904] [4.6/4.7 Regression] ICE on SIZE function evaluation

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51904

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code
                 CC|                            |burnus at gcc dot gnu.org
      Known to work|                            |4.1.2, 4.3.4, 4.4.0, 4.5.3
   Target Milestone|---                         |4.6.3
            Summary|Internal Compiler Error on  |[4.6/4.7 Regression] ICE on
                   |size function evaluation    |SIZE function evaluation
      Known to fail|                            |4.6.3, 4.7.0

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-01-19 16:25:54 UTC ---
 Invalid read of size 8
    at 0x57C267: resolve_code(gfc_code*, gfc_namespace*) (resolve.c:8316)
    by 0x57DE2B: gfc_resolve_blocks(gfc_code*, gfc_namespace*) (resolve.c:9038)
    by 0x5819B5: resolve_code(gfc_code*, gfc_namespace*) (resolve.c:9307)
    by 0x58412E: resolve_codes(gfc_namespace*) (resolve.c:13931)

That's:
resolve_transfer (gfc_code *code)
{
...
  if (exp == NULL || (exp->expr_type != EXPR_VARIABLE
                      && exp->expr_type != EXPR_FUNCTION))
    return;
...
  sym = exp->symtree->n.sym; /* <<< segfault */

The problem is that:
(gdb) p exp->symtree
$5 = (gfc_symtree *) 0x0
(gdb) p exp->value.function
$6 = {actual = 0x15fc710, name = 0xf5939f "size", isym = 0x162c0e8, esym = 0x0}


The program works with pathf95, g95, NAG f95 and gfortran 4.1 to 4.5, but
segfaults with 4.6 and 4.7

 * * *

I tried the following patch [only the first part is needed] - but it fails then
later at

  Invalid read of size 8
    at 0x5D3E91: gfc_conv_expr_reference(gfc_se*, gfc_expr*)
(trans-expr.c:5510)
    by 0x5F2686: gfc_trans_transfer(gfc_code*) (trans-io.c:2306)
    by 0x5A4987: trans_code(gfc_code*, tree_node*) (trans.c:1522)
    by 0x5F01E9: build_dt(tree_node*, gfc_code*) (trans-io.c:1832)
    by 0x5A49A7: trans_code(gfc_code*, tree_node*) (trans.c:1494)
    by 0x5CAA8A: gfc_generate_function_code(gfc_namespace*) (trans-decl.c:5329)

There, the issue is:

  if (expr->expr_type == EXPR_FUNCTION
      && ((expr->value.function.esym ....
          || (!expr->value.function.esym
              && expr->symtree->n.sym->attr.pointer

Namely: If "esym" does not exist, the code assumes that the symtree is
available - but in this case one has only an "isym".

I have somehow the feeling that the error must be up-chain.

--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -8303,4 +8303,5 @@ resolve_transfer (gfc_code *code)

-  if (exp == NULL || (exp->expr_type != EXPR_VARIABLE
-                     && exp->expr_type != EXPR_FUNCTION))
+  if (exp == NULL
+      || (exp->expr_type != EXPR_VARIABLE && exp->expr_type != EXPR_FUNCTION)
+      || (exp->expr_type == EXPR_FUNCTION && exp->value.function.isym))
     return;
@@ -8315,3 +8316,4 @@ resolve_transfer (gfc_code *code)

-  sym = exp->symtree->n.sym;
+  sym = exp->expr_type == EXPR_FUNCTION && exp->value.function.esym
+       ? exp->value.function.esym : exp->symtree->n.sym;
   ts = &sym->ts;

[Bug fortran/51904] [4.6/4.7 Regression] ICE on SIZE function evaluation

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51904

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-01-19 16:50:33 UTC ---
Fails:
  gcc version 4.6.0 20100828 (experimental) [trunk revision 163612] (GCC)
Works:
  gcc version 4.6.0 20100716 (experimental) [trunk revision 162255] (GCC)
(Note: The builds might have local patches.)


I think it's due to the patch Rev. 162648 of 2010-07-28
  http://gcc.gnu.org/viewcvs?view=revision&revision=162648

That patch tries to compile-time simplify SIZE but also changes for
nonconstant-bound arrays, e.g., SIZE(X ** 2) to  SIZE(X).

Possibly the additional resolution only happens if also a symtree is available?
That would be a change to gfc_build_intrinsic_call.

If one replaces
  print *, size(f*x)
by
  i = size(f*x)
  print *, i
the program works and one finds in the dump:
  i = (integer(kind=4))
        MAX_EXPR <(D.1879->dim[0].ubound - D.1879->dim[0].lbound) + 1, 0>;

[Bug fortran/51904] [4.6/4.7 Regression] ICE on SIZE function evaluation

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51904

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4
                 CC|                            |jakub at gcc dot gnu.org

[Bug fortran/51904] [4.6/4.7 Regression] ICE on SIZE function evaluation

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51904

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-01-19 20:22:43 UTC ---
Author: burnus
Date: Thu Jan 19 20:22:33 2012
New Revision: 183310

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183310
Log:
2012-01-19  Tobias Burnus  <burnus@net-b.de>

        PR fortran/51904
        * expr.c (gfc_build_intrinsic_call): Also set the symtree.

2012-01-19  Tobias Burnus  <burnus@net-b.de>

        PR fortran/51904
        * gfortran.dg/intrinsic_size_2.f90: New.


Added:
    trunk/gcc/testsuite/gfortran.dg/intrinsic_size_2.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/expr.c
    trunk/gcc/testsuite/ChangeLog

[Bug fortran/51904] [4.6/4.7 Regression] ICE on SIZE function evaluation

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51904

--- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-01-19 22:21:47 UTC ---
Author: burnus
Date: Thu Jan 19 22:21:43 2012
New Revision: 183314

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183314
Log:
2012-01-19  Tobias Burnus  <burnus@net-b.de>

        PR fortran/51904
        *expr.c (gfc_build_intrinsic_call): Also set the symtree.

2012-01-19  Tobias Burnus  <burnus@net-b.de>

        PR fortran/51904
        * gfortran.dg/intrinsic_size_2.f90: New.


Added:
    branches/gcc-4_6-branch/gcc/testsuite/gfortran.dg/intrinsic_size_2.f90
Modified:
    branches/gcc-4_6-branch/gcc/fortran/ChangeLog
    branches/gcc-4_6-branch/gcc/fortran/expr.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug fortran/51904] [4.6/4.7 Regression] ICE on SIZE function evaluation

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51904

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED

--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-01-19 22:26:26 UTC ---
FIXED on the trunk (4.7) and on the 4.6 branch.

David, thanks for the bug report!