[Patch, Fotran] Fix PR 4755 - Do not free + reallocate a variable that is already allocated.

[Daniel Carrera <dcarrera at gmail dot com>]

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.
--
I'm not overweight, I'm undertall.

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));

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