From patchwork Fri Jul 22 18:54:36 2011
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Subject: [Fotran] Fix PR 4755 - Do not free + reallocate a variable that is
 already allocated.
Date: Fri, 22 Jul 2011 08:54:36 -0000
From: Daniel Carrera <dcarrera@gmail.com>
X-Patchwork-Id: 106378
Message-Id: <4E29C76C.1070409@gmail.com>
To: gfortran <fortran@gcc.gnu.org>, gcc patches <gcc-patches@gcc.gnu.org>

Hello,

This is a simple patch that fixes PR 4755. Currently the ALLOCATE 
statement will free and re-allocate an already allocated scalar. The 
Fortran standard says that this is an error. The attached patch fixes 
the problem.

I am also attaching two tree dumps of the same program, compiled before 
and after the application of this patch. The test program is this:

program test
     integer, allocatable :: A(:), B[:]
     integer :: stat
     character(len=33) :: str
     allocate(A(1), B[*], stat=stat)
end program


If you compare the "before" and "after" files you'll see that with this 
patch GCC no longer tries to free and reallocate A(1). You will also 
notice that the block for B[*] didn't change. The block for B[*] is 
already correct in trunk and doesn't need changing.

Here is my ChangeLog:


2011-07-22  Daniel Carrera  <dcarrera@gmail.com>

	* trans.c (gfc__allocate_allocatable): [PR 4755] Do not fix
	and the reallocate a variable that is already allocated.


diff -r c8b6eb02738a gcc/fortran/trans.c
--- a/gcc/fortran/trans.c	Fri Jul 22 09:21:49 2011 +0000
+++ b/gcc/fortran/trans.c	Fri Jul 22 20:36:23 2011 +0200
@@ -775,13 +775,8 @@ gfc_allocate_allocatable (stmtblock_t * 
       stmtblock_t set_status_block;
 
       gfc_start_block (&set_status_block);
-      tmp = build_call_expr_loc (input_location,
-			     built_in_decls[BUILT_IN_FREE], 1,
-			     fold_convert (pvoid_type_node, mem));
-      gfc_add_expr_to_block (&set_status_block, tmp);
 
-      tmp = gfc_allocate_using_malloc (&set_status_block, size, status);
-      gfc_add_modify (&set_status_block, res, fold_convert (type, tmp));
+      gfc_add_modify (&set_status_block, res, fold_convert (type, mem));
 
       gfc_add_modify (&set_status_block, status,
 		      build_int_cst (status_type, LIBERROR_ALLOCATION));