re PR fortran/35810 ([TR 15581 / F2003] Automatic reallocation on assignment to allocatable variables)

2010-11-28  Paul Thomas  <pault@gcc.gnu.org>

	 PR fortran/35810
	* trans-array.c (gfc_trans_array_constructor): If the loop->to
	is a VAR_DECL, assume this is dynamic. In this case, use the
	counter to obtain the value and set loop->to appropriately.
	(gfc_conv_ss_descriptor): Always save the offset of a variable
	in info.saved_offset.
	(gfc_conv_ss_startstride): Do not attempt bound checking of the
	lhs of an assignment, if allocatable and f2003 is allowed.
	(gfc_conv_loop_setup): If possible, do not use an allocatable
	lhs variable for the loopspec.
	(gfc_is_reallocatable_lhs): New function.
	(get_std_lbound): New function.
	(gfc_alloc_allocatable_for_assignment): New function.
	* gfortran.h : Add flag_realloc_lhs to the options structure.
	* lang.opt : Add option f(no-)realloc-lhs.
	* invoke.texi : Document option f(no-)realloc-lhs.
	* options.c (gfc_init_options, gfc_post_options,
	gfc_handle_option): Incorporate f(no-)realloc-lhs with default
	to frealloc_lhs for -std > f95.
	* trans-array.h : Add primitive for previous.
	* trans-expr.c (gfc_conv_string_length): Return if character
	length is a variable and the expression is NULL.
	(gfc_conv_procedure_call): If the call is of the kind x = f(...)
	and the lhs is allocatable and reallocation on assignment OK,
	call gfc_alloc_allocatable_for_assignment. Do not generate the
	function call unless direct by reference.
	(realloc_lhs_loop_for_fcn_call): New function.
	(realloc_lhs_bounds_for_intrinsic_call): New function.
	(gfc_trans_arrayfunc_assign): Reallocation assignments need
	a loopinfo and for the loop bounds to be set.  With intrinsic
	functions, free the lhs data and let the library allocate the
	data array. Done by the new functions above.
	(gfc_trans_assignment_1): If the lhs is allocatable and
	reallocation on assignment is allowed, mark the lhs and use
	gfc_alloc_allocatable_for_assignment to make the reallocation.
	* trans.h : Add is_alloc_lhs bitfield to gfc_ss structure.

2010-11-28  Paul Thomas  <pault@gcc.gnu.org

	PR fortran/35810
	* gfortran.dg/realloc_on_assign_1.f03: New test.
	* gfortran.dg/realloc_on_assign_2.f03: New test.
	* gfortran.dg/transpose_2.f90: dg-option -fno-realloc-lhs.
	* gfortran.dg/unpack_bounds_1.f90: The same.
	* gfortran.dg/cshift_bounds_2.f90: The same.
	* gfortran.dg/matmul_bounds_2.f90: The same.
	* gfortran.dg/matmul_bounds_3.f90: The same.
	* gfortran.dg/matmul_bounds_4.f90: The same.
	* gfortran.dg/matmul_bounds_5.f90: The same.

From-SVN: r167220

1 files changed, 15 insertions, 0 deletions

diff --git a/gcc/fortran/options.c b/gcc/fortran/options.c
index 5381fde..1f1cdd1 100644
--- a/gcc/fortran/options.c
+++ b/gcc/fortran/options.c
@@ -149,6 +149,7 @@ gfc_init_options (unsigned int decoded_options_count,
   gfc_option.flag_init_character_value = (char)0;
   gfc_option.flag_align_commons = 1;
   gfc_option.flag_protect_parens = 1;
+  gfc_option.flag_realloc_lhs = -1;
   
   gfc_option.fpe = 0;
   gfc_option.rtcheck = 0;
@@ -266,6 +267,16 @@ gfc_post_options (const char **pfilename)
   if (flag_associative_math == -1)
     flag_associative_math = (!flag_trapping_math && !flag_signed_zeros);
 
+  /* By default, disable (re)allocation during assignment for -std=f95,
+     and enable it for F2003/F2008/GNU/Legacy. */
+  if (gfc_option.flag_realloc_lhs == -1)
+    {
+      if (gfc_option.allow_std & GFC_STD_F2003)
+	gfc_option.flag_realloc_lhs = 1;
+      else
+	gfc_option.flag_realloc_lhs = 0;
+    }
+
   /* -fbounds-check is equivalent to -fcheck=bounds */
   if (flag_bounds_check)
     gfc_option.rtcheck |= GFC_RTCHECK_BOUNDS;
@@ -964,6 +975,10 @@ gfc_handle_option (size_t scode, const char *arg, int value,
       gfc_option.flag_protect_parens = value;
       break;
 
+    case OPT_frealloc_lhs:
+      gfc_option.flag_realloc_lhs = value;
+      break;
+
     case OPT_fcheck_:
       gfc_handle_runtime_check_option (arg);
       break;